DE1772022A1 - Device for reproducing an image - Google Patents

Description

5796-68 / Sch / Ro. μι on "·

P 19580 West-Germany I ' t & V4.

US Ser. No. 625.0 ^ 8
Filed: March 22, 1967

Printing Developments, Inc. Time & Life Building, Rockefeller Center New York, N.Y., (V.St.A.)

Device for reproducing an image .

The invention relates to a device for reproducing an ' image, in which an original is scanned point by point according to a first scanning pattern and at the same time a recording medium is scanned point by point while recording the information obtained during the scanning of the original in accordance with a second scanning pattern, recording elements on the recording medium are formed, which correspond to each information-wise assigned scanned parts of the original and the information-wise corresponding parts of the original and the recording are normally assigned to one another in terms of position such that the centers of their surface areas are located at corresponding points of the two scanning patterns.

When reproducing images with intermediate tones, e.g. photographs, Drawings and the like. By printing, the original having continuous tonal values must, for example, be converted into a screened Halftone image can be converted on one or more printing plates, depending on whether it is color or multi-color printing acts. With such printing plates the image is known to be reproduced by a number of ink dots, which have small dimensions in relatively bright image areas and large dimensions in relatively dark image areas.

Heretofore, the original having continuous tone values has usually been converted into the desired one by a photographic process Halftone converted. Here is a grid plate

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placed between the original and a photosensitive film and the original is projected through the screen plate onto the film, which after development has screened the desired one Halftone supplies. A disadvantage of this photographic process is that the boundaries between areas of different tone density in the halftone image become relatively irregular and look "frayed". In addition, if at least part of the conversion the continuous tone values on the iron original works in a halftone image with electronic image reproduction, represents the need to switch from electronic to photographic processes for producing a halftone image a factor which increases the costs and the inconvenience of the process not insignificantly.

It is true that photo-engraving machines are already known, with the aid of which they can transform an original with continuous tonal values a halftone printing plate can be produced that halftone dots from a metal plate by means of an engraving tool be cut out.

There are also electronic devices are known for generating a halftone image on a photographic film (US Patent 1685 93 * and 2,818,461). Even with these known devices, however, tone density boundaries in the halftone image are relatively irregular.

The invention is accordingly based on the object of avoiding this disadvantage and an electronic device to specify for the reproduction of an image, in which a change in the size and / or shape and / or position of the points of the image accordingly a sampling of a tone density gradient in the original is possible.

This object is achieved in a device of the type mentioned according to the invention by an arrangement which the scanning of the recording medium when there is a change in the the scanning of the original changes in such a way that the surface centers of the recording elements the normal position in which the assignment to the surface centers of the information-wise corresponding parts of the original exists,

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be moved.

In one embodiment of the invention, in the scanning of the original having continuous tone values an image signal is generated and a signal is generated at the same time, which is suitable for dividing the image signal into dot intervals. A resulting signal for actuating a recording arrangement which scans the recording medium is generated from these two signals. The recording arrangement is through the resulting signal controlled so that on the record carrier Points are recorded that form a halftone image of the continuous Original with tonal values on the recording

m carrier form. ■. m

In accordance with a feature of the invention, an arrangement is provided for changing the size or shape of the recorded dots. According to another feature of the invention, as already mentioned, precautions are taken around the center points of the surface areas to shift the points formed on the recording medium with respect to their normal positions.

The invention is based on typical exemplary embodiments explained in more detail in connection with the drawing, it shows:

Fig. La to Ic halftone dot patterns as they are used for printing Image areas of different tone values can be used;

2 shows a schematic representation of an embodiment game according to the invention;

FIG. 1 is a schematic representation of a knitting grid scanning device, which forms part of the device shown in Figure 2;

FIGS. 4 and 5 show enlarged details of the scanning device shown in FIG. J;

FIG. 6 is a schematic representation of an original image scanning device which forms part of the device shown in FIG forms;

FIG. 7 shows an enlarged illustration of part of the scanning device shown in FIG. 6;

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FIG. 8 is a block diagram of an electronic circuit which can be used in the device according to FIG. 2;

Flg. FIG. 9 is a graphic illustration for explaining the mode of operation of the circuit arrangement shown in FIG. 8; FIG.

Fig. 10 is a simplified sectional view of recording apparatus which forms part of the apparatus shown in Fig. 2;

Figures 11, 12a and 12b are enlarged schematic views of portions of the recording apparatus shown in Figure 10;

Fig. 13 is an enlarged view of part of the recording medium for the recording apparatus shown in Figs. 2 and 10;

14a, 14b, 15a, 15b, 16a and 16b are graphic representations for explaining the mode of operation of the one shown in FIG Means for generating halftone dots when the original has no tone density jump;

17 shows a representation of a tone density jump when reproduced by a known halftone printing or autotype process;

18 to 21 are graphical representations of various types of tone density jumps which may occur when an original image is scanned;

22a to 22c representations of opposite FAg. 18 modified tone density jumps;

FIG. 23 is a circuit diagram of a deflection circuit shown in FIG is shown only in block form;

Flg. 24 to 26 diagrams to explain the operation the deflection circuit shown in Fig. 23;

Fig. 27 to 30 representations to explain the work * wise the device shown in Fig. 2 upon occurrence a jump in tone density, as shown in Flg. 18 is shown; i

31 to 34 are illustrations for explaining the operation the device shown in Fig. 2 upon occurrence of the tone density jump shown in f Fig. 19; j

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Pig 35 is a visual image of a vibration shaping stage shown in Pig · 8 is only shown in block form «and

Pig »36 a circuit diagram of one in Pig. 8 shown only in block form left control and comparison stage.

In the following description they are corresponding or have the same effect Parts are denoted by the same reference numerals, but to which an accent or indices have been added to distinguish them. Unless expressly mentioned, the description for a specific element also applies to its counterparts.

Generation of a halftone image by means of a halftone screen

Fig. La shows a white paper sheet 30 with an area ™ 31a, on which a white or very light even tone value is represented by a conventional halftone printing process. Of the Area 31 is through equally spaced apart horizontal and vertical lines 32a, 33a in square Halftone dot zones 34a divided, in each of the centers of which there is a small halftone dot 35a made of black printing ink. The point 35a is ideally round, but in practice it can be more or less diamond-shaped. The halftone or halftone dots, 35a have surface area points 37a, which are located at predetermined normal locations and in the intersections of a rust or Lattice-shaped pattern from a first group of parallel equidistant lines 38a and a second group of parallel equidistant lines | solid lines 39a perpendicular to those of the first group, are located.

If the raster points 35a are generated with the aid of a photographic raster, the lines 32a and 33a correspond to the Lines of the grid and the number of lines 32a, 33a per inch can be significantly below 100 for a coarse print and for one high quality printing can be significantly above 100, with 100 lines per inch being a typical value. The corresponding Small dots in a letterpress plate do the useful job of keeping the recessed areas not inked with ink to keep the printing plate at a distance from the paper 30.

Fig. Ib shows another area 31b of the paper 30, on which a medium gray tone is reproduced by black raster points 35b.

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is given, which are ideally diamond-shaped. The grid point are so large that their corners lie on the sides of the halftone dot zones 34e.

Fig. Ic shows again another Bereloh 3I0 of the paper ! 30, in which a black tone is represented by black raster points 35c is reproduced, which are so large that they are the associated; Fill in grid dot zones 34c up to the corners and therefore merge with the dots of the adjacent zones.

The grid points 35c are theoretically octagonal and leave

\ Diamond-shaped spaces 36c notify at the contact points 4! Barter zones 34c free. In practice the guessing points 38c give way however, from the octagonal shape and leave gaps 360 free, that are more or less round "

It can be seen that area 31c is the inverse of area 31a in tone density because of the white spaces 36c of the area 31c, with the exception of their location, is the black Corresponding to grid points 35a of the area 31a and the large black grid points 35c of the area 31c with the exception of the position correspond to the white spaces that the guessing points 35a in surround the zones 34a of the area 31a.

I General description of the facility

'Fig. 2 shows schematically a device for reproduction of an original image having continuous tonal values by means of raster points of the type shown in FIGS Fig. 2 shown device includes a base plate 40 on which a motor 41 and bearings 42, 43 are arranged, the one by the motor driven shaft 44 mount. Between the bearings 42, an opaque drum 45 is mounted on the shaft 44, dj, e revolves with the wave. With the one to the left of camp 43 left end of the shaft 44 is the right end of a transparent, hollow drum 46 fixed coaxially, which is open at the left end and is rotated by the shaft 44. The drum 46 has the same outer diameter as the drum 45

Around the left end of the drum 46 there is wrapped a strip 50 of developed photographic film which has a striohgitter-

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like pattern of white stripes 52 alternating with black stripes 51 (see also FIG. 4). Upon rotation of the drum 46 through the shaft 44 of the film strip 50 is a ^sample-1 zone 55 moves "which is as large in the circumferential direction of the drum in that it comprises a plurality of black stripes 51st In the ! the left end of the drum 46 is a light projector of the type; Periscope, which is shown schematically as light source 54 and lens ¹ 55 and in the scanning zone 53 allows a light beam to fall through the film strip 50, which allows an image of the part of the film strip located in the scanning zone 55 to fall on a scanning device 56 which is located on the Base plate 40 is arranged. As will be explained in more detail, the M scanning device 56 generates a periodic signal from the light image, which signal is available on an output line 57.

A representation of an original image 60, which is to be reproduced as a halftone image on a recording medium 61 which is on the drum, is also arranged on the drum 46 is arranged. In the device shown in Fig. 2, the original image consists of a photographic black and white trans parent image, from which it is assumed for the sake of simplicity that it is a positive, and the recording medium 61 consists of a piece of photographic film.

With the synchronous rotation of the drums 45-46 by the Wave 44 becomes the original image 60 and the recording medium | 60 are scanned synchronously by an image scanner 62 or an image recording device 63, both of which are on a support 64 are mounted, which iet slidably mounted parallel to the axis of the drums on guide tracks 65 "which are arranged on the base plate 40. The support 64 rests while the devices 6a, 63 scan the original image 60 or the recording medium 61. Between the individual scans, however, the support is provided by a linear feed device 66, which is known in FIG Welse (US Pat. No. 2,778,232) can be designed to shift the width of a scanning track one step to the left.

The devices 62, 63 correspondingly scan the sheets 60, 61 containing the original image or forming the recording medium in identical raster patterns, which consist of adjacent

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mutually extending scan lines or tracks exist. the The number of scanning tracks per unit of length across the scanning direction is the same as the number of black stripes in both scanning patterns 51 per unit length on the filmstrip 50 in the direction of the Circumference of the drum 46. The distances between the black stripes in the film strip 50 is therefore equal to the width of the scanning tracks in the scanning patterns; this width can be, for example, 0.25 mm (10/1000 inches).

The image scanner 62 is operated as follows: In the open left end of the drum 46 is a periskopartiger spotlights 70 schematically by a light source 71 and a lens 72 is shown inserted and mechanically coupled to the support 64 W indicated by a broken line 73 is indicated so that it moves axially with the image scanner 62. The light projector 70 throws a light beam through the transparent, positive original LiId 60, so that in the scanning device 62 a light image of the sound | value details of the original falls within a limited illuminated area. Through this area, the original image is scanned as the drum 46 rotates.

The image scanner 62 generates an area signal from the incident light image which occurs on an output line 74 and represents the integral of the tonal values of the positive original image within the entire illuminated area.

The image scanner 62 also detects the tonal values in W in the middle of the mentioned area within an illuminated strip-like or slit-shaped spot, the width of which, perpendicular to the scanning direction, is equal to the advance of the image scanner during one step of the axial displacement effected by the advance device 66. As a result of the rotation of the drum 46, during each scan of the raster pattern through which the original is scanned as a whole, the spot scans a straight scanning track the width of which is equal to that of the spot.

Provides the light from the aforementioned elongated slit spot an image signal from which the image scanner 62 generates left and right electrical field signals which are on output lines 81 and 81 'occur and the tonal values of the original represent within the area of the elongated slit spot,

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'to the left and right of the center line of the spot ; described scanning track are located.

; The periodic signal on line 57, the area signal on line Ik and the left and right field signals on lines 81 and 81 'are fed to an electronic raster dot generator unit 90, the more detailed description of which follows j. Within this unit, the field signals 'are changed ■ the range signal, combined with the periodic signal' by defined and otherwise processed so that j at the output of unit 90 a Gesamthalbtonpunktsignal occurs, in a left Komj (Linksablenksignal) component on a line 91 and a right component (right deflection signal) on a line 91 'is divided ^. The two deflection signals are left and right respectively; Input of the recording device 6j3 supplied to the control thereof.

The recording device 63 throws at the out of one Photosensitive film existing recording medium 61 a light beam, which on the film a bright, strip-shaped or slit-shaped Forms spot (exposure spot), the wider side of which: runs perpendicular to the direction in which the film passes through the device is scanned. In its latitude, the stain is

■ tion is divided into a left and a right area, the

■ lie on opposite sides of a point that serves as the reference center of the spot. The width of these sub-areas of the Ä

: Flecks is controlled by a double light lock 100 that in turn controlled by the deflection signals on lines 91, 91 ' will.

The exposure spot sweeps as the drum 45 rotates over the film 61 and writes on the film (while scanning the raster pattern through which the entire recording surface of the film is scanned) a scanning track, the width of which corresponds to the nominal width of the exposure spot, if both the left and right portions of a patch are full width and have a reference center line on which the mentioned reference center point of the b'leck moves, if the spot moves across the film. The width of the spot is modulated during the scan so that within the mentioned

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Scanning track successive halftone dots exposed on the film will. Normally, these halftone dots are arranged so that they are symmetrical about the center line of the scan track are divided, but in certain cases a jump in tone density in the original image 60 has the consequence that the center of the area of the Exposure spot is deflected from the center line to the left or right, around the limit of the jump in tone To give image areas in the reproduction on the recording medium 61 a smoother appearance. By recording the described raster points in all scanning tracks of the raster pattern, according to which the recording medium 6l is scanned, generated the image recording device 63 forms a complete halftone image of the positive on the film forming the recording medium 6l Originals 60. For the sake of simplicity, assume that this halftone image is positive with respect to the Original image acts, so that white, gray and black areas of the original in the halftone image are represented by similar halftone dot patterns as shown in Figs. La, Ib and Ic are.

