Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
  • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
  • G01D5/34707—Scales; Discs, e.g. fixation, fabrication, compensation
  • G01D5/34715—Scale reading or illumination devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
  • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
  • G01D5/3473—Circular or rotary encoders

Definitions

• the invention relates to an optical angular position detector (also referred to as "position detector” for short) for determining the angular position of a rotary element, as used in galvanometer drives, for example.
• optical angular position detector also referred to as "position detector” for short
• Such scanning devices are used, for example, in the field of additive manufacturing processes where a laser beam is directed to selected locations of a layer of building material to selectively solidify the building material Ablenkspiegel mounted on a rotatably mounted shaft, whereby the impact of the deflected laser beam can be influenced by turning the mirror
• the rotational position of the mirror must be adjusted as accurately as possible and iffi g must be checked.
• a check of the angular position is usually done with a position detector, which determines the angular position.
• a position detector which determines the angular position.
• For a high measuring accuracy of such a detector a good temperature stability, a high signal-to-noise ratio and a good reproducibility of the output values are required.
• With regard to the operating speed it is necessary that the addition of the sensor, the moving mass is not significantly increased during rotation. In view of the handling also a small size of such a detector is advantageous. Since mainly capacitive position detectors have been used in the past, there has recently been a trend toward optical position detectors, since they tend to be cheaper and smaller in size.
• the optical position detectors there are initially those in which light from a light source penetrates a disk with opaque lines on its way to a detector arrangement, the disk rotating about the axis of rotation of the shaft whose angular position is to be determined.
• the angle information is coded on the barcode on the disc.
• the angular position is determined by counting the pulses which are caused by a light / dark transition caused by the movement of the bar code (incremental value transmitter).
• the absolute angular position can be encoded by the code on the disk (absolute encoder).
• This application is in contrast directed to such optical position detectors, in which the angular position is determined without the aid of a code (uncoded) from the analog output signal of the detector arrangement.
• the general operating principle of such an optical detector is that it allows light to fall on a sensor, wherein depending on the angular position of a wave different areas of the sensor surface are covered. Thereby, a correlation is obtained between the signal output from the photosensor area which is proportional to the area to which light is incident and the angular position of the rotating shaft.
• An example of such a sensor is described in European patent EP 1 071 929 B1.
• EP 1 071 929 B1 which is described with reference to FIGS.
• a rotary shaft 114 is housed in a housing 116 and rotatably supported there by means of bearings 118 and 120.
• a rotating mirror is attached to one end 125 of the shaft 114.
• the position detector 112. consists of a detector housing 121 in which photosensors 134, 136, 138 and 140, a light blocking element 130 and an LED light source 146 are housed. While the LED light source 146 and the photosensors 134, 136, 138, 140 are fixed, the light blocking member 130 is connected to the rotation shaft 114.
• the circular-segment-shaped photosensors 134, 136, 138, 140 are arranged symmetrically around the rotary shaft.
• the light-blocking element 130 has the shape of a tie loop (usually referred to as a "butterfly") and covers different sections of the photosensors depending on its angular position.
• the measurement accuracy of such a position detector is affected by radial and axial movements of the shaft.
• EP 1 071 929 B1 uses a wide-angle LED which is arranged as close as possible to the photosensors, so that as much light from the light source as possible is applied to the light source without further intervening optical elements Photo sensors can come up.
• Such a construction also has the further advantage that it is very compact.
• the photosensor readout sums up the signals of two photosensors lying opposite one another and supplies the two sum signals thus obtained to the different inputs of a differential amplifier.
• a basic prerequisite for the above-described position detector of the prior art is the presence of a wide-angle LED, which radiates as homogeneously as possible in all angular directions.
• a disadvantage of the embodiment just described is that in order to utilize light rays emitted by the LED 41 at a particularly large angle, the diameter of the lens 42 must be quite large.
• parallel light passes from the lens 42 to the sensors 44, not all of the parallel light is needed because the sensors 44 take only a fraction of the surface of the board 46.
• FIG. 1 shows a schematic lateral cross section through an angular position detector according to the invention.
• Fig. 2 shows a plan view of that portion of the angular position detector shown in Fig. 1, in which the detector element and the light blocking element are located.
• 3 shows the beam path in an angular position detector according to a first embodiment.
• FIG 4 shows the beam path in an angular position detector according to a second embodiment.
• FIGS. 5 and 6 show prior art position detectors according to EP 1 071 929 B1 in a side sectional view and in a plan view of the photosensors used in the position detector.
• Fig. 7 shows a prior art position detector according to US 7,688,432 Bl.
• Figs. 1 shows a lateral cross section through the position detector according to the invention, which is shown only schematically.
• Fig. 2 shows a plan view of the detector section with the photosensors and the light blocking element, and Figs. 3 and 4 show the optical paths of the light emitted from the light source using the structure shown in Fig. 1.
• a section line Sl-Sl is shown, which is intended to indicate the position of the cross-sectional plane in Fig. 1.
• the present invention is directed to a position detector in which the angular position is determined without the aid of a code (uncoded) from the analog output signal of the detector arrangement.
