DE3340947A1 - Optical grid output and/or grid input device - Google Patents

Abstract

In an optical grid output and/or grid input device, comprising a two-dimensional grid field (24) having light sources (30) and/or light sensors at the grid points (28), a mask (46) whose position is variable relative to the grid field (24), and a control circuit (60) for selectively switching the light sources on and off and for determining the locations of the light-receiving light sensors in each case as a function of the instantaneous relative position of the mask (46), it is proposed to construct the mask as a perforated mask having hole dimensions (P) which are small with respect to the light-emitting surface dimensions ( DELTA X, DELTA Y) of the individual light sources (30) and/or with respect to the light capture area dimensions of the individual light sensors, the arrangement of the holes (50) and the movement path of the mask (46) being defined in such a manner that the holes (50) scan the individual areas (42). <IMAGE>

Description

Optical raster output and / or raster input device

The invention relates to an optical raster output and / or raster input device according to the preamble of claim 1 (opto-electronic output and / or input unit).

From DE-OS 27 39 158 an optical raster output device is known of this type. It is used to represent alphanumeric characters with an infinite Resolution, including the mask for each output line with a complete set of Output characters are provided, which are next to each other in a horizontal row at the height of the line are arranged.

To represent a specific character in this line in a The light source currently in this position becomes the predetermined column position of the grid momentarily switched on for the moment in which the desired Character of the mask is moved past this light source. This known raster output device can be used as a flat screen data display device, with only the accuracy of the Training of the characters of the mask dependent Resolution. The application However, this known device is limited to the representation of predetermined ones Sign; It is also possible to enter information in a grid by means of an input pen (e.g. Light pen) not possible.

The object of the invention is to provide a flat-building device of the type mentioned at the outset, with the possibility of entering and / or Output of any characters, especially drawing lines, with higher precision than the grid size.

This task is achieved by the features of the characterizing part of the claim 1 solved in connection with the features of the preamble. With the optical output is then, when a hole in the shadow mask is currently in the desired position, briefly illuminates the corresponding underlying light source. Accordingly, when entering the location coordinates of an image point using Input pen then generates a detection signal when the corresponding hole exactly between input pen and light sensor (for input pen with light source) or between input pen and light source (for input pen with light detector) is located; the control circuit then forwards from the current t-mask position to Time of generation of the detection signal the exact position of the mask hole above of the light detector or the light sensor. The device is flat, as the # light source grid (in contrast to a cathode ray tube, for example) only relatively low height and the mask arranged above and parallel to the grid field also does not require a lot of height. The imaging accuracy is determined by the hole dimensions and is therefore much larger than the imaging accuracy speed of the light source grid field without a shadow mask according to the invention. Through appropriate Control of the light source grid field by the control circuit can be any Reproduce (and enter) figures, especially drawing lines.

From DE-OS 23 46 208 a digital time display device is known, in which between a single light source (fluorescent tube 20 with a hollow cylinder reflector 22 and a perforated mask 24) a further perforated mask 34 is arranged, which step by step can be moved on a circular path in the mask plane to generate digital digits. The digital digits are made up of points, whereby the points are distinguished by momentary Match the position of holes in both masks. This arrangement too is limited to the representation of given characters.

DE-OS 23 09 604 discloses an optical raster output and / or raster input device is known in which the light source grid as a whole is so mechanically, e.g. is movable on a circular path that the movement paths of adjacent raster light sources cut.

The intersection points form the actual grid points of the grid field; by making these neighboring light sources differently colored and the Light sources only shine at the point of intersection, a multi-colored one can be used Achieve representation; by passing one of the neighboring light sources through a Replaced light sensor, the known device can also be used as a grid input device use. Finally, you can let the light sources light up several times of the grid field during a circular movement the imaging accuracy accordingly raise. However, there are limits to the improvement in accuracy for the movement of the relatively heavy light source grid is practically only that indicated Circular motion comes into question.

From DE-PS 29 25 613, finally, it is known for large-area Imaging of technical drawings with high accuracy, from a drawing machine, for example, computer-controlled to have a technical drawing made and this via an imaging system from behind on a viewing screen to project. This can with a sensor field for the input of information by means of Be provided with input pen. Another disadvantage of this arrangement is the limitation on the representation of drawn lines the high construction effort and the large space requirement, especially the great depth.