In the following, the details of those shown in FIG. 2 will now be discussed Establishment to be received.

Stripe and image scanners

In the case of the scanning device 56 shown in more detail in FIG. 3 for the film strip 50, the light incident on the film 50 through the lattice-like pattern is through a lens 110 into the Focused plane of a diaphragm 111, so that an image of the part located in the scanning zone 53 (FIG. 2) in the diaphragm plane of the film strip 50 is created. The diaphragm 111 has a light passage opening 112, the shape of which is shown by the dashed outline II3 in FIG. The opening 112 is limited the scanning zone 53 traversed by the filmstrip 50 and from the scanning device 56 is detected. The dashed line II3 thus also indicates the shape of the scanning zone 53.

4 can thus be seen as a direct view of part of the filmstrip 50 together with the scanning zone 53 or as a representation of the image of this part of the strip in the plane of the diaphragm 111

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samraen with the outline lljj of the aperture 112 can be viewed. Depending on the magnification of the optics contained in the scanner 56, the portion of the filmstrip within the zone the same size (the magnification is then 1: 1) or a different size than the part of the image delimited by the opening 112 of the film strip. The two views for which FIG. 4 can be viewed as a representation can therefore be the same or different standards apply. To simplify the following description, it should be assumed with respect to FIG. 4 that firstly, FIG. 4 shows a view of the delimitation of the diaphragm opening 112 and the image of the filmstrip projected into the plane of the diaphragm 111 50 and that secondly for FIG. 4 the same scale applies as for Fig. 5.

Immediately behind the opening 112 on the aperture 111 is a Mask II5 arranged to be seen from one piece of a pnotographis Film can exist. The mask II5 forms a pattern of dark ones Stripes II6, the light transmittance of which is low, and light stripes 117 »which have a high light transmittance and alternate with the dark stripes. The strips 116, 117 of the mask II5 are in the scanning direction running perpendicularly in FIGS of the film strip 50 equally thick by ": they also have in this direction the same thickness as that shown in FIG Images of the black and white stripes of the scanned filmstrip 50. So when the filmstrip 50 passes through the Scanning zone 5J5 moved, occur between the individual strip images according to FIG. 4 and the strips of the mask II5 successively spatial Phase shifts from.: Όϋ ° to. At one point during of this shift, the images of the black stripes according to FIG. 4 fully coincide with the transparent stripes of the mask 115, so that only a minimum of light can then pass through the opening 112 and the mask 115, while in the case of a phase-wise the images of the dark stripes are exactly offset by 180 ° with the dark stripes of the mask Gecken, so that a maximum of light then passes through the opening 112 and the mask 115 can. From this it follows that the intensity of the Aperture opening and the light passing through the mask during successive periods in each case between a minimum value and a maximum value changes, where each Perlode represents the period of time

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corresponds to the need for a black or white stripe of the film strip 50 in order to fully enter the scanning zone 53 or to leave it entirely. The light modulated in its intensity! is represented by optics, shown in simplified form as lens II8; thrown a phototransistor 120 , which converts the intensity fluctuations of the light into corresponding amplitude fluctuations of an electrical signal. The periodically variable electrical signal is available on the output line 57. j

In a conventional marker scanning device, the j individual strips of film 50 would be scanned individually and the perio-; that of the generated signal would be the respectively scanned strip! correspond. The scanning device 56 differs from such a conventional scanning device in that the cyclic signal is obtained with the aid of the mask II5 by simultaneously scanning a plurality of dark and light strips of the film 50 . That ; simultaneously scanning a plurality of strips of the film ^has: the advantage that local irregularities are averaged out in the width or position of the strips and the periodic signal is therefore not affected by such irregularities. '

. In the in Figure 6 in more detail image scanning apparatus 62 illustrated the CLIENT that the original has passed through 60, to means ι an optical system represented by a lens 125 into an image of a j-limited illuminated area of the ^original; the reflective face of a bezel 126 focuses. From this entire image , light is reflected by the diaphragm and thrown by means of an optical system represented by a lens 127 onto a phototransistor 123, which converts the incident light into the range signal available on line 74.

The diaphragm 126 has a slit-like, rectangular opening 129, the light of the projected image emitted by an illuminated rectangular spot 1 ^ 0 (Fig. 7) * which has the same shape as the rectangular opening 129, and in the original 60 in the center of the whole illuminated area of the original lies, originates, lets through. Depending on the imaging scale of the optics of the image scanning device 62, the size of the spot I) O may or may not correspond to the size of the aperture opening 129.

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The outline of the rectangular spot I30 is dashed in FIG shown. The width of this spot across the scan direction

, is equal to a feeding step of the by the feeding device 66 driven carriage 64. This step width is

I for their part again according to the fineness of the desired halftone screen, recorded on the film 6l.

; When the fineness of the halftone image is 100 lines per inch the grid line spacing in the picture is 10/1000 inches: and the displacement of the carriage 64 per step as well as the width

j te of spot I30 are both also 10/1000 inches. In accordance with the teachings of United States Patent 3 ± 94 883 is the spot width at least twenty times, even preferably an essential μ lent greater factor smaller than that of side measured to side dimension of the illuminated area of the original, which the! Rectangular spot I30 surrounds and is detected by the phototransistor 128.

The spot 13Ο has a thickness perpendicular to the width direction or opening size that is much smaller than the width of the Stain. For example, with a width of 10/1000 inches, the opening width or thickness of the spot can be about 2/1000 inches.

As the drum 46 rotates, the spot I30 in the original 60 scans a scanning track 135, the width of which corresponds to that of the spot and the edges of which are shown in FIG. 7 by dot-dash lines 136 _e. In FIG. 7, it was assumed that A is the spot moved downward with respect to the original 60. The scan track I35 is divided by a center line 137 into a left and a right strip I38, I38 ¹ ; the center line divides the spot I30 into left and right halves 139 and 139 ', respectively.

While the spot I30 describes the track 135, this divided by the periodic signal from the reticle scanner 56; the periods of the signal correspond to intervals 132 dividing the scan track as shown by dash-dotted lines I33. In the case of the one shown in FIG Device, the length of the individual intervals is equal to the width of the scanning track I35, e.g. 10/1000 inches. The cyclical The signal from the scanning device 56 is therefore used in practice

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to divide the scan track 135 into square halftone dot zones 134 which lie between the lines I36 and are separated from one another by the lines 133.

The linear speed of the filmstrip 50 with respect to the scanner 36 is necessarily synchronized with and equal to the linear speed of the original 6O with respect to the Scanning device 62 because the filmstrip> 50 and the original 6O with the same angular velocity un. Run en and are arranged at the same radial distance from the axis of rotation. Since with the individual line scanning cycles have the same constant relationship between the instantaneous spatial phase of the stripe pattern on the filmstrip 50 with respect to the scanner 56 and the momentary space phase of the original 60 with respect to the scanning device 62 exists, form the square halftone dot zones 134 in scan tracks I35 horizontal rows from track to track as well as vertical rows in the individual tracks. The periodic signal from the scanning device 56 thus produces the pattern through which the original 60 is scanned into an array of aligned horizontal rows and aligned vertical columns contiguous square halftone dot zones 134 divided up.

The light from the spot I30 (Fig. 7) on the original 60, which passes through the rectangular opening 129 (Fig. 6), falls on a beam splitter 140 in the form of a metal wedge, which has a left and a right reflective side l4l and I4l ' having. The light from the left half 139 of the spot I30 is thrown from the side l4l of the beam splitter as a beam 142 through an optical system shown as a lens 14-3 onto a phototransistor 144. In a corresponding manner, the light is reflected from the right half I39 'of the spot I30 through the side 14l' of the beam splitter as beam 142 'and ^{thrown through a lens 143 1} onto a phototransistor 144'. The phototransistors 144, 144 'generate the left and right field signals from the light falling on them, which are available on the output lines 81 and 81'.

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Electronic switch

As mentioned, the raster signal from the photocell of the line grid scanner 56, the area signal, the left and right field signals from the phototransistors 128 and 144 * of the image scanner 62 are all fed to the electronic halftone dot generator unit 90 (Fig. 2), which is shown in Pig. shown in more detail as a block diagram. The unit 90 includes a raster signal channel 148, an area signal channel 149, and right and left field signal channels 150 and 150 ^1, respectively. All of these channels are constructed with semiconductor components or integrated circuits. The two field signal channels agree * with a few exceptions to be mentioned, so that only the left field signal channel 150 will be described in more detail.

The field signal of a presser stage is in the left channel I50 155, which the dynamic range of the signal in a desired, manually adjustable degrees, around the tone density range reproduced by the input signal on that To compress the clay density area so the film 6l can handle. It ... is known such To use dynamic presser stages in facsimile reproducers.

In the range signal channel 149, the signal generated by the phototransistor 128 is fed to an eater stage 156 corresponding to stage 155. After dynamic compression, the range signal ™ is fed to an inverter stage 154 and then combined separately with the left and right field ^{signals in adapter stages 157, 157 *, which follow presser stages 155 and 155 1 in the left and right channels 150 and 15C, respectively} . The adding stages 157, 157 * can each consist of a simple mixer circuit in which the two input signals are fed to a common connection point serving as an output terminal via a resistor each. The addition of the range signal to the image or field signal is known to increase the local contrast in the reproduction produced by means of the changed signal (USA patent J> 194 883). More specifically, the change in the image signal is caused by the area signal upon occurrence

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a local tonal value detail in the original, which differs in tonal value from the surrounding area, for enlargement the local contrast between such a detail and the surrounding area in the reproduction.

! From the adder 157 the left field signal is supplied to range and level control circuits I58, through which the DC voltage level of the signal and the maximum and minimum brightness (light and shadow) corresponding signal voltage values can be set manually. Then the signal a main deflection path I60 and an emitter amplifier I6I fed to both a left decentration deflection signal generator 162 and a steepening circuit I63, which will be discussed further below ™ will be discussed in more detail. The main diverter I60 simply consists of a line 164 through which the left field signal fed to the input of a left deflection control comparator I65 will.

In the raster signal channel 148 that shown above the line 57, which has approximately the shape of a triangular wave Periodic signal from the photocell 120 of the line grating scanner 56 is fed to a vibration shaper stage 170.

In the oscillation shaper stage 150 shown in more detail in FIG. 55, the signal from the photocell is transmitted via line 57 first a linear transistor amplifier 400 and then a limiting transistor amplifier 401, which operates on the tips "and valleys of the input signal does not respond. The The output circuit of the amplifier 401 contains a parallel resonance circuit 402 with a capacitance 403 and an inductance 404. The resonance circuit 402 is tuned to the orund frequency of the signal periodic at the input of the stage 170, so that a signal appears at the output of the amplifier 401 which has the same period as the original input signal but has the form of a sinusoidal oscillation. The filtering dee photocell signals j by a resonant circuit has the advantage that transient through the "flywheel ■ wheel effect" of the resonant circuit irregularities [be suppressed that the photocell output caused by dirt, small defects or streaks in the scanned stripe pattern on the filmstrip 50, or by the elektrooptisohe System through which>_;

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the stripe pattern is scanned, can arise.

The sinusoidal output of the amplifier 401 is two series-connected limiting transistor stages 405, supplied 4o6 the only resistances (so no capacitors) _f included, so that it is no DC bias occurring in these stages, in which the risk of drift or variation phenomena exists. The sinusoidal oscillation is severely cut off by the steps 405 # 406 and converted into a rectangular oscillation, the zero crossings of which correspond to those of the sinusoidal oscillation, while on the other hand it is independent of amplitude fluctuations or other changes in the waveform of the sinusoidal signal. This square wave is available on an output line 171 of the stage 170 and it has very steep straight leading and trailing edges, as the waveform shown above the line 171 in Fig. 8 shows . 8), which generates a periodic signal 190 in the form of a sawtooth or triangular oscillation from the square wave, the rising and falling edges of which are created by integrating the relatively positive and relatively negative parts of the square wave.

The periodic signal I90 is then fed to an amplitude and level setting circuit 173, by means of which the amplitude and the DC voltage level of the sawtooth oscillation can be set manually. The sawtooth raster signal set in amplitude and level is then fed via a line 174 to the left and right deflection control comparator stages I65 and 165 ¹ , which are also connected to the left or right field signal are fed.

The comparison stages also receive input signals from the amplification circuits I63 or 163 '. In the left The steepening circuit 16) passes through the left field signal j a first differentiating stage 180 in which it differentiates electrically is, and the resulting signal corresponding to the first differential quotient is then replaced by a signal (not shown) Inverteretufβ, which is the output part of the differentiating stage I80 can form, inverted. The inverted signal is then converted into a

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The second differentiating stage I8l is differentiated again and the resulting inverted, twice differentiated signal is fed via a line 182 to the comparison stage I65, in which it is added to the left field signal before the latter is compared in a manner to be described with the tooth raster signal fed to the comparison stage . As is known, the change serves j of the field signal (or an image signal) by the inverted twice differentiated signal for the steepening of the ^Bildsig-: Nals in order to emphasize in the reproduction Tondichteränder sampled in the original.

j Fig. 36 shows details of the comparison stage I65. The above ! I left field signal applied to line 164 passes through first! a voltage attenuator potentiometer 420 which can be set as desired and is then connected to a connection point 21 with the via the

Line 182 fed steepening signal combined. The field signal changed in this way is then fed to the base of a PNP transistor 422 connected as an emitter amplifier,! whose Eraitter-collector path is in series with the collector-emitter path of an NPN transistor 423, which works as a limiter: zer with a variable level. The base of the transistor \ 423 is supplied to the Sägezahnrastersignal via line 174th The collector of the transistor 423 is connected via a resistor 424 to which a Zener diode 425 is connected in parallel to the positive terminal of a voltage source to which, for example, a; regulated voltage of 12 volts.