The development of the invention according to claim 2 ensures a uniform, Full-surface scanning of the light-emitting surface or light-trapping surface of the individual Light sources or light sensors.

To with a given repetition frequency of the flashing of a given The measure will be to reduce the rotational frequency of the belt at the point of the figure proposed according to claim 3.

A successive scanning of the surfaces by lying next to each other in the transverse direction Scanning surface strip is achieved by the measure according to claim 4. When there is overlap of the lines each become several areas of a column running in the transverse direction of the grid field scanned at the same time, which the scanning speed accordingly elevated. In the case of holes in alignment in the transverse direction, the control effort is simplified.

The measure according to claim 5 leads to a still picture.

To, if possible, with sufficient image brightness or input sensitivity To obtain high resolution, hole dimensions are proposed according to claim 6.

In order to achieve uniform illumination or To maintain the light sensitivity of the grid over the entire grid area, the measures according to claim 7 are provided. To realize the hollows with simple means, the grid according to claim 6 is proposed.

To enable the output image to be viewed from the side, is a transparent cover plate with light diffuser layer according to claim 9 suggested.

The fade-out optics proposed in claim 10 (realized for example through a diaphragm system in the input pen) ensures that the possible spatial resolution when entering signals is essentially as good as the accuracy a possible issue.

With input pen designed with a light source and the corresponding Light sensors in the grid field are used to localize the input pen that is placed on the grid nearest light sensor easily by appropriate design of the control circuit possible. On the other hand, if you want a grid field equipped exclusively with light sources identify the light source closest to the stylus using simple means, the induction arrangement according to claim 11 is proposed for this purpose. An advantage this arrangement is that when entering information, a The end- image can remain visible.

In order to be able to input location information, for example drawing lines through the input pen, a display of this location information is displayed immediately Achieve two alternative embodiments according to claims 12 and 13 suggested.

With CAD systems (computer aided design), the screen content can be printed out as a copy using a thermal printer. Such thermal prints are but not to scale. True-to-scale drawings, especially larger ones, have so far been produced using automatic drawing machines (plotters), with corresponding great structural effort. From DE-PS 29 25 613 it is known to the computer to provide connected automatic drawing machine with a light drawing head and to use a photosensitive drawing carrier.

Here, the light signal device can work with different Wavelengths be formed, a first wavelength of which the drawing and a second wavelength is used for erasing.

In order to use the above-described raster output optical device immediately obtain true-to-scale high-resolution drawing sheets the measures according to claim 14 proposed. In the preferred embodiment with the possibility of switching from a normal light intensity of the light sources to an increased light intensity, there is the possibility of using the drawing carrier while working on the device, for example with output of different Drawings or input of new drawings, to leave, and then only interesting ones Drawings or drawing details by switching to increased light intensity to be recorded on the drawing carrier.

Instead of different light intensities, different Light wavelengths are used according to claim 15 with correspondingly different Responsiveness of the drawing carrier.

According to claim 16, the cover plate of the device according to the invention be designed as a drawing pad for a manual drawing machine. The designer, which is computer-aided (CAD) design, can thus directly a stored, if necessary, construction drawing created by the computer and reproduced by the device Compare with a draft created manually on the drawing machine. Accordingly he can enter the design directly into the computer using an input pen.

The invention is illustrated below in terms of preferred exemplary embodiments explained with reference to the drawing.

It shows: Fig. 1 a. simplified perspective representation, partly in section, the device according to the invention; Fig. 2 shows the detail A in Fig. 1 in on an enlarged scale; and FIG. 3 shows a detailed section corresponding to FIG Input pen and FIG. 4 shows a detailed section similar to FIG. 2 of a modified one Embodiment.

The one described below with reference to the figure, generally designated 10 Device is used both for the large-scale reproduction of a computer-stored Image, as well as the storage (digitization) of location information (e.g. of construction drawings) corresponding actuation of a brought to the respective place input pen 12. However, the device can in accordance with the requirements of use, also exclusively for the reproduction of image information or to digitize image information. The device 10 requires a comparatively small installation depth and can therefore be used as a flat screen are designated. This enables the device 10 to be installed directly in a drawing machine for manual construction drafting, the device 10 takes the place of the drawing underlay (drawing board).

This makes computer-aided design (CAD) essential facilitated, as both the graphic computer output and the immediate one Location information input into the computer using an input pen (digitization) is going on directly on the drawing board. The designer can do this to scale Compare computer image with his own manually created draft and make corrections enter it directly into the calculator. The user of such a system is therefore in able to do his usual manual work on the drawing machine directly with computer support perform.

The basic structure of the device 10 is shown in FIGS. 1-3 emerged. One recognizes a base plate 14 with a side edge 16 running all around translucent cover plate 18 of the same size as the base plate 14 is placed on the edge 16 to form a closed interior 20 between panels 14 and 18 and rim 16. Panels 14 and 18 are rectangular Outline.

In the interior space 20 there is one parallel to the plates 14 and 18 Grid plate 22 on its top side facing the cover plate 18 has a line grid 24 is attached. On the one hand, the grid24 consists of one Dimension direction (X) of the plate 22 extending, distributed at a distance over the plate top 26 Lines 24a and running in the transverse direction (Y) to this, also with the same Distance over the plate top 26 distributed lines 24b. The lines 24a and 24b thus form a grid field with grid points at which the lines are located Cross 24a and 24b. Light sources 30 (see Sect. Fig. 2), in particular in the form of light emitting diodes, arranged. The light sources 30 then emit light when through the associated grid point 28 through appropriate Wiring of the lines 24a and 24b which meet here, current flows.

According to FIG. 2, the light sources 30 are slightly above the top of the plate 26 emerges. As a result, they protrude upwards (towards the cover plate 18) which are widening Wells 34 into it. These troughs are formed from the spaces between a grid 36 formed at right angles intersecting prism bars 38a and 38b. Like Fig. 1 1 and 2, the prism poles 38a extend between adjacent lines 24a and accordingly the prism poles 38b between adjacent lines 24b. in the In cross-section, the prism poles are each triangular, with the triangular base runs parallel to the plate top 26 and rests against it and the triangle tip to the cover plate 18 indicates. Each trough 34 is accordingly four upwards from one another striving away prism surfaces of the grating 36 limited. The prism edges 40a of the Prism rods 38a and the edges 40b of the prism rods 38b in each case on the upper side of the grid 36 thus form the boundaries between adjacent troughs 34 and each define the trough opening area 42 of a trough 34. This trough opening area is equal to the effective light-emitting area in this trough 34 located Light source 30. In FIG. 1, an oblique hatching is used to select an arbitrary one Light-emitting surface 42 'marked.

To increase the amount of light passing through the surface 42 are the Prism side surfaces 44 as shown in FIG. 2 are mirrored.

The dimensions EX of a surface 42 in the X direction is about 10 mm, the dimension AY in the Y direction is approximately 10 mm. So the entire grid becomes practically seamless (except for the thickness of the edges 40a and 40b) in individual surfaces 42 divided, which by appropriate control of the light sources 30 optionally can be illuminated.

The dimensions of the grid field correspond in particular to the dimensions a drawing pad of a drawing machine.

The plate 22 as well as the grid 36 lying flat on it are wrapped around by a shadow mask tape 44. The belt 44 is in each case over a pulley 46 is guided at the two ends of the plate 22 spaced apart from one another in the X direction. The partial representation in FIG. 1 is accordingly mirror-symmetrical to the left to add a mirror plane perpendicular to the X direction. An upper run 46 of the Belt 44 runs in Fig. 1 from left to right in the direction of arrow v along the top grille 36; accordingly, a lower run runs parallel to this 48 of the band 44 on the underside of the plate 22 in Fig. 1 to the left. One of the two pulleys, for example the pulley 46 shown in Fig. 1, is driven by a motor 48 with constant angular velocity X.

The band 44 is provided with a multiplicity of holes 50 see, which are parallel to each other, at an angle to the relative direction of movement v (i.e. in X-direction) running lines 52 are arranged. The inclination of the lines 52 results from the offset Tx of adjacent holes 50 in the X direction and the offset Ty of the holes in the transverse direction (Y-direction). With a hole diameter P of the particular circular holes 50: Tx = AX + P and Ty = P.

Any depression 34 is located above surface 42 one and only one hole 50. Furthermore, in the course of the tape movement, a strip-wise one results Scanning the respective surface 42 through the successive holes 50, wherein the strips have a width corresponding to P and without overlapping in the Y direction close together. P is best about 0.2 mm.