The limiter transistor 423 is controlled by the field signal via transistor 422 so that in the collector ! Emitter path of the transistor 423 as long as no significant current flows than the instantaneous amplitude of the sawtooth signal 19O iaon the line 174 greater than the level of the field signal 1st. ! However, if this condition is met, transistor j 423 produces a left halftone dot signal in at output resistor 424 ! Form a voltage proportional to the difference between the j instantaneous amplitude of the sawtooth signal and the simul-ιtlg The prevailing level of the field signal is, as long as this voltage does not exceed the threshold value of the Zener diode, at j which this diode 425 begins to conduct appreciably. When the span- j

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The halftone dot signal tends to exceed the threshold of the Exceeding Zenerdlode 425 directs this and limits the • voltage rise to a value close to the threshold value, ! so that practically the peaks of the halftone dot signal are cut off.

For a more detailed explanation of the operation of the comparison! At stage I65, reference is made to FIG. In FIG. 9, the illustrated period t of the sawtooth signal 190 corresponds to the width of a strip of film 50 calculated in the scanning direction (FIG. 4) and the length calculated in the scanning direction of one of the 1 intervals 132 (FIG. 7) in which the scanning track 135 in in practice, is subdivided by the raster signal 190 (Fig. 9). %

Assume first that the amplitude of the left field signal is the white level represented by the upper line 19I is equivalent to. The instantaneous amplitude of the signal exceeds I90 then the signal level corresponding to the white value 19I only during a short time interval in the middle of the period t and only during this small interval the comparison stage supplies an output signal. Since the instantaneous amplitude of this output signal is proportional to the difference between the instantaneous : is the amplitude of the signal I90 and the white value I9I, that is Output signal from a brief triangular pulse, , the shape of which corresponds to the small triangular part of the signal 190, which is located above the level I9I. Ä

Next, assume that the amplitude of the left field signal corresponds to an average gray level represented by the dashed line 192. In this case the Difference between the sawtooth signal 190 and the Qraupegel des Field signal only at the beginning and at the end of the period t equal to zero, while the amplitude of the signal I90 in the rest of the time exceeds the level I92. The output signal of the comparison stage I is then accordingly a triangular oscillation, which in size and Shape is proportional to the whole triangle of signal 19O, which is above level 192 and in the horizontal direction extends over the entire period t.

009832/0775

Finally, let it be assumed that the amplitude dee left field signal corresponds to the black level shown by the dashed line 193. The momentary amplitude dee Signal 190 is then also at the beginning and at the end of period t

ι greater than the level of the field signals. The output signal of the Comparison stage is then a halftone dot signal in the form of a

, intersected triangular vibration component which is superimposed on a DC voltage component. If the Zenerdlode 425 doesn't were present, the triangular component of this oscillation would correspond in amplitude and shape to the triangular part of the signals I90, which in FIG. 9 is above the level I92. Through the However, Zener diode 425 will cut off the tip of the triangular shaped signal component. The amplitude of the DC component of the semitone signal is the difference between the levels 192 and 193 proportional.

It is evident that the size or the size and shape the left generated in the comparison process described Halftone dot signal are variable depending on the size of the field signal.

In the comparison stage 165, the limiter stage is followed by further customary stages which contain transistors 426 and 427 (FIG. 36) and are used to amplify the signal and to set the DC voltage level of this signal. After the DC voltage level has been amplified and adjusted, the halftone dot signal is fed via a line 194 to an adder 200 (FIG. 8) which fulfills an important function in the present device The output signal of the adder 200 is amplified by a power amplifier 201 and then fed via the line 91 to the light lock 100 in the image recording device 63 as one of the two electrical input signals is fed to a power amplifier 201 via a line 91 ^1. This right signal is generated in the right channel 150 * from the sawtooth output signal of channel 148 and the right field signal in the same way,

00 9 8 32/077 5

how the left halftone dot signal is generated from the sawtooth signal and the left field proper. The right halftone dot signal is inverted with respect to the left halftone dot signal by an inverter stage which is present in the right deflection control comparison stage 165 ¹ but is absent in the left comparison stage 165 before it is fed to the light lock 100 in the Polari-j tat.

Halftone dot recording

Fig. 10 is a sectional plan view showing details of the dual light lock 100 and its associated components; constituting the image recording device 63 are taken out can be. The light lock 100 contains two magnetizable Polstüoke 205 »206, the rear parts of each (one on the plane perpendicular to the plane of the drawing) have a cross section in the form of an elongated rectangle, the long sides of which stand perpendicular to the plane of the drawing. The front parts of the PoI pieces 205, 206 are wedge-shaped and taper to a flux gap 207 which separates the two pole pieces. In the gap 207 a strong permanent magnetic field by means of two horseshoe-shaped ones Permanent magnets 208, 208 * generated, which are only partially shown in Fig. 10. The north poles of these two magnets are on opposite sides of the rectangular rear part of the pole piece 206, while the south poles on opposite Sides of the rectangular rear part of the pole piece 205 abut.

The pole piece 205 is penetrated by a central bore 211, which extends from the rear end of the pole piece to the gap 207 and tapers conically in the front part in the direction of the gap 207. The pole piece 206 has a corresponding bore 212. The; Bores 211, 212 are coaxial and together form a light \ path which extends through the pole piece 206, the gap 207 and the pole piece 205th

A light source 215 is arranged behind the plate 206. The light emanating from the light source 215 is transformed into an optical system, which is shown schematically as a lens 216 Focused bundle 217 through the bore 212 along the

009832/0775

Aohse runs. The light bundle then penetrates the gap 207 and the bore 212 and the light beam emerging from this bore is through an optical system, which is sohematisoh as a lens

218 is focused in a spot 220 on the film 61 disposed on the rotating drum 45 (Fig. 2) j is.

As shown most clearly in Fig. 11 can be seen, at the front end of the pole piece 205 in the gap 7, two thin parallel ί plates 221, 222 mounted, which extends over the circular Off-, voltage '219 of the bore extending 211 and together with the opening

219 limit an aperture slot 223. Through this slot is the light beam passing through the bore 211 is limited in such a way that the spot 220 on the film 61 has the shape of a slit or rectangle corner has (see Fig. 13) which (if size ut ^ d shape of the spot

220 can be determined exclusively by the slot 223) is an image of the rectangular patch I30 (FIG. 7) in terms of shape and its width equal to the length of a feed step of the step-by-step axially displaced by the feed device 66 Carriage 64 (Fig. 2) is. If the light bundle 217 forming the spot 220 is limited exclusively by the aperture slit 223, the rectangular spot 220 in the above-mentioned dimensioning example has a direction perpendicular to the scanning direction. Average width of 10/1000 inches and a thickness calculated in the scan direction of 2/1000 inches. Depending on the optics used in the recording device 63, the full width of the slit

: shaped rectangular spot 220 have the same width as the aperture slit 223 or a different width.

The width of the rectangular patch 220 can be controlled by a left and a right current-carrying metal belt 225 and 225 ', respectively. These metal bands are arranged in the gap 207 in the path of the bundle of light 217 and run in the gap perpendicular to the axis : _{of the bores 211, 212 and to the plane in which the magnets 208, 208 ^r ! lie. The strips are each formed by a layer structure made up of a titanium strip about 12.5 μm thick, which is joined by epoxy resin with an aluminum strip of the same thickness! is bound, exists. The titanium strip and the aluminum strip; give the bands, independently of one another, the required i

009832/0775

mechanical strength and the required electrical conductivity: Ability to The two bands are each about 64 mn »long and clamped tightly between brackets (not shown). Of the The largest part of the length of the strips is located in the gap 207 between the pole pieces 205 * 206 and is therefore exposed to the magnetic field prevailing in the gap.

In contrast to the prior art, the light lock is large enough to allow the ribbons to be transversely deflected by up to 0 _# ) 8 mm (15/1000 inches) per ribbon. In contrast to this, the known light locks, such as those used, for example, for recording the sound track in sound film technology, are designed for a maximum deflection per band of only about 25 / µm (1/1000 of an inch).

As FIG. 10 shows, the bands 225, 225 'are slightly offset from one another in the direction of the ι light bundle 217 and they overlap somewhat transversely to the direction of the bundle, so that the bundle is completely blocked when both bands are de-energized. '·. The left band 225 is traversed by current corresponding to the left half-tone dot signal in the downward direction, so that the middle part 230 (FIG. 12a) of this band as a result of the opposing! term repulsion of the permanent magnetic field in the flux gap 207 and: the magnetic field j generated by the excitation current around the band 225 is deflected to the left. In the right band 225 *, the right ^: halftone dot signal generates an upwardly flowing excitation current through the band which causes the center portion 230 * of the right band to be deflected to the right.

Various deflection amplitudes of the bands are shown in FIGS. 11, 12a and 12b. In Fig. 11, neither of the bands becomes j traversed by the Signaletron so that their deflection is zero and the path of the light beam 217 to the film 61 is completely blocked will.

In Figure 12a, the bands 225, 225 'are through signal currents medium strength and equal values deflected so that the middle part of the bands delimit a band gap 240, which is in the The center measured in the width direction is denoted by a broken line 241. The deflections of both ligaments are from the center

009832/0775

- a * - - 1772023.

241 is directed away and the center 241 of the band gap coincides with the center of the slot 242 (FIG. 11) in the entire dynamic deflection range of the two bands.

With every belt deflection, the total deflection of each belt can be divided into a centric component, which is directed away from the other belt, and an acentric component, which is either directed away from the other belt j other band is directed away from or towards this and can either be smaller or larger than the central component »be dismantled. In this context, to the right or left directed distractions are assigned the positive or negative sign. The two centric deflection components of the Both bands have the same amounts but opposite signs and the acentric deflection components of the two bands have the same amounts and the same signs. If the entire individual deflection of each band is broken down in this way, the width of the band gap 240 is equal to twice the amount of the central component of the deflection of the two bands and the transverse displacement of the gap center 241 with respect to the slot center 242 has the same amount and the same sign as the acentric one Component of the deflection of each of the two ligaments. In other words, the amount of the centric deflection component of the two bands can be determined by halving the width of the band gap 240, while the amount and sign of any acentric component of the deflections of the two bands can be determined just as easily, since this component is in magnitude and Sign with a possible shift of the band gap center Al with respect to the slot center 242 t coincides.

At the In Flg. 12a, the amount of deflection is not sufficient to bring the inner edges of the central parts 2) 0, 230 ^{f of} the bands beyond the time limits of the opening 223. The width of the spot 220 then changes according to the width of the gap 240 between the two bands. In Fig. 12b the two \

Bands, on the other hand, are caused by strong signal currents over the ends of the! Slot opening 223 has been deflected out and the width of the j As long as this condition lasts, the Width of the slot 223 determined and accordingly has its _{

009832/0775

Maximum value of aB 10/1000 inches. This state is maintained until the amplitude of the signal currents flowing through the bands has dropped so far that the edges of the bands come back into the area between the ends of the slot 223 and control the width of the spot 220 again. The width of the spot is then again controlled by the bands until the latter are again deflected beyond the ends of the aperture slit. In the case of the ^M overdeflection ^{n of} the ribbons shown in FIG. 12b, the Zener diode 425 (FIG. 36) prevents the currents in the ribbons from increasing to such great values that the resulting ribbon deflection would lead to damage to the ribbons.

When the drum 45 rotates, describes the slot-shaped; Spot 220 on film 61 (FIG. 13) is a straight scan track 250, the opposite edges of which are represented by dash-dotted lines 251. The width of the track 250 corresponds to the width of the area 252 which is occupied by the slit spot 220 when the bands 225, 225 ^% are deflected beyond the ends of the aperture slit 223. As shown, the track 250 defined by the width of the area 252 is divided into a left strip 253 and a right strip 254 by a center line 255 corresponding to the center 242 of the aperture slit.

Since it was assumed that the original was reproduced in its original size by the means shown in FIG the width of scan track 250 on film 61 is equal to the width of scan track 135 on original 60 (Fig. 7) * e.g. 10/1000 inches. The periods of the sawtooth signal I90 (FIG. 9) are used in a corresponding manner for rasterization and Subdivision of the scanning track 250 into longitudinal intervals 255 #, the boundaries of which are indicated by dash-dotted lines 256. the The length of the intervals 255 corresponds to the width of the track 250. The track is thus created by the sawtooth-shaped raster signal 190 divided into a sequence of square halftone dot zones 257. * j

The speed at which the spot 220 scans the film 61 is the speed at which the spot 130 scans the j Original 60 scanned, synchronized. In addition, since the scanning of the original 60, as already explained, spatially with the

009832/0775

SAD ORIGINAL

sampling the strips of film 50 is phase-locked and since the spatial scanning of the film 6l with the scanning dee Originals as a result of the coupled rotation of the drums 45, 46 is phase locked, the successive tracks have; 250 of the raster pattern with which the film 61 is scanned, the same spatial phase with respect to dot zones 257 as the spatial phase of the dot zones in the adjacent tracks. the Dot zones 257 in the scanning raster for the film 61 thus form horizontal rows and vertical columns, like the square halftone dot zones 134 (Flg. 7) in the scanning grid for the original 6O,

Halftone dot reproduction of uniform tonal values

14a to 16a and 14b to 16b show areas of different tone values of the original and the corresponding halftone dots recorded on the film 61 when the areas of uniform tone values of the original 60 are scanned. It is assumed in FIGS. 14a to 16a that the slit-shaped spot 130 moves downward in a scanning track 135 and that a left and a right field signal are generated which correspond to the left and right strips I38 and I38 ^{1 of} the track, respectively . Since the scanned tonal values in FIGS. 14a to 16a are uniform, the levels of the two field signals for the respective tonal value are also of the same size and have a purely zen | tric deflections of the ligaments of the light lock. The different tone values shown in FIGS. 14a to 16a naturally result in field signals, the level of which is different for the different tone values.