In Fig. 2 are emitted from a light source 30 and from the prism sides 44 reflected light rays indicated by small arrows. You can see that just above this trough 34 located hole 50 as a pinhole for the rays works. This arrangement results in a bundling of rays upwards (direction Z), which is an observation of the subsequently through the translucent cover plate 18 falling light rays from the side. The underside 56 the cover plate 18 is therefore light-scattering, in particular through appropriate roughening educated. This is indicated by corresponding light arrows in FIG. 2.

For the optical output and input of data of a not shown Computer, this is with a tax circuit 60 of the device 10 connected, which is indicated in Fig. 1 as a block. The control circuit 60 is via a data and control line 62 for information transmission in both Directions connected to the computer. To control the individual light sources 30 individually Both the lines 24a are indicated via a corresponding one in FIG. 1 Collective line 64 as well as lines 24b via a further collecting line 66 the control circuit 60 is connected. The control circuit controls via a line 68 60 the motor 48. To determine the exact current position of the belt 44 in each case to be able to, the control circuit 60 is via a line 70 with a transducer 72 connected, which is attached to the edge 16 and a measuring track 74 of the tape 44 for example optically scanned.

However, it can also be used instead of or in addition to the transducer 42 use an angle encoder which is connected to one of the two deflection rollers 46 is. Finally, a stepper motor can also be used for the motor 48, at which from the outset the respective angular position of the motor shaft of the control circuit is known.

Around a luminous point approximately the size of the holes 50 at any point of the cover plate 18 (more precisely the roughening 58 of the cover plate 18), that light source 30 is made to glow by the control circuit 60, within which the light-emitting surface 42 lies the desired light point position. the Control circuit 60 briefly closes this light source 30 precisely at that moment Shine in which that hole 50 is with the Y coordinate of the luminous point corresponding Y-coordinate is currently in the desired position X. To a To produce an essentially flicker-free image, the belt 44 is like Speed v moves that the holes 50 with the same transverse position X with a frequency just exceeding the frequency of fusion of the human eye drive over one and the same surface 42.

The rows 52 of points 50 are arranged so closely on the belt 44 that so that there is a corresponding plurality of holes with the same transverse position with a corresponding reduction in the necessary running speed v of the belt 44.

In Fig. 2, a drawing carrier 80 (transparent drawing paper) is dashed shown, which can be placed on top of the cover plate 18. One in Computer-stored, possibly computer-generated construction drawing, can therefore by means of the device 10 according to the invention below the drawing carrier 80 mapped and, if necessary, with a drawing on the drawing carrier 80 directly be compared.

This is used to input location information using input pen 12 provided with a light sensor 82 and with a masking optics 84 to with one of the Hole diameter P substantially corresponding localization accuracy To be able to perform location information input. The masking optics 84 can, for example consist of a converging lens 86 at the lower open end of the input pen 12 and a perforated diaphragm 88 in the image plane of the upper run 46 of the belt (more precisely taken on the roughening 58) focused lens 86. Behind the hole of the pinhole 88 is the light sensor 82, which is essentially exclusively Receives light rays from the object plane in the area around the optical axis 90.

In order to align the input pen 12 with pinpoint accuracy one To enable drawing, this can be pointed downwards in a manner not shown run, for example in accordance with the further embodiment to be explained in more detail 112 of a light pen according to FIG. 4.

The light sensor 82 of the input pen 12 is via a line 92 connected to the control circuit 60.

In order to be able to determine above which of the light sources 30 the input pen 12 is currently located, one could think of all light sources 30 to be switched on in sequence under the control of the control circuit 60, so that the Time of occurrence of a detector signal on line 92 of a specific Light source 30 can be assigned. However, this requires the reproduction of optical information be interrupted by the device 10 at least briefly. To avoid this, is the stylus 12 with an induction coil symbolically shown in FIG 94 provided at its lower end, which when the input pen 12 acts on the plate 18 on the lines 24a and 24b immediately below and the possibility of localizing the corresponding grid point 28 by the Control circuit 60 creates. In Fig. 1 magnetic field lines 96 of the coil 94 are indicated; a power supply line 98 for the coil 94 is also indicated.

For direct input of the location coordinates of a point, for example of a drawing point, the input stylus only needs to be attached to the corresponding Be held in place (perpendicular to plate 18). The control circuit 60 thereupon sets due to the induction effect, the position of the assigned grid point is fixed and switches the associated light source 30. According to FIG. 3, there is a type of light barrier between the luminous light source 30 and the detector 82, which only then is open for a short time when that hole 50 with the same Y coordinate as the point to be entered currently has the same X coordinate as the point. Because of the constant determination of the position of the band 44 via the transducer 72 can from the control circuit 60 the moment of opening of the light barrier is exactly one specific hole 50 (Y-coordinate of the point to be entered) and assigned a current X position of this hole (X position of the point to be entered).

The light sources 30 can also have such a basic voltage are supplied that they are not made to glow at this basic voltage but by a slightly higher voltage, which is due to the induction effect can be generated locally by the induction coil 94.

In Fig. 4 is a second, designated 110 embodiment of the Device shown in section according to FIG. 3, with components, the components 1 - 3 correspond in their function, with the same reference numerals, respectively increased by the number 100. Different from the first embodiment here the troughs 134 are parabolic, so that an improved "headlight effect" compared to the prismatic embodiment according to FIGS. 1-3 results. Instead of Light sources 30 are provided here in the troughs 134, namely light sensors 130 in the respective focal point. The light sensors 130 are in turn at the intersection points of lines 124a and 124b switched on, corresponding to the arrangement in FIG. 1. the Wells 134 can again be made up of a continuous grid 136 be formed, which is supported flat on the plate 122. The perforated tape 144 is in turn provided with holes 150 corresponding to the arrangement in FIG. Above of the band 144 is the transparent cover plate .118, which, however, is preferably is formed without roughening. The device 110 is exclusively for entering a location educated. However, it is also a hybrid form between the embodiments 10 and 110 conceivable, that is to say both with light sources and with light sensors in the individual hollows.

The input pen 112 is now provided with a light source 182 (instead of of the light sensor 82), which is at the focal point of a converging lens 186 is located as part of a masking optics 184. From the resulting parallel rays a bundle of rays is masked out with a hole diameter P substantially corresponding bundle diameter. For this purpose, the input pen 112 is conical downwards tapered and with a correspondingly small opening at the cone tip Mistake.

To enter the location coordinates of a point, for example a Drawing line of a not shown, placed on the plate 118 technical Drawing, the input pen 112 is held on the plate 118 accordingly (perpendicular to plate 118). In turn, a light barrier is obtained between the light source 182 and the light sensor 130 located below the input pen 112. These The light barrier is only opened briefly when the hole is is in the correct X position with the correct Y coordinate.

The control circuit 60 can be controlled by the appropriate Signals flowing to lines 124a and 124b both the location of the determine momentarily illuminated light sensor 130, as well as from the time of When the corresponding signals occur, infer the current hole location.

To make true-to-scale copies (hard copy) of those reproduced by the device To obtain images, it is only necessary, instead of a conventional one Drawing carrier 80 according to FIG. 2, a drawing carrier with photosensitive Lay the layer on, the responsiveness being higher than the ambient brightness. You can also adjust the sensitivity so that it is only then there is a record when the light sources 30 to emit increased light intensity be controlled, which is above a normal imaging light intensity.

The photosensitive drawing carrier can therefore during the the usual CAD work on the flat screen. You can also go with different light waves work, whereby the drawing carrier is only for one of the two light wavelengths is responsive.

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Claims (18)