In FIG. 14a, the scanned area of the original 60 is tinted white or very lightly. The erge- located during the scanning of the left strip 138 by the left half 139 of the scanning I30>, Bende light beam accordingly has a high intensity, and produces a left half image signal whose level corresponds to the white value I91 (Fig. 9). The described subtractive combination of the sawtooth signal I90 with an image signal whose level is dem '. Corresponds to white value, delivers a left half-tone dot signal with a triangular waveform, which corresponds to that part of the sawtooth signal 190 which exceeds the level 191 (FIG. 9). This lin-: '"ke ~ Ha" Ibtbnpünktsignal is in the form of a current of the light soleuse

009832/0775

100 and causes the left tape 225 to move from the slot-i center 242 by one proportional to the magnitude of the signal current! Amount is diverted. The time course of the deflection of the central part 230 of the belt 225 away from the slot center 242 So j corresponds to a brief triangular oscillation such as occurs in the left semitone signal that excites the tape.

The result of the described deflection of the left band of the light lock is shown in FIG. 14b. In the short-lasting distraction of the tape 225 between this band and the (Schlitzraitte 242 is released, an opening through which the light rays arrive 217 from the film 61 and there in each case a triangular left half of the different consecutive% dots is able to record 259 260. The symmetrical thereto Right halves 259 'of the raster dots .260 are recorded on the film 61 by actuation of the right band 225 ¹ by means of the right halftone dot signal which is generated during the scanning of the tonal value in the right strip 138 ^{1 of} the track 135. The right signal j is correct to A white or very light tone value of the original is thus reproduced on the (developed) film 6l by a pattern of small checkered black halftone dots 26O in a white field 258. Since the film 6l has a has a steep gradation, practically the entire area of the screen dots 260 is completely blackened.

j In FIG. 15a, the scanned tone value of the original 60 i is a medium gray. As explained in connection with FIG. 9, when such a gray tone is scanned, a left half-tone dot signal in the form of triangular oscillations is produced in the left strip 138 of the track 135, the duration of which corresponds to a full period t of the sawtooth oscillation 190 and is equal to that above the gray level 192 lying part of the sawtooth signal. When such a gray tone is scanned in the right strip I38 ¹ , a right half-tone dot signal is also generated which, with the exception that the polarity is opposite, corresponds to the left signal.

The two halftone dot signals, which have the shape of a triangular wave, cause a deflection of the left and right one Band 225, 225 * with a triangular time course, where

009832/0775

the bands are slightly outside the ends of the aperture slot 223 at maximum deflection. With such a deflection of the beam tapes each in a 217 records the left and right halves 261 and 261 ¹ of a series of black dots 263 duroh on the film 61,

'of the zones 257 into which the scanning track 250 is divided.

As shown in Fig. 15b, the left and right halves of the dots recorded by the exposure have as a first approximation the shape of triangles. Since the bands 225, 225 'at their

! maximum deflection, however, just outside the ends of the slots 223 are located at the edges 251 of the scanning track 250 The corners of the triangles forming the halves of the raster dots are truncated. The grid points 263 thus have the shape of unrege1 moderate hexagons, which, however, are almost square shaped. The grid points 263 touch all four rarities of the associated zone 257 and they form a checkerboard-like pattern with the white ones Gaps 264 that are between and approximately the same size as the grid points.

In Fig. 16a a black or very dark tone of the Originals 6O scanned. The field signal level for one dark tone value corresponds to black level 193 (Fig. 9) and the instantaneous amplitudes of the left and right halftone dot signals are proportional to the difference between the black vertex 193 and the instantaneous amplitude of the sawtooth signal 190. However, the peaks of this signal are clipped by Zener diode 425 for a large part of each period t. That left and right halftone dot signals exist accordingly! during the various periods t from a component in the form of a trimmed triangle, which is a DC voltage component is superimposed.

The consequence of the direct voltage component is that the bands 225 # 225 'are already off the center line at the beginning of each period t 242 are deflected, but are still located within the ends of the aperture slit 223. During the first part of the Period, the bands become continuous by the increasing amplitude of the triangular component of the halftone dot proper further deflected so that the ligaments soon over the ends of the

009832/0775

Get out the slot opening. The bands then remain during the middle part of the triangular component of the signal! outside the slot ends until the amplitude of the triangular j component of the signal during the last part of the period! sinks again and the bands migrate inwards again over the ends of the slit opening until they finally assume the starting position determined by the direct voltage component of the halftone dot signals at the end of the period. ^!

As a result of the described deflections of the bands draw-; net the beam 217 on the film 61 on a sequence of octagonal black raster points 266, as they are shown in Fig. l6b ■ shown . The halftone dots 266 fill each of the associated zone 257 almost completely and they are each, both with the adjacent halftone dots of the same track as disclosed with the notify \ grid points in the adjacent tracks in connection.
The grid points shown in Fig. 16b thus form together

a continuous black field containing small white recesses 267. In terms of tone density, this pattern represents the inverse of the screen pattern shown in FIG. 14b, since
a conversion of the black raster points 266 into white areas (with a certain change in position) results in the white areas in FIG. 14b and the reversal of the white spaces 267 into black
(with a certain change in position) results in the black raster points 26O in FIG. 14b.

In FIGS. 14b, 15b and 16b, the center points of the surfaces of the grid points coincide with the center points 262 of the associated
Zones 257 together, that is to say they assume their normal position with respect to these surface centers.

A comparison of FIGS. 14b, 15b and 16b with FIGS. La, Ib
and Ic shows that the elek- shown in Figs. 14b to 16b. troniach generated halftone screens largely with those in the
Fig. Ia to Io shown photographicch generated halftone \ match rasterize. With the help of the inputs shown in ^FIG. 2 direction can therefore an original into an electronic half-tone j baths raster image implement the halftone dot structure with derjeni-, gene virtually matches the one in photographic herstel-j development of the halftone image by a conventional Grid plate received j

009832/0775

Ί 772022

Acentric shift in clay density gradients

Up to this point, the friction was limited to cases in which the scanned tonal values in the original were uniform on both sides of the center line 137 (FIG. 7) of the scanning area 135 and, accordingly, also from the left and right halves 139; or 139 'of the spot I30 halftone dot signals of the same amount i were generated, which cause purely centric deflections of the bands 225,: 225' of the light lock. With such scanning conditions ι no double scanning device is required, which resolves the rectangular spot 130 into a left and a right half. Rather, the raster dot patterns shown in FIGS. 14b to 16b can also be recorded on the film 61 by a simple scanning device which converts the light from the entire width of the slit spot 130 into an image signal which is processed in only one channel 150 or 150 ^f and then fed to the bands 225, 225 ^f with different polarities in order to deflect these bands in relation to one another as a function of the signal amplitude. The division of the spot I30 into a left and a right half and the division of the electronic circuit into a left and a right channel for separate signals from these spot halves, however, play an important role for the function of the device shown in FIG. 2, as will now be explained since this subdivision enables tone density edges to be smoothed in the reproduced halftone screen image. In this connection, reference should first be made to Fig. 17, which shows both an original image and a halftone reproduction of this image by means of a photographic raster plate. The line 280 in Fig. 17 represents a Tondichtegrenze original between an upper left white area and a lower right black area. In the reaction of the original in <the halftone image by means of a grid plate, the limit 28O by a distribution of grid points at the transition between an upper left halftone dot pattern 281 corresponding to white and a lower right halftone dot pattern 282 corresponding to black. Along this transition there are grid points 224, 285 of medium size, which are completely or partially separated from the black grid point pattern 282. At the transition between the BföföF & erolpJffiPe ^ l and 282 also occur

Typically indentations 286 that go deep into the black grid * Puster into it, and corresponding projections 287 of the blackens zen grid areas that protrude into the white grid area,

! on. So if the originally sharp boundary 280 is photographed is reproduced using a grid plate appears

! the reproduced border as an irregular and frayed zone between the white and black halftone patterns 281 or and not as a sharp boundary line.

■ In the illustrated in Fig. 2 means a sharp Tondichtegrenze of the original image in the halftone image is substantially reproduced smoother than the irregular boundary in Fig. 17. This advance is achieved in the device described, characterized in that the bands 225, 225 'of the light lock in independent correspondence the brightness of the toes or right half 139, 139 'of the slit-shaped spot I30 are controlled and that, secondly, measures are provided to supplement the left and right field signals described above with signals for an acentric deflection, which deflects or shifts both bands in in the same direction.

The optimal displacement ι for the respective conditions is shown in FIGS. 18 to 21 on the basis of four tone density limits with ^! different course, as they can occur in the original 60, • shown. The four cases shown are: the tone density limit runs from right to left and advances from white to black in the direction of the scan (Fig. 18), the tone density limit runs from left to right and advances from black to white in the scanning direction (Fig 19 ) " the tone density boundary runs from right to left and advances from black to white in the scanning direction (Fig. 20) and the tone density boundary runs from left to right and advances from white to black in the scanning direction (Fig. 21). To simplify the description, it is assumed for FIGS. 18 to 21 that the areas on the opposite sides of the tone density boundary are black and white, respectively, so that the contrast between the areas of the original 60 located on the two sides of the boundary has its greatest possible value. Cases in which the tone density jump at the border does not correspond to the maximum contrast,

009832/0775

will be covered later.

In Figs. 18 to 21, a displacement line 290 is in 'That part of the original 60 is drawn which generates such a displacement line. Line 290 represents the optimal Transverse displacement or decentration deflection of the band gap center 241 from the slot center 242, which leads to the through the left and ! Right field signal in the main deflection sections 160, 160 '(Fig. 8 the distractions caused by the ligaments. Figs. 18 to 21 show that the line of optimal displacement following El- : has properties:

First, the shift is always in the direction of the dark side of the boundary 289.

Next, consider the moving areas of the left and right stripes I38 and 138 ^{1 of} the scanning track 125, which are simultaneously scanned by the left and right halves Ij59 and 139 ^{1 of} the elongated spot I30 along the track I35 and which these Track intersecting tone density boundary 289 included. Note that a selected strip 1 ^ 8 or I38 ^{1 is} a "reference strip" which, over its length, gives a wider scanned portion than the other "compared ¹ * strip. The second feature is that the line 290 shift shown does not occur, while the average tonal value of the scanned area de »compared strip varies, but during the change in the average tonal value of the off W keyed portion of the reference strip. j

For example, in the case shown in Fig. 18, the left is | Strip Ij58 the reference strip and a shift 290 occurs in the length interval of the track I35, in which the boundary 289 intersects the compared strip I38 ¹ and detected by the left half 139 of the patch I30 mean tone value accordingly advanced 'is continuously darker. However, there is no shift in the length interval in which the boundary 289 crosses the reference strip I38, although this results in a continuous change in the mean tonal value detected by the right half of the spot 1J50.

009832/0775

In the example shown in FIG. 20, the right stripe 138 ^{1 is} the reference stripe and there is no shift 290 in the length interval of the track I35 in which the boundary

289 crosses the reference stripe and causes the mean tone value of the half of the scanning spot moving in this stripe is detected, becomes continuously brighter. A shift

On the other hand, 290 occurs in the length interval in which the limit 289 crosses the compared strip and has the consequence that the mean tone value detected by the scanning area in this strip becomes continuously lighter in the mentioned interval.

As a result of the second ^ explained above by means of examples Thirdly, the displacement line 290 extends in ™ Scanning direction in the scanning track 135 only via the compared Stripes crossing portion of the tone density boundary 289. In addition, the displacement line has endpoints that are in the length of the track 135 correspond to those points where the boundary 289 the outer edge 136 of the compared strip or the center line 137 of the scanning track intersects.

Fourth, the displacement 290 reaches a maximum or one between these zero displacement points Tip halfway between the mentioned endpoints. At this point the scanned area is the compared strip half white and half black and therefore appears as medium gray. f

Fifth, the maximum displacement is equal to half the width of the strip being compared.

FIGS. 22a to 22c show variants of those shown in FIG Sample ratios, with the limit from right to; runs to the left and the scanned tone value is in the scanning line! changes from white to black. '

In Figure 22a, the tone cutoff limit 289 intersects the sample | trace at a more acute angle than in Fig. 18. A comparison of Figs. 18 and 22a shows that the displacement line 290 in both] Cases has a length calculated in the scanning direction that corresponds to the Distance between the points at which the boundary 289 is the outer Edge I36 of the compared stripe I38 or the center line

009832/0775

137 of the scanning track I35 intersects. Line 290 is in Figure 22a longer than in Fig. 18, since the trace 135 through the boundary 289 in is cut at a more acute angle than in FIG. 18. The length of the displacement line 290 is thus a function of the angle between the tone density limit and the longitudinal direction of the scanning track, with which this limit is scanned.

Neither the size, nor the shape, nor the position of the displacement line 290 are a function of the position (spatial phase) of the raster point zones into which the scanning track I35 is subdivided. In particular, the size, shape and position of the displacement line 290 are independent of whether the track is divided into zones whose boundaries W are denoted by 255 or in zones denoted by boundaries 255 'which are spatially 180 ° with respect to the first-mentioned zones (or any other amount) are shifted in phase.

In FIGS. 22b and 22c, borderline cases are shown in which the tone density limit 289 coincides with the center line I37 of the scanning track 135 coincides or the scanning track through the boundary 289 is crossed vertically. In neither of these two cases does a shift occur.

The above statements with regard to the variants shown in FIGS. 22a to 22c of the case shown in FIG Of course, it can be applied analogously to the corresponding variants of the cases illustrated in FIGS. 19, 20 and 21.

Generation of the decentralization signals

In the device shown in FIG. 8, the deflections of the strips 225, 225 'of the light lock (FIG. 10) corresponding to the displacement lines 290 are controlled by a left and a right decentering signal generator unit, the secondary branches 162 and 162' in the left and right channels, respectively Form I50, I5O ¹ . The left decentration signal generator unit contains a left-right signal comparison stage 300 and a minimum signal selection stage 301. The right decentration signal generator unit accordingly contains a right-left signal comparison stage 300 'and a minimum signal selection stage 30I ¹ . The decentering ί

009832/0775 BATH ORIGINAL

I Signal generator units only work if the strip-shaped \ Äbtastfleck 1 ^ 0 has a tone density limit or a tone density gradient! that is sufficiently pronounced to produce a difference between the mean tonal values of the areas of the scan strips Ij58, 158 'scanned by the various halves of the spot 130. When such a difference occurs, only one of the decentration signal generator units is energized in order to generate a decentration deflection signal. Which of the two units is excited depends on the course of the tone density limit that is scanned by the spot 130, that is, on which of the cases shown in FIGS. 18 to 21 is present.

Tone density limits as shown in FIGS. 18 and 19 cause the right unit 162 ^{1 to be} excited, while tone density limits of the type shown in FIGS. 20 and 21 cause the left unit 162 to respond.

When the right unit 162 ^! is excited, it supplies two similar right decentration deflection signals via lines 502, 303 to the adding stages a iuC and 200 'in the left and right channels I50 and I50 ¹ , so that these decentration deflection signals are added to the left and right raster point signals in these channels. The right decentration deflection signals generate current components which flow through the ribbons 225, 225 * of the light lock 100 in the same direction. Each of these current components causes a rightward component in the deflection ™ of the corresponding band. When the left unit 262 is energized, it provides similar left decentering deflection signals over lines 302, J0} to the left and right adders 200 and 20O ^1, respectively. The two left decentration deflection signals allow current components to flow in the bands 225, 225 * which have the opposite direction to the ^{current components generated by the unit I62 1} and each generate a leftward component of the deflection of the corresponding band. The effect of the current components of the left decentration deflection signals is thus a leftward deflection of both bands.

The Dezentrierungssignalgeneratoreinheiten 162 and I62 corresponding to the Koenen ¹ in Fig. Circuitry shown 2j> be constructed, in particular, the left-hand comparator stage 300 '

ί I U / '0

and shows the minimum signal selection stage 30I ¹ . The comparison stage 300 'contains two phase splitter stages 305 * 306 equipped with semiconductor components, both of which are supplied with DC operating voltage (eg + 12V) via a common circuit point 307. The stage 305 contains an NPN transistor 308, a resistor 309 connected between the node 307 and the collector of the transistor 308, a resistor 310 via which the left field signal V _{L is} supplied from a line 311 to the base of the transistor 308, and a Resistor 312, via which the right field signal V _{R is} fed from a line 313 'to the emitter of transistor 308. The stage 306 contains an NPN transistor 314, a resistor 315 connected between the collector of this transistor and the node 307, a resistor 316, via which the right field signal V _R from a node 304 of the base of the transistor 314 connected to the line 313 ¹ is supplied, and a resistor 317, via which the emitter of the transistor 314 is connected to an operating voltage terminal 318 (eg -6V).

The minimum signal selection stage 30I ¹ contains two NPN transistors 320, 321, the base electrodes of which are connected to the collector of the transistor 308 in the phase splitter stage 305 and the collector of the transistor 314 in the phase splitter stage 306, respectively. The collectors of the transistors 320, 321 are connected to a terminal of an operating DC voltage source (for example +12 V) via associated resistors 322 and 323, respectively. The emitters of the transistors 320, 321 are connected to a second operating DC voltage terminal (eg -12 V) via a common resistor 325. The output signal of stage 3OI ¹ is available at the connection point of the emitters of transistors 320, 321 with resistor 325 and is fed to two parallel-connected PNP transistor amplifiers 327, 328 of conventional design via a line 326 and an intermediate PNP amplifier transformer (not shown) deliver the same right decentration deflection signals via lines 302 'and 303 * to the adder 200 in the left channel I50 or the adder 20O ¹ in the right channel I50 ¹ j.

005832/0775

The voltage V i at the base of the transistor 320 is equal to the constant voltage (+12 V) at the node 507 minus any voltage drop V i that arises from the operation of the phase splitter stage 305 at the resistor 309. Correspondingly, the voltage V. «at the base of the transistor is equal to the constant operating voltage (+12 V) at the node 3507 minus the voltage drop Vp that occurs across the resistor 315 due to the phase splitter stage 306 working. The step ¹ is a 3OI the largest voltage dialing device in the sense that the output voltage on: line 326 to that of the voltage V, or V, p corresponds to; has the greatest positive value for mass. However, if one considers stage 301 'with regard to its control by the voltage drops V. and Vp across resistors 309 and 315 *, then this stage selects the lower of these voltages, since V _{bl is} inversely related to V ₁ and V _b _ inversely V _g change. So if V _{1 is} less than I than Vp, the output on line 326 is V. ..; concatenates and follows any fluctuations in V ₁ , but if V: is less than V ₁ , the output on line 326 j is concatenated with V, ρ and follows any changes in Vp.

If the voltage drop is viewed as a positive variable, then the changes in the output voltage on the line 326 are proportional to the amount, but in the opposite direction to that of the voltage drops V or Vp, which the output voltage always follows. For example, if the output voltage _{follows voltage V 1} and V _{1 increases} from 0 to 2 volts, the voltage on line 326 decreases from a reference value by an amount proportional to the 2 volt change in V ₁ and delivers at this drop a right decentration deflection signal which reflects _{the change in V 1.} The size of the right decentration deflection signal is therefore always practically proportional to the size of that of the voltage drops V ₁ or V _g that the signal is currently following.

To explain the operation of those shown in FIG The unit as a whole should first consider the operation of this unit in a state situation as shown in FIG will. As long as the slot-shaped spot 130 does not yet move in the scanning track 135 during its downward movement

0ÖÖ832 / 0776

Part of the tone density limit 289 has detected, the input signals V _L (left field _{signal) and V R} (right field signal) of the stage 300 'are the same and they have a value of, for example, 0 volts. There is then no voltage difference between lines 3II and 313 ¹ , transistor 308 does not conduct significantly and the voltage drop V ₁ across resistor 309 is then practically 0. On the other hand, however, the voltage difference between voltage V _R on line 313 ¹ and the operating voltage (-6 volts) at the node 318 their maximum value (-6 V), so that the transistor ^ 14 conducts and a maximum voltage drop V ₂ (6 V) occurs at the resistor 315. These limit values (0 V or 6 V) for the voltage drops V. and Vp correspond in FIG. 24 to the left end points 330 and 331 of the lines 332 and 333 shown V _R if V, = 0 V or the size of V _? as a function of V _R when V _L = 0 V on.

When the slit-shaped spot I30 in FIG. 18 moves further down the track 135, it first reaches the tone density limit 289 where it crosses the right edge I36 of the track 135. With the further downward movement of the spot, the left half 139 of the spot in the reference strip I38 continues to scan a constant white tone value. In this interval, the signal V _L therefore remains constant at 0 volts. In the same interval, however, the right half 139 * of the spot detects in the "compared" strip (I38 ¹ ) a mixture of a black and a white area, which are separated by the inclined border 289, with I30 as the spot moves downwards along this interval the sizes of the white and black areas continuously increase or decrease.

The phototransistor 144 ^f (FIG. 6), on which the light falls from the right half of the spot 139 ', does not distinguish any tonal value details within the spot half 139'. ^{Rather, it delivers a signal V 1} , which corresponds to the integral of the intensity distribution in the area covered by the spot half I39 1. In the interval in which the boundary 289 ^{crosses the strip I38 1} , the signal V _R accordingly decreases continuously from 0 to -6 V. This change in the value of V _R is shown in FIG. 24 along the abscissa.

006832/0776 BADORiGINAL.

carried.

The progressive decrease in V _n corresponds to a progressive increase in the difference between V ₁ . and V _n and one

Li K

the difference between 'V _n and the

ti

Voltage of -6 V at node 318. As V _n decreases,

ti

the voltage drops V ₁ and V _n therefore increase or decrease in a corresponding manner until at the end of the mentioned interval V. has assumed its maximum value of 6 V and Vp has dropped to OV (point 334 in Pig. 24).

As mentioned, in Fig. 24 by the lines 232 m and illustrated the changes of V. V ₂ are illustrated and as a function of V _R with V _L = O 233rd These two lines intersect at a point 335 # which corresponds to a point 336 on the abscissa, at which ν., Equals -3 V, that is, lies in the middle between the initial value of OV and the final value of -6 V.

As explained, the selection stage 301 ¹ supplies a right decentering deflection signal on the line 326, the amplitude of which _{follows the changes in the smaller of the signals V 1} and Vp. Thus, while the slit-shaped spot 130 in the track 135 passes through the interval in which the right stripe I38 is crossed by the boundary 289, the size of the signal on the line 326 increases first as it follows the rise of V. that of a movement corresponds to the right along the lower part 337 of the line 232, then the size of the signal on the line 326 reaches a maximum value which corresponds to the point 335 and finally the size of the signal on the line 326 decreases again by the Drop in voltage V _? follows, which corresponds to a progression along the lower part 338 of the line 333 to the right.

In other words, the right decentering deflection signal undergoes a triangular amplitude change while the slit-shaped spot I30 passes through ^{the interval in which the boundaries 289 cross the "compared" strip 138 1.} This triangular change in amplitude corresponds to point 330, line segment 337, point 335, line segment 338 and point 334 in FIGS

009832/0775

Pig. 18 is shown. The requirement that the shift at the maximum of the shift line 290 is equal to half the width of the strip 1 ^ 8 'is made possible by setting the right decentration deflection currents which the bands 225, 225 ^! by- . flow adjusted with respect to the size of the output signals on the lines 302 ', Z> oy.

After the slit-shaped spot I30 scans the interval of the track 135 in which the boundary 289 crosses the "compared ¹¹ stripes 1 ^ 8 ', the spot I30 scans a second interval in which the boundary 289 crosses the reference stripe 138. During this Throughout the second interval, the signal V _{R is} equal to -6 V, so that the voltage difference between V _R and the node 318 is equal to zero and the voltage drop V _{3 is kept} at the value 0. As described, however, the amplitude of the right decentration deflection follows from of the stage JO I ^{1 is} the smaller of the signals V _{1 and V 3.} During this second interval, the amplitude of the right decentration deflection signal is therefore kept at the value zero and no shift 290 \ occurs.

In the case shown in FIG. 19, the order of the processes which are used to generate the right decentration deflection | The reverse of the sequence of operations described in connection with FIG. 18. In FIG. 19, the slit spot 130 in the track 135 therefore first scans an interval in which the boundary 289 crosses the reference strip 138, the mean tone value in the scanned area of this strip changing from black to white. The simultaneously scanned area in the "compared" strip 138 ¹ is consistently black over this entire interval. The spot I30 then scans a second interval in which the stripe 138 is constantly white, while the mean tone value of the scanned area of the stripe 138 ^{1 changes} from black to white. During the first interval, the signal V _R remains at its minimum value of -6 V and thereby keeps the amplitude of the right decentration deflection signal at the value 0, so that no shift 290 can occur in this interval. In the second interval, the signal V _{R increases} from -6 to zero V. This progressive increase in the

009832/0775

Signal V _R causes the voltage drop V _? changes from 0 volts to 6 volts, while at the same time the voltage drop V ₁

I drops from 6 volts to 0 volts. During this second interval, therefore, increases the amplitude of the right Dezentrierungsablenksignales on lines 302 ', 303' first, since this signal follows \ the amplitude rise of Vp, which corresponds to a movement along the lower part 338 of the line 333 (Fig. 24 and 25) corresponds to the left, then this signal reaches a maximum, which is represented by the ' point 335 and finally the amplitude of the signal drops again, since it _{follows the amplitude drop of V 1} , which follows a port stride along the lower part 337 of the line 332 corresponds to the left. %

The right decentration deflection signal makes a triangular change in amplitude during this second interval by which, although they are carried out in a different order than the one in Pig. l8 generated case is substantially equal to the triangular change that occurred when the boundary shown in FIG. 18 was scanned occurred. The signal change which occurs when the tone value limit shown in FIG. 1 is scanned, generates a displacement line 290 as shown in this FIG.

In FIG. 20, the strip I38 is consistently black in the interval in which the boundary 289 crosses the strip I38 'and provides a signal V-. minimum value that the decentration deflection signal of the right decentration signal generator unit 162 ^! holds at the amplitude value 0 throughout this interval. In the following interval, in which the boundary 289 crosses the strip 138, the signal V _{R is} always greater than the signal V _T and the transistor 3Ο8 is blocked, so that V ₁ and thus also the right decentration deflection signal are held at the value . In the circumstances shown in FIG. 20, the right decentration signal generator unit cannot deliver an output signal.

In the case of the sampling ratios shown in FIG. 21, the unit 162 'cannot supply an output signal either for the following reasons: While the spot I30 scans the interval in which the boundary 289 crosses the strip I38, the is

009832/0775

BATH ORIGINAL

Stripe 138 'is constantly white, so that the generated signal V _D

is always greater than the signal V _L. In this interval the transistor 308 is therefore blocked, the voltage drop V. remains 0 and the output signal of the unit is kept at the amplitude value 0. If the spot I30 then scans the interval in which the boundary 289 ^{crosses the strip 138 1} , the signal V _R remains greater than the signal V _L and the output signal of the generator unit is thereby kept at the amplitude value 0.