Optical raster output and / or raster input device Claims Optical raster output and / or raster input device comprising a two-dimensional one Grid field (24) with light sources (30) and / or light sensors (130) at the grid points (28), a mask variable in position relative to the grid field (24) between the grid field (24) and an observer or between the grid field (24) and an input pen (12) and a control circuit for optionally switching the light sources on and off (30) or to determine the locations of the light-receiving light sensors (130), respectively depending on the current relative position of the mask, thus g e k e n n z e i c h n e t that the mask is designed as a perforated mask (46). with hole dimensions (P) small compared to the. Light emission surface dimensions (# x, # Y) of the individual light sources (30) or compared to the light-trapping surface dimensions of the individual Light sensors (130), and that the arrangement of the holes (50) and the path of movement of the mask (46) is set in such a way that the holes (50) scan the individual surfaces (42), always only a single hole (50) sweeps over an area (42). 2. Device according to claim 1, with a relative to the grid field (24) linearly movable mask, possibly in the form of an endless belt (44), thereby g e k e n n -z e i c h n e t that in the direction of movement (X) of the mask successive Holes (50) in this direction a distance (Tx) from hole center to hole center of at least the same, preferably approximately the same as the corresponding surface dimension (AX) plus the hole dimension (P) in this direction and in the transverse direction (Y) a hole spacing (Ty) approximately equal to the hole dimension (P) in this direction. 3. Apparatus according to claim 2, characterized in that g e k e n n -z e i c h n e t that each hole (50) at least one further hole (50) with the same transverse position assigned. 4. Apparatus according to claim 3, characterized in that g e k e n n -z e i c h n e t that the holes (50) on mutually parallel, oblique to the relative direction of movement extending lines (52) are arranged, preferably with in the transverse direction (Y) in Aligned holes (50) of the rows (52) overlapping in the longitudinal direction (X). 5. Device according to one of the preceding claims, characterized in that g e k e n n n n e i c h n e t that the relative speed of movement (v) is set in such a way is that a hole (50) or the holes with the same transverse position with respect to the Relative direction of movement with a frequency at least the same the frequency of fusion of the human eye one and the same. Flat (42) run over. 6. Device according to one of the preceding claims, characterized in that g It is noted that the holes (50) have a diameter (P) of 0.1 bifi 1.0 mm, preferably 0.15 to 0.5 mm, most preferably about 0.2 mm. 7. Device according to one of the preceding claims, characterized in that g e k e n n n n e i c h n e t that the light sources (30) or light sensors in each case in directly adjoining, preferably internally mirrored receiving troughs (34) protrude, the trough opening surface being the light-emitting surface (42) or forms the light-collecting surface. 8. Apparatus according to claim 7, characterized in that g e k e n n -z z e i c h n e t that the troughs (34) have prismatic inner surfaces (44) and preferably are formed by a grid (36) of prism rods (38a, 38b). 9. Device according to one of the preceding claims, g e k e n n z e i c h n e t through a translucent cover plate (18) on the point grid (24) opposite side of the shadow mask (46), which is preferably with a Light diffuser layer (58) is formed. 10. Device according to one of the preceding claims, characterized in that g e k e n n n e i n e t that the one with a light source and / or a light sensor (82) provided input pen (12; 112) has a masking optics (84) which when connected to the device (10; 110) holding input pen (12; 112) the Light measurement of the radiation exclusively from a surface area of the shadow mask or the illumination exclusively of a surface area of the perforated mask (46) in each case with dimensions in the range of the hole dimensions (P). 11. Device according to one of the preceding claims, characterized in that g e k e n n n n e i c h n e t that the input pen (12) with a preferably of An induction arrangement (94) formed by an electromagnet is provided for control essentially exclusively the light source closest to the input pen (12) (30). 12. The device according to claim 11, characterized in that g e k e n n -z e i c h n e t that the control (60) to determine the location of the induction effect the induction arrangement (94) of the input pen (12) exposed grid point is designed as well as for the subsequent activation of the corresponding Light source (30). 13. The apparatus of claim 11, characterized in that g e k e n n -z e i c h n e t that the light sources (30) can be acted upon with a basic voltage, at which the light sources (30) do not yet shine, but by means of induction the induction arrangement of the input pen (12) is optionally brought to light up can be. 14. Device according to claims 9 to 13 g e -k e n n z e i c h n e t by a preferably translucent one that can be placed on the cover plate (18) Drawing carrier (80) with a light-sensitive layer, preferably with one Responsiveness, for an optionally adjustable increased Light intensity of the light sources above a normal light intensity of the light sources. 15. The device according to claim 14, characterized in that g e k e n n -z e i c h n e t that the light sources for emitting at least two different light waves> 'lenlängen are formed, and that the drawing carrier (80) only for one of the two Light wavelengths is sensitive to response. 16. Device according to one of claims 9 to 15, characterized g e k It is noted that the cover plate (18) serves as a drawing base for a Drawing machine is trained. 17. Device according to one of the preceding claims, characterized in that g It is not noted that the dimensions (EX, AY) of the light-emitting surfaces (42) respectively. of the light-trapping areas in the range between 1 and 20 mm, preferably 5 and 15 mm, preferably around 10 mm. 18. Device according to one of the preceding claims, g e k e n n z e i c h n e t by a measurement transducer scanning a measurement track (74) of the mask (72) and / or a stepper motor (48) for driving the movement of the mask.