So far, only the response or non-response of the right decentering signal generator unit 162 'when scanning tone density boundaries between black and white areas which result in a maximum jump in contrast at the boundary has been discussed. It is now assumed, however, that although the darker side of the boundary 289 remains maximally black, the lighter side, on the other hand, is one step grayer than the white tone shown in FIG. In this case, the signals V ~ _L and V _R before the scanning of the boundary 289 intersecting the track 135 no longer have the value of 0 volts specified, for example, but rather both, for example, the value of -1 volt. The change in V. as a function of V _R then corresponds to a line 3 ^ 1 (FIG. 25) which intersects the horizontal coordinate at a point 340 which represents the value of -1 volt for V _R. However, line 333, which represents the change in Vp as a function of V _n , remains the same except that this

Line now has a left starting point 342 which is on the horizontal Coordinate corresponds to the value of -1 volt and on the vertical coordinate to a value of 5 volts for the voltage drop V «. In the case under consideration, the triangular change in the size of the right decentration deflection signal in Fig. 25 is represented by the triangle which is formed by the point 340, the line 341, the intersection point 342 with the line 333 * the part of line 333 lying to the right of point 342 and the point 334 is defined. This triangle has a smaller base than the triangle defined by points 330, 335 and 334, However, it does not follow from this that the distance between the end points of the resulting displacement line 290 is smaller than that shown in FIG. 18 shows. On the contrary, this distance remains the same and the maximum

009832/0775

BATH ORIGINAL

ι mum the distraction occurs, as before, in the middle between the Endpoints. The only difference that comes when the lighter side of the border 289 is one level grayer than that white tone shown in Fig. 18 is that the amount of maximum deflection is slightly smaller than that of the pure white tones.

In FIG. 25, the triangle defined by points 35O, 351 and 3 ^ 4 represents the change in the size of the right decentration deflection signal when the tone value on the lighter side of boundary 289 is still one level grayer than white, so that the signals V. _1st and V _n both have the initial value -2 volts. As before, the resulting displacement line 29O has the same endpoints ^ as in FIG. 18 and a peak lying between these endpoints, but the amount of deflection at the peak is even smaller than with a tone value which is one level grayer than white. It is evident by extrapolation that, regardless of how large the deviation of the tone value on the lighter side of the limit from white, the unit shown in FIG. 23 when scanning a tone value limit as shown in FIGS. 18 and 19, a triangularly changing right decentering deflection 29O is generated in the interval in which the boundary crosses the right strip 138 ^{1 of} the scanning track I35.

It should also be pointed out that the right Dezentrlerungssignalgeneratorelnheit I62 ¹ also produces a right similar-looking Dezentrierungsablenkung 290 when the brighter side of the border white, but the darker side is not full black. The same is true if both the lighter side of the border are darker than pure white and the darker side of the border are lighter than maximum black. Even if the tone density gradient between the lighter and the darker area is not as sharp as it is shown in FIGS. 18 to 21, the unit 162 'provides a decentration deflection signal.

The circuit of the left decentration signal generator unit 162 'corresponds to the right unit 162' with the following exceptions: First, the connections for the signals V _L and

V_ in the left unit compared to FIG. 2J> interchanged, ie that R

009832/0775

V _{R is applied to} a resistor corresponding to resistor J10 and V- to a node corresponding to junction 304 between resistors 512 and 316. Second, the amplifiers 327 and 328 are located in the left-hand unit 162. speaking amplifier NPN transistor amplifier and not PNP transistor amplifier, so that the amplitude changes of the left decentration deflection signal on lines 302, 303 (Fig. 8) run in the opposite direction as the amplitude changes of the right decentration deflection signal on lines 302 ', 303'. The left unit 162 * works symmetrically to the right unit I62 ¹ , that is, the unit 162 responds when scanning tone density limits or transitions of the type shown in FIGS. 20 and 21 and the deflections directed to the left ^! causes the band gap center 241, which are shown in these figures! are drawn, while the left unit on the other hand in the in; 18 and 19 can not cause a distraction. However, since the modes of operation of the two units are symmetrical, the left unit 162 speaks to a tone density limit of the in! FIG. 21, analogously to the right unit I62 ^1, to the scanning of a tone density limit of the type shown in FIG. In the same way, when scanning a tone density limit of the type shown in FIG. 20, the unit ^{on the left responds analogously to the right unit I62 1} to the scanning of a tone density limit of the type shown in FIG. 18.

Halftone rendering of tone density boundaries

27 to 30 belong together and show the generation and properties of the halftone boundary recorded on the film 61 by the described device when a tone density boundary 289 of the type shown in FIG. 18 is scanned in the original 60. FIG. 27 practically corresponds to FIG. 18. FIG. 28 corresponds to FIG. 9 and shows, by means of the lines 36O and 36I, the changes in the level of the right field signal V _R and the left field signal V 1, respectively, while the slit-shaped spot I30 in the track 135 (FIG. 27) scans the tone density boundary 289 .

29 shows the halftone boundary 365 which is created on the film 6l by the effect of the gap width control by means of the light

009832/0775

sluice bands 225, 225 'would be reproduced on the exposing light beam 217 if these bands were only generated by the signals V _T and V _R in the main control paths 160 and 160 ^! (Fig. 8) would be controlled, that is, if these bands are not fed ^{decentration deflection signals from the unit 162 1.} In the same figure, the boundary 289 is drawn as it would look in a perfect reproduction. In FIG. 29, the displacement line 290 also shows the decentration deflection component which corresponds to the right decentration deflection signal generated ^{by the unit 162 1.}

Fig. Yd shows, compared to Fig. 29, the halftone boundary 366 as it is reproduced when the deflections of the bands ^ by the signals V _T and V _R in the main deflection paths 160 and 160 'as well as by the right decentration deflection signals, the! generated by the right decentration ^{signal generator unit 3.62 1} on lines 302 ', 303'.

; The limit shown in FIG. 29 can be constructed graphically from the diagram shown in FIG. 28: in the following manner for the period t of the cyclic sawtooth signal I90. As already described, the right deflection control comparator 165 ^f does not provide a right raster point _{output signal when the level of V n is} greater than that of the sawtooth signal. If, however, the level of V _R intersects the sawtooth signal at point 369 and becomes smaller than the sawtooth signal, the comparison stage 165 supplies ¹ | a halftone dot signal which deflects the right band 225 'proportionally to the respectively prevailing difference between the level of the signal V _R and the magnitude of the sawtooth signal I90. The value of this difference is shown in FIG. 28 for various points in time in the first half of the period t by the lengths of arrows 370, 371 and 372. During this first half of the period t, the boundary 365 in FIG. 29 coincides with the location 374 of a number of diagram points which each correspond to one of the arrows 370 to 372 in that the point in question has the same vertical position as the corresponding arrow and with respect to the center line 255 is offset to the right by a distance corresponding to the length of the associated arrow. For example, point 369 * and points 370 ', 371' in FIG. 29 correspond to the point

00Ö832 / 0775 ^BAD

369 and arrows 370, 371 in Fig. 28. The rest of the border can be obtained by the same graphic method as just described. It can be seen that e.g. the diagram point corresponding to arrow 372 outside the scanning track 250, i.e. to the right of the right edge 25I of the track 250, since the band deflection corresponding to arrow 372 is so great that the middle part 230 * of the band 225 'over the right end of the Aperturschlitzes 223 (Fig. 12b) is deflected outward.

In the first half of the period t, the signal is V ₁ , except for

the last end greater than the sawtooth signal I90. During the For the greater part of this half period, the left band ^ 225 remains undeflected. The band gap center 241 is from the center 242 of the aperture slit by half the width of the deflection of the central portion 230 'of the right band 225' from the center 242 of the aperture slit, that is, deflected to the right by half the width of the band gap 240.

It is therefore possible to generate an acentric deflection as defined above without the participation of any decentering deflection signals from the units I62, I62 ^1. That this is possible is due to the fact that the left and right bands of the light lock can be controlled independently of one another by separate field signals obtained from the left and right sides of the scanning track 135, respectively. The acentric deflection caused by the field signals alone can be explained by dividing the total deflection of each band into a centric and an acentric component. In the left band, these two components are directed in the same way but in opposite directions, so that the total deflection for the left band is zero. In the right band, however, these two components are equal in amount and direction and add up. Since both types of components are actually present, they result in both a centric deflection of the belts symmetrical to the belt gap center 241 and an asymmetric decentering deflection of the belt gap center with respect to the slot center 242, although the total deflection of the left belt 225 is zero.

During a short interval at the end of the first half of the period t, the sawtooth signal exceeds I90 for the first time

009832/0775

BATH ORIGINAL

the level 36I of the signal V ^. During this short interval the left band 225 therefore begins to move to the left, as shown by the illustrated portion 375 of the boundary 365 in FIG.

During most of the second half of the period t, the instantaneous value of the sawtooth signal I90 is substantially greater than the level 360 of the signal V _R , so that the right band 225 'is deflected over the right end of the aperture slot 223 during this entire half of the period , with the exception of the last end of this half-period, where the right band moves inward enough to form the upper left edge of the small white recess 267. In the same half period, the voltage difference between the sawtooth signal 190 and the signal V _{L is} characterized by a continuous linear increase, as the continuously increasing lengths of the arrows 376, 377 (FIG. 28) show. The reproduced tone density limit 365 therefore has a straight portion 378 directed to the left during this second half of the period t.

The course of the border 365 in the grid dot zone shown in full 257 is of course repeated in zones 257 * which are located diagonally above and below the fully depicted zone.

The dashed line 38O in Fig. 29 shows the size and shape of a black karoförmigen grid point as in the zone 257 by either a grid plate when imaging the like in Fig. Tone limit or 27 shown by the described device when scanning a uniform medium gray tone (Figures 15a and 15b) would be generated. The raster point 381, which is generated by the described device when scanning the tone density boundary 289 (Fig. 27) of the original without the decentration deflection signals from the unit I62 ¹ , differs from the raster point 38O in the following respect: First, the area center point 382 of the raster point 38O is related shifted from its normal position on the center line 255 (and the zone 257) in the direction of the dark side of the boundary line 289. As shown in FIGS. namely, they are located at the intersections of a

009832/0775

- 48 - - 177202? .

Grid formed by a first group of equidistantly parallel lines and a second group of lines running parallel to one another at equal intervals, which line the lines of the first group under right, Cutting angles, is formed The scanning of a tone density gradient (which in the borderline case consists of a tone limit) in the present device has the effect that the area centers of the reproduced grid points in the direction to the black side of the gradient and away from the points occupied by the center points in the normal smooth surface pattern.

A second difference is that it actually does formed raster point 381 no longer checkered like the raster point 380, but in a first approximation dreleokfOmIg and on the lower right diagonal half of zone 257 is concentrated. Sines The main features of this change are that the grid point 381 in comparison to the grid point 38O is in the direction of the The course of the original clay density gradient has been lengthened and therefore has a larger maximum dimension in this direction (between points 384 and 385) than the maximum dimension of the spot (between points 389 'and 386) in the direction of the gradient, ie in the direction perpendicular to Limit 289. Due to this extension and the formation of an edge section 365 in the zone 257 with one of the boundary 289 in a first approximation, the reproduced section 3 ^ 5 at j visual observation to be able to refer to the corresponding

1 given edge sections in the diagonally above and below the fully illustrated zone 257 and the sequence of edge sections accordingly has an uninterrupted appearance.

The described change in the shape of the halftone dots 38I and the shift of its center point thus results in a tone density limit of 365 # in the reproduction, which is a good approximation! represents the ideal limit 289. The reproduced tone density limits | ze 385 does not exactly agree with the ideal limit 289, but the agreement is much better than with a re-' would give through the raster point 380. On a larger scale, the reproduced border 385 agrees a lot with the ideally reproduced border;

009832/0775

better matched than the jagged border between white and black (Fig. 17) * as is the case when reproducing a tone density border of the original by means of a grid plate. The reproduced border 385 looks very similar to the original one Border 289 (FIG. 27) is sharp and clear and not blurred like the jagged border shown in FIG. 17 is.

In the absence of the right decentering deflection signals from the unit 162 ', however, the reproduced boundary 365 (FIG. 29) i has a pronounced projection 390 which is adjoined by an indentation 391. The effect of the combination of the right decentration M '■ deflection signals with the signals V, and V _R in the Hauptablenkstrek-. ken 160, 160 ^f (FIG. 8) is shown in FIG. The raster point shown in this iFigure was obtained graphically from FIG. 29 by adding the displacement represented by the displacement line 290 to the transverse displacement of the boundary 2β5 of j of the center line 255. As FIG. 30 shows, in the reproduced tone density limit 366 represented by the signals V _1. ,

Xj i V _R and the right decentration deflection signals was generated, the! Projection 395 is substantially smaller than the projection 391 and the indentation 392 is substantially smaller than the recess 390. The line 366 therefore provides an even smoother halftone reproduction of the original boundary 289 (FIG. 27) is as the boundary 365 ^in! Fig. 29. i

3I to 34 together show how the described device reproduces a tone density limit in the raster image when a tone density limit is scanned in the original, as shown in FIG. 31, which essentially corresponds to FIG. Since Figs. 31 to 34 correspond to Figs. 27 to 30, with the exception that they apply to the scanning of a tone density boundary (Fig. 31) j whose dark and light side compared to that in Fig. are interchanged, a * detailed description of FIGS. 3I to 3 ² J- can be dispensed with. These last-mentioned figures show, however, that the device described can also be used in the case of scanning a tone density limit of the tone density limit shown in FIGS. 19 and 3I represent! The type set the tone density limit in the reproduced raster image

009832/0775

as effectively as when a tone density boundary of the type shown in FIGS. 18 and 27 is scanned in the original. The facility is also capable of those reproduced in the raster image ^! To smooth tone density boundaries when in the original tone density boundaries of the type shown in FIGS. 20 and 21 are scanned, since tone density boundaries of this last-mentioned type are only reverse versions of tone density boundaries of those shown in FIGS. 19 and the operation of the device for such inverted types is symmetrical to the operation for the non-inverted types shown in Figs.

fe modifications and alternatives

A specific embodiment of the invention has been explained above. In the following it will now be explained how this one Embodiment can be modified and what other possibilities exist to put the invention into practice.

Instead of scanning positive originals 60, negative originals can also be scanned with the device shown in FIG (to a reference level relative) of the field signal in the respective channels and the Tondichtewerte in the device are between larger and smaller amplitude values represented by these W larger and smaller amplitude values effected. FIG. 2, as described above, amplitude values represent the respective field signals that are larger or smaller than the signal level for "reference black" represent a correspondingly lighter or correspondingly darker tone. This relationship is reversed by the inverter stage, so that larger and smaller amplitude values then represent correspondingly darker or correspondingly lighter tone values .

If the signals in the device according to Pig. 2 linearly with respect to their amplitude value of the tone density values, which in a negative original are scanned, the mentioned left and right inverter stages with a non-linear Transfer characteristic equipped to the existing in the negative original 60 logarithmic relationship between the tone densities

009832/0775

BAD ORlGlNAU

to compensate for the negative image and the light intensities produced by these tone densities. However, if the in Flg. 2 A logarithmic relationship exists between the tone densities sampled in the negative original and the amplitude values of the resulting signals non-linear transfer characteristic not required.

If old of the originally described facility according to Flg. 2 a positive original is scanned, or if a negative original is scanned with the device modified by incorporating the aforementioned inverter stages, a positive halftone image is obtained on the film 61 in both cases. However, the invention is of course not limited to manufacture. % mtr of positive halftone images, but can also be used to produce negative halftone images on film 61 or any other recording medium. The invention is also applicable to applications in which, for example, for the purpose of producing a negative, the formation of the notch points on the recording medium is controlled by signals obtained from the original and transmitted through three or more channels.

In the device described with reference to FIG. 2 it was also assumed that the halftone image is reproduced on the film 61 on the same scale as the original 60. Of course, any desired size ratio can be achieved between the original and the reproduced λ halftone image by synchronizing the signal generated by the line grating scanner 56 with the scanning of the original 60 and the scanning of the recording medium 61, as will be explained in more detail below:

Assume the desired fineness of the raster on the recording medium 61 is 1 / w, lines per inch (eg 100 lines per inch), so that the distance between the lines is equal to w, inches (eg 10/1000 inches). The size of an axial displacement step of the recording device 63 with respect to the recording medium 61 is then set to w ^ and the recording device 65 is adjusted so that a slot-shaped spot 220 results on the recording medium 61, the full width of which is approximately w ^ i0 £ .g 832 / 0775

- 52 - 177202?

Also assume that the periodic signal from the line grating scanner 56 (or any other Source) has a constant value t for each signal period. The periodic signal then divides each scan trace 250 corresponding to the " describes slot-shaped spot I30 on the recording medium 61 in length intervals d,., for which the following relationship applies:

(D

where S, is the linear speed with which the record carrier is moving 6l moved past the recording device 65. With this, however, these intervals in the different scanning tracks 250 square grid point zones result in 257, must d, equal to w, and therefore the following equation must be satisfied:

w.

It is now assumed that the raster image on the recording medium 61 should have k times the size of the image on the original 60, where k can be any desired number smaller or larger than 1. It follows that the magnitude of an axial displacement step of the scanning device 62 with respect to the original 60 is equal to W ₂ , where kw _{2 is} equal to w 1, and that the optics of the scanning device 62 must be adjusted so that the slit-shaped spot ljJO the width W ₂ has. It also follows that the ^peri-! sized signal from the scanning device 56 (or other source), the various strobe 1355 * which scans the spot 1 ^ 0 in the original 60 in intervals of length d is equal to _g W ₂ must subdivide j so that square raster dot zones 13 ^ result in these scanning tracks. This can be expressed by the following equations:

w _o

² > D)

kS ₂ = S ₃ (5)

009832/0775

where S _{2 is} the linear speed at which the original 60 moves past the scanner 62.

The conditions given above are those of the United States patent 3 109 888 known scanning device, in which the film for reproduction on a rotating drum, however, the original on a frame which is used for scanning the original by a light beam with respect to a scanning device reciprocated, is arranged ·. This known device can thus be used in the implementation of the invention.

The period t of the periodic signal is given by the equation _d ^

t = gi (6)

; given, where d, the total calculated in the scanning direction ! width of a black and a white stripe on the film

j is strip 50 and S, which means linear speed, with ider this strip moves past the scanner 56. I The equation that gives the conditions required for synchronism

I Draws between the scanning speeds of the filmstrip i 50, the original 60 and the recording medium 6l completely

I indicates so is

__i _ 4- 2 _ _2 tj \

^{1 3} I ^S 2 ~ ^S 3 i

however, equation (7) is subject to that given by equations (4) and (5) expressed limitations.

In equation (7), the term W- is a constant of chosen value, and from equation (4) it can be seen that the term W _{2 is} also a constant, the value of which is determined by the value chosen for the yardstick coefficient k. The quantities S ₂ and S ^ can and may be changed as long as their changes are synchronized according to equation (5). If S ₂ and S-, so change, equation (7) requires that t change synchronously, but inversely to S _p and S. The period t of the periodic signal should therefore be _{synchronized with the scanning speeds S 2} and S ^ of the original j 60 and the recording medium 61.

BATH 009832/0775

In theory, Ci ₁ can be variable and S ₁ can be variable and unsynchronized with S ₂ and S i as long as the ratio dj / Sj is equal to t. A convenient way of satisfying equation (7), however, is to keep U ₁ constant and S ₁ to be synchronized in speed with Sp and S, as is the case with the device shown in FIG.

So that the halftone dot zones in the scanning patterns for the positive 60 and the recording medium 61 are both horizontal as well as aligned in the vertical direction, as is the case with the device according to FIG. 2, must also be a synchronism of spatial phase between t and the samples of the original 60 and film 61 exist. Assume a line or track scan cycle for the original 60 start at the moment when there is a reference mark for the original, in the center of the scanning zone is for the original 60 and that a line or track scan cycle for the recording medium 61 in the same way begin at the moment when there is a reference mark for the record carrier in the center of the scanning zone for the record carrier is located. In this case, a spatial phase synchronization of the scans of the original and the recording medium is obtained, when the respective markings for the original and the recording medium are always in the middle at the same time of the respective corresponding scanning zones are arranged. If the scans of the original and the recording medium are so in are synchronized with their spatial phase, the periodic signal from the line grating scanner 56 is in spatial Phase synchronized with these samples when the · beginning of each Line or track scan cycle for the original and the record carrier coincides with a phase value of the periodic signal, which remains constant from scan cycle to scan cycle.

In connection with the above, it should be noted that there are applications of the invention in which there is the most extensive Reduction of moiré or other visible pattern effects in the reproduced halftone image may be desirable by one rigid synchronization of the spatial phase and the velocity of the quantities t, Sp and S, deviate. This may differ

009832/0775 _BAD origin «.

be effected in various ways, e.g. by changing the spatial phase and the speed ratio between ! these sizes either in a certain or in a random one Way or, alternatively, by sending the mentioned periodic (cyclic) signal in a specific or random manner - aperiodic power. A discrepancy that unites accordingly .. · the above specified possibilities is generated, results in a displacement of the surface centers running in the scanning direction of the raster points formed with respect to the normal position of these center points even if a uniform tone value is scanned in the original will. Corresponding methods can also be used when scanning a uniform tone value a transverse Displacement of the surface center points of the formed raster points with respect to the normal locations running to the scanning direction to effect these midpoints.

It should also be noted that there are applications of the invention in which the time phase of the mentioned cyclic or periodic signal can be related to the scanning of the original and the recording medium in such a way that the raster points in adjacent scanning tracks of the recording medium are in their spatial phase be shifted progressively with respect to a reference position for the grid points in the tracks. If the spatial phase of the raster points in adjacent tracks is shifted in this way, the transverse rows formed by these raster points form with those formed by the raster points in the individual scanning tracks
give way.

traces formed vertical columns angles that from 90 ° if If halftone images are to be produced with a screen angle other than 90 °, this can be done with the method shown in FIG. 2 can be achieved simply by the fact that the original 60 and the recording medium 6l on the respective Drums mounted at the desired screen angle with respect to a line on the drum that runs parallel to its axis .

The original image 60 (FIG. 2) is referred to as such because it is the graphical image that is to be used as a Halftone reproduction is scanned. Of course it can

009832/0775 bad o _R1GWL

Original image 60 can itself be a reproduction of one or more 'forerunners. The original does not have to be a photo-I graphic image also, but it can also be a trade directly 'from an object obtained photograph "for example, a Li-ve TV image, a magnetic image, etc.

Instead of the photographic film mentioned, you can even « Understandably, any other recording medium can also be used as a recording medium for forming the raster image, which result in latent or finished images. The recording medium can contain, for example, a photoresist or a sensitized one Cliché plate or the like. Exist.

Of course, the means for generating the raster image does not necessarily have to be visible light, but can consist of any stimulus emanating from the recording device and suitable on a corresponding recording medium to create an image. In the case of the present device, the image can also be transmitted through not only visible light other types of electromagnetic radiation, such as infrared or Ultraviolet radiation, by an elementary particle beam such as an electron beam, by a beam of vibrational acoustic energy, or by a magnetic flux.

The line grating scanner 56 (FIG. 2) can by another source for a cyclical signal can be replaced, e.g. by an oscillator, which is fixed or loose with the samples! of the original and the recording medium on which the raster image is generated is synchronized. Instead of the original 60 to scan in the manner described, one can also work with other scanning techniques, e.g. with a line scan or a raster scan by means of a cathode ray tube, the movement in one or both scanning directions being electronic is produced. The perception of a tone density gradient in the original can also take place in a different way than the one here in the Specifically described double scanning methods. Instead of a light lock, you can shape, measure and / or determine the position of the halftone dots in the reproduced halftone image use other gowns with the same effect.

009832/0775

BATH ORIGINAL

When types are to be reproduced in halftones with the aid of the above-described system, the tone density edges between the types and the background which result from the halftone dot reproduction are soft, as described in connection with FIGS. 27 to y \ . Therefore, the types reproduced in halftones by the system described above are better seen in their appearance than in halftones according to known methods; given types. This improvement is so great that the halftone reproduction of types which would no longer be legible according to known methods still leads to legibility according to the method of smooth edges described here. _

When printing magazines and the like in color, it is usually necessary that a copy of types on a background be reproducible in solid tones. The above-described system is suitable for such full tone reproduction in the manner described below. It should be remembered that to reproduce an image or other original with gray tones, the width of the halftone dots which are exposed on the film 61 depends on the difference between the instantaneous amplitude of the sawtooth wave I90 and the simultaneous instantaneous amplitude of the image signal. This latter amplitude can vary between a white level I91 (maximum brightness) and a black level 19p (deepest shadow). Such reference level are determined by the range and level control units I58 and I58 ¹ (Fig. 8), each of which \ for a particular scanned image of the original is set so that the resulting image signal reaches the level I9I and 19J5, if the scanned from the original Tones adopt their lightest or darkest value.

In detail, the level and gain settings on the units I58 and I58 'are made independently, so that at their outputs the image signal amplitude, which results from the scanning of the darkest point, the level 19 ^ .above the signal zero level reached and the image signal amplitude resulting from the Sampling of tone values between the darkest and the lightest scanned tone result from an image signal amplitude or extend a tone range between levels 193 and 191. Do performing such level and gain adjustments for

009832/0775 bad oz _IGMAL

an original having gray tones carries a scan of the lightest Tones, intermediate tones and the darkest tone of the original for an exposure of the film 6l (in the manner described above) in the form of a pattern of tiny black dots 260 in a white field 258 (Fig. 14b), a pattern of black dots 263 of intermediate size, which are distributed in white intermediate fields 264 of approximately the same size (FIG. 15b) and a pattern of large black dots 266 distributed between small white spaces 267 (Fig. 16b).

The reproduction of types on a contrasting background ^ can now be done in a full tone reproduction of such master copies with the system described by resetting the range and level units I58 and I58 'in the following manner or readjust. First, the level adjustment control device reset so that the signal derived from the scanning of black areas of the types has a magnitude at has a low level. Such a type black level is sufficiently below the image black level 193 * that the actual The instantaneous difference between this level and the sawtooth wave 190 is always greater than the value of such a difference, those for deflecting each of the bands 225 * 225 * of the light neck away from the center 242 of the slot opening 223 by an amount equal to half the slot width is required. This reserve " Development of the black level for the image signal results in the bands 225, 225 'outside the slot 223 during the entire Scanning of a uniform tone area of the type print so that (a) the exposure of the black dots on the Film 61 completely fills dot areas 257 and (b) eliminates any white space between those black dots. This means that the scanned areas of the copy, which Before the type areas are not mixed with the background, black in full tone are reproduced.

Another setting is to increase the gain of the image signal in the units I58 and I58 'so that the range of variation of the image signal size above a predetermined level to a bright range above the. sharpen the sawtooth wave reaches I90 and is reached by the image signal,

009832/0775

BATH ORIGINAL

when the light background of the print is scanned. From ¹ -vorgehenden Description of the light neck 100 ■ shows that with an increase of the image signal at the brightest level in the scanning of a uniform HintergrEndfläche complete blockage occurs the exposure beam 217 through the light neck 100 and thus a reproduction of the scanned area completely occurs through white areas, which represent empty spaces with regard to the points through which the print is reproduced. Therefore, scanned areas of the copy, which are undistorted background areas with other type areas, are reproduced white in full tone.

If a non-split image signal were to be derived from the light beam scanning the original, then one would Tone density edge between the print and the background in halftones because the beam would detect black and white at the same time when sweeping over an edge and would therefore lead to the formation of a gray signal. However, because the image signal in the manner described in the left and right Field signals is split and because of the use of the left and right center deviation deflection signals also already described, each reproduced tone density edge is reproduced smoothly in the manner shown in Figs. 27 to 3 ^, being perfectly regular and sharp, like the edge of a type of printing. The system described is therefore suitable also for full tone reproduction even of edges between print types and the background.

With some types of color printing (for example weft printing) it is preferred to keep residual or small dot halftone dots on the background. With these types of printing, the amplification for the image signal can ^{be adjusted by the units I58 and I58 1} so that the image signal amplitude only reaches the level IQ1 when areas are scanned which only consist of the background. With such a gain setting, the reproduced background contains small dots for the reasons described in connection with FIGS. 14a and 14b.

Often the original to be reproduced is of the type that the background of the types has shades of gray, for example one

009832/0775

^8AD original

labeled picture, where the types are darker than the rest of the picture background. In such cases, the units I58 and I58 ¹ can be adjusted in terms of the level so that an intermediate black level is set for the image signal which is achieved by the image signal amplitude during the scanning of the types and differs from the nodes of the sawtooth wave I90 by an amount which is equal to or slightly greater than the critical difference value. The units I58 and I58 ¹ can also be adjusted simultaneously with regard to the gain so that the range of the amplitude variation of the image signal above the intermediate black level extends from this level to the image white level 191. With such a setting, the dark print is reproduced in full tone, while all intermediate tones of the background are reproduced in half tones, if the image signal amplitude, which is derived from the sampling of the darkest of these tones, is less than a distance from the nodes of the sawtooth wave I90 the critical difference is.

The present invention is therefore not limited to the exemplary embodiments and modifications described for explanation, Rather, these can be changed in the most varied of ways by adding, modifying or omitting, without that thereby the scope of the invention is exceeded.

009832/0775

BATH ORIGINAL

Claims (1)

Claims 1.) Device for image reproduction, in which an original is scanned point by point according to a first scanning pattern and at the same time a recording medium with recording of the information obtained during the scanning of the original accordingly a second scanning pattern is scanned point by point, recording elements being formed on the recording medium are, which correspond in each case to information-wise assigned scanned parts of the original, and which are information-wise corresponding parts of the original and the recording are normally assigned to one another in terms of position in such a way that ™ j the centers of their surface areas are located at corresponding points ι of the two scanning patterns, gekennzei chnet by an arrangement that enables the scanning of the record carrier (6l) changes in the event of a change in the conditions prevailing during the scanning of the original (60) in such a way that the surface centers (382, Fig. 29) of the recording elements (? 8l) from the normal position (j58j5), in which the assignment to the area centers related parts (134) of the original (60). 2.) Device according to claim 1, characterized in that the displacement has a component those transverse to the direction of the point-by-point progression of the scan. f of the recording medium is directed. 3.) Device according to claim 1 or 2, characterized in that that the original is a tonal value image. 4.) Device according to claim j5, characterized in that that the shift is effected when a tone density gradient is perceived in this by the scanning of the original the shift serves to make the reproduction of this gradient on the record carrier sharper. 5.) Device according to claim ^ or 4, characterized in that that the original (6O) consisting of a tonal value image is scanned by a light spot (lj5O) becomes, which by a striking on the original and to its 009832/0775 Decomposition serving light beam is generated. 6.) Device according to claim 5, characterized in that two photo-sensitive devices (144, 144 ') are provided that the light emanating from the parts of the original, which are to the left or right of the center of the scanning spot (130), are converted into left and right signals, which in each case correspond to the scanned tone values of the original, and that the recording of information on the recording medium (6l) is controlled by the left and right signals together. 7 ·) Device according to claim 6, characterized in that the left and right signals from the left and right halves of the scanning spot can be obtained. 8.) Device according to one of the preceding claims, characterized in that the recording medium (6l) consists of a photosensitive material and that the information recorded on the recording medium the Has the form of tonal values generated by the exposure of the recording medium are formed by at least one light beam which is generated by a recording device (63) which is responsive to the change in conditions and shifts the center of the beam with respect to a reference position for that center. 9.) Device according to claim 8, characterized in that the recording device (63) has a width-controlled device is through which the illuminating light beam modulates in width according to the information which is perceived by the scanning of the original (60), the recording device recording the ten values on the Recording medium recorded in the form of raster dots, which are in corresponding raster dot zones on the recording medium are arranged. 10.) Device according to claim 4, 8 and 9 * thereby marked draws that the width modulation of the illuminating beam and the displacement of the beam center in the same Dimension direction and serve together to reproduce the original (60) 009832/0775 BATH ORIGINAL to smooth scanned clay density gradients (289). 11.) Device according to claim 10, characterized in that the dimensional direction runs transversely z \ the direction in which the scanning of the recording medium (61) proceeds through the exposing bundle. 12.) Device according to one of claims 9 to 11, d a d u r ch characterized in that the by scanning the Originals (60) perceived information is converted into an image signal, which is combined with a cyclic signal to form a Raster dot signal is combined, which is divided by the cyclic signal into raster dot intervals, each are generated by a period of the cyclic signal and each correspond to one of the raster points, and that the raster point signal controls the recording device (65) for exposing the halftone dots on the recording medium (6l). 15.) Device according to claim 11 and 12, characterized in that that the original (60) and the recording medium (6l) ir; iu 'speaking raster patterns scanned are each offset from a sequence "on in the transverse direction parallel scan lines exist and that the cyclic signal is a periodic signal whose periods with the scanning of the recording medium are synchronized, so that the exposure of the raster points on the recording medium in one predetermined pattern of halftone dot zones takes place. 14.) Device according to claim 13 # characterized that the halftone dot zone pattern consists of a number of linear orthogonal rows and columns of these zones consists. 15.) Device according to claim 14, characterized in that the reproduction of the original on the Record carrier has a rectangular outline. 16.) Device according to claim I5, characterized in that that the rows are parallel to two opposite sides of the outline. ÖÖ9832 / 0775 ^BAD original 17.) Device according to claim 15, characterized in that the rows obliquely to the sides of the outline get lost. 18.) Device according to claim 11 and 12 and one of claims IJ) to 17, characterized in that the size of the raster point signal in the raster point intervals changes from a relatively small to a relatively large value and then back to a relatively small value and that the width-controlled recording device (6j5) forms the corresponding exposed screen dots in accordance with the change in size of the screen dot signal occurring in the individual intervals by initially increasing the width of the dot and then reducing it again. 19.) Device according to claim 18, characterized in that the recording device (63) Amplitude values of the raster point signal no longer responds when they exceed a certain level, so that the middle parts of the raster points in the direction of the progress of the scanning on the record carrier with constant width to be recorded. 20.) Device according to claim I3 and 18 or I9, characterized characterized in that the change in the size of the raster point signal per interval is a size component, which is superimposed on another magnitude component which is maintained by the signal for several intervals, and that the recording device according to such ι Signal which contains the two components, a number of raster points in a scanning track on the recording medium draws corresponding to the intervals and in the scanning tracks; connected by boundaries ("necks") of finite width J are (Fig. 16). 21.) Device according to claim 18 and 19 or 20, characterized characterized in that the change in size of the raster point signal per interval is sawtooth-shaped (Fig. 9). 22.) Device according to claim 21, characterized in that the recording device (63) j 009832/0775 BATH ORIGINAL on the recording medium (6l) under control by the raster point signal recorded grid points are diamond-shaped (Fig. 15b). 23.) Device according to claim 20, characterized in that the grid points, which are along with each other Limit pieces of finite length are connected octagonally are (Flg. l6b). 24.) Device according to claim 8 and one of claims 9 to 23, characterized in that the recording device (63) contains a light lock which is arranged between the recording medium (61) and a light source (215) delivering the exposing light bundle (217) and that the shape Λ of the light beam is determined by an opening (223) which has opposite edges, the position of which can be determined by a left and a right band (225 * 225 ') of the light lock, I and that the bands with respect to a reference center ( 24l) of the opening are deflectable in order to determine the position of the center of the exposed: the bundle with respect to a reference position for this bundle. ! 25 ·) Device according to claims 12 and 24, characterized in that indicates that the raster point signal obtained from the image signal is fed to the light lock (63) and allows simultaneous deflections of the strips (225 * 225 ') away from each other to be generated during ί each raster point interval, so that the _Λ exposure of raster points on the recording medium (61) controlled by this signal. 26) Device according to claim 6 or 7 and 25, characterized in that the halftone dot signal of a left and a right component is that dui'ch association of the cyclic signal with each of the left and accounting, ten signals are formed, so that the latter signals are divided into halftone dot intervals; and that the left and right bands (225, 225 ') are controlled independently of one another under the control of the divided left and the divided right signals, respectively. I27.) Device according to claim 4 and 26, characterized in that that the scanning of a tone density 009832/0775 sad orig, _nal i gradients in the original (60) show a difference between the left one 'and the right signal generated. 28.) Device according to claim 27, characterized in that the difference unequal deflections of the right and left band (225, 225 ') generated in opposite directions from the reference center (241) of the opening (223) away, so that the center of the exposing light beam is shifted with respect to the reference center. 29.) Device according to claim 27 or 28, characterized by an arrangement (300, 300 ^f ) for comparing the ^ left and right signals with generation of a decentration deflection signal when scanning a tone density gradient (289) in the original (60), and an arrangement for controlling of the left and right bands (225, 225 ') by the decentration deflection signal so that these bands are deflected in the same direction with respect to a point which is outside the opening (223) and on a line which is substantially perpendicular through the two bands , lies. 30.) Device according to claim 29, characterized in that the decentration deflection signal has a change in amplitude which has the shape of a triangular sawtooth and a maximum at a quarter of the scan of the tone density gradient in the original, and that the change in amplitude * of the decentration deflection signal has such a polarity, that the reproduction of the gradient on the recording medium (61) is smoothed. 31.) Device according to claim 30, characterized in that the maximum amplitude of the sawtooth-shaped Change of the decentration deflection signal a puncture of the contrast is between the tone areas on opposite sides of the tone density gradient scanned in the original. 32.) Device according to claim 24 and one of claims 25 to 31, characterized in that the strips (225, 225 ') of the light lock consist of a layer structure, which contains two metal strips joined together, the first of which has a higher tensile strength than the second and 009832/077 5 BATH ORIGINAL I the second has a higher electrical conductivity than the first Has stripes. , 33.) Device according to claim 12 and one of claims Vj to 32, characterized., 'RV.ii the cyclic signal is generated by point-by-point scanning of a pattern of cyclically and periodically changing markings (51, 52) (Fig. K ). 3 ^.) Device according to claims 13 and 33 *, characterized in that the scanning of the markings (51 * 52) is synchronized with the point-by-point scanning of the original (60). μ 35.) Device according to claim 33 or 3 ^ * characterized in that that the periodic cyclic signal of an oscillatable arrangement tuned to its frequency (403 # 404) is supplied to correct temporary irregularities to filter out in the periods of this signal and to give this signal the form of an S: = -; p oscillation (Fig. 35). 36.) Device according to claim. 3 ^r % characterized by a circuit arrangement {- "C5, 4θ6) for trimming the sinusoidal signal while generating a periodic cyclic signal that indicates the crossing of a certain signal level by the sinusoidal signal, but is independent of amplitude changes of the sinusoidal oscillation with respect to this λ level . 37.) Facility in which an original image is defaced point by point is to convert the samples of the image into an image signal, and in which the original image is reproduced by a photosensitive Material is scanned by at least one light beam and the light beam is simultaneously controlled by the signal is, wherein tone values corresponding to the scanned tone values of the original are recorded on the material, characterized in that with the image signal a cyclic electrical signal is combined, which generates a raster point signal from the image signal, which by the cyclic Signal is subdivided into grid point intervals and is able to control the light beam in order to produce a number on the material 009832/0775 ' ^BAD of halftone or halftone dots each corresponding to one of the intervals. 38.) Device according to claim yj, characterized in that the cyclic signal is a periodic signal, the periods of which are synchronized with the scanning of the material by the light beam. 39 ·) Device according to claim 27 or 38, characterized in that that the scanned tonal values of the original in the halftone dot signal by the difference between one signal size determined by the scanned tone values and a cyclically variable signal size, which is determined by the cyclic Signal is obtained and one cycle of change per halftone dot interval of the raster point signal, and that the raster point signal corresponds to the width of the light beam the difference and across the direction of progression of the bundle is modulated over the material as it is scanned and that j exposed onto the material through the raster points. : 40.) device in which a cyclic periodic signal through; point-by-point scanning of a sequence of markings is obtained, | the cyclically and periodically change from point to point in the scanning direction, characterized by j is a tuned circuit (402), which is matched to the cyclic 'signal and filters out transitory irregularities in the periods of this signal. 41.) Device according to claim 40, characterized in that that the markings (51, 52) are synchronized with the point-by-point scanning of a light-sensitive material (6l) be scanned by at least one light beam, which is simultaneously modulated by a variable signal in order to the material a number of tonal value » to expose details, and that the periodic cyclic signal establishes such a synchronous relationship between the variable signal and the scanning of the material that the exposure of the Tone value details at certain points along the scanning path that the light beam describes on the material. 009832/0775 JWtäÜ -'- ' ^;; - " ⁿ BAD ORIGINAL 42.) Device according to claim 41 or 42, characterized in that that the periodic cyclic signal through the tuned circuit arrangement (402) into a sinusoidal Output oscillation is transformed so that the output , Oscillation is clipped, so that the periodic cyclic ! Signal is given a shape that crosses a certain signal level indicated by the output oscillation, but independent of ι Changes in the amplitude of the output oscillation with respect to this Pej gels is. '43. ) Light lock with two electrically conductive strips which transversely enforce a magnetic field and run across the path of a light beam within this field, characterized in that the strips each contain two interconnected metal strips, the first of which has a higher tensile strength than the second and the second have a greater electrical conductivity than the first. 44.) Device according to claim 2 and 4 and one of claims 5 to 36, characterized in that the Transverse component of the displacement corresponding to a component perceived when the original is scanned, which is the direction of the contour of the gradient and runs transversely to the scanning direction in the original, is generated. 45.) Device according to claim 44, characterized in that that at least one image signal is generated from the tone values scanned in the original, that the reproduction of scanned tonal values of the original on the recording medium is controlled so that a sharpness-increasing signal is generated from the image signal, the differentiated image signal corresponds, and that the sharpness increasing signal is combined with the image signal in order to change this signal in such a way that that during playback on the recording medium, a gradient that was scanned in the original is displayed more sharply and has a contour direction having a component parallel to the direction of advancement of the scan · des Originals runs. 009832/0775 _BAD