• a printed circuit board 9 photosensors 18, 19, 20 and 21, a diaphragm mask 10 and a light blocking element 5 are arranged one above the other.
• the photosensors 19, 20 are shown only for better understanding. Strictly speaking, no photosensor would be visible along the section line shown in FIG. Not shown in Figure 1 is still a surrounding the overall structure in Fig. 1 housing, which terminates the construction light-tight relative to the environment.
• FIG. 1 Analogous to the construction of FIG. 5, the construction shown in FIG. 1 is connected to a rotary shaft, to which, for example, a galvanometer mirror can be fastened.
• the rotary shaft is arranged below the structure in Fig. 1 so that its longitudinal axis, which is also the axis of rotation A, in the vertical direction passes centrally through the fastening screw 12 therethrough.
• the fixing screw 12 By means of the fixing screw 12 while the light blocking element 5 is fixed to the rotary shaft so that it can rotate with the rotary shaft, while the printed circuit board 9, the photosensors 18, 19, 20 and 21 and the diaphragm mask 10 are stationary.
• the light blocking element 5 which is a loop-shaped loop in the same way as in the prior art (Butterfly) element is positioned so that its axis of symmetry coincides with the longitudinal axis A of the shaft.
• the diaphragm mask 10 partially covers the photosensors 18, 19, 20, 21 and has an annular segment-shaped recess above each of the photosensors.
• An annular segment-shaped recess is advantageous because this results in a uniform shading of the photosensors 18, 19, 20, 21 with a rotation of the tie loop-shaped (butterfly) element results, resulting in a very good linearity.
• the outer edge of the light blocking element 5 has a greater distance from the longitudinal axis A of the rotary shaft than the outer edge of a circular ring segment.
• the light-blocking element 5 in the context of the invention may well have a different shape than the "butterfly" shape.
• the light-blocking element 5 has symmetrically arranged covering regions to its axis of symmetry coincident with the axis of rotation, which are delimited in the circumferential direction by straight lines passing through the symmetry axis, so that straight edges are present at these points.
• the shape of the light-blocking element 5 has, in particular, an n-fold symmetry (n 2).
• the recesses in the aperture mask 10 may also have a different shape.
• photosensors are not necessarily used, but may be two, three, five, six, seven, eight or more photosensors which are also disposed about the rotation axis such that the rotation axis does not pass through any of the photosensors.
• the photosensors are usually arranged symmetrically about the axis of rotation around, ie, the photosensor array has in a plane perpendicular to the axis of rotation n-counted symmetry (n 2).
• n 2 a symmetrical Arrangement to a mirror plane (in which the axis of rotation is located) possible.
• the signals of two photosensors lying opposite one another are summed up analogously to the procedure described in EP 1 071 929 Bl for photosensor readout and the two sum signals thus obtained are added to the different inputs fed to a differential amplifier.
• the evaluation of the signals of the photosensors can also be carried out in a different manner as an alternative to the procedure described above.
• a single light source 3 can be used in the present case.
• This may be a commercially available LED or laser diode. LEDs or else laser diodes which can be used for the present invention may already contain lenses or aperture elements.
• the light source 3 is shown only schematically, the beam path is shown as if all the rays emanate from a point.
• FIG. 1 additionally shows a holder 11, for example a printed circuit board, on which the light source 3 is mounted.
• the basic idea of the present invention is that the better the utilization of the light emitted by the light source 3, the greater the signal delivered by the detector. Ideally, if possible, the entire light emitted by the light source 3 should fall on the photosensors, if one disregards a cover by the light blocking element 5.
• the light emitted by the light source 3 is therefore directed into an annular region on the printed circuit board 9 with the photosensors 18, 19, 20 and 21, in which the annular segment-shaped Photosensors or circular segment-shaped openings in the aperture mask 10 are. Since this objective can not be achieved with a lens as in FIG. 7, it is the idea of the invention to use a beam-shaping element or beam-shaping element designated by reference numeral 7 in FIG. in the
• this beam-shaping element 7 is also referred to as free-form element, since the desired beam shaping is achieved in that the beam-forming element 7 has at least one non-planar, non-spherical surface, are reflected at the light rays from the light source in the beam-forming element 7 on their way to the photosensors ,
• the beam-shaping element 7 in Fig. 1 has a frusto-conical shape, wherein the axis of symmetry of the truncated cone passes through the center of the fastening screw 12 and, when the position detector is attached to a rotary shaft coincides with the axis of rotation A.
• a truncated cone-shaped recess 4 is present at the light source 3 facing back 30 of the beam-forming element 7 .
• the fixing screw 12 facing side 32 of the beam-shaping element 7 has a central region 32 a, which is substantially parallel to the plane of the photosensors, and an edge region 32 b. Since the central portion 32a is set back more than the edge portion 32b with respect to the fixing screw 12, the surface 32b corresponds to the side surface of a truncated cone.
• the side surface 6 of the beam-shaping element 7 has a convex shape. As can be seen in FIG. 1, the side surface 6 can be arched in particular outward relative to the axis of symmetry and be a free-form surface.
• the precise shaping (curvature) of the individual surfaces of the beam-shaping element 7 can be determined by simulation calculations using commercially available software, for example ASAP. the.
• the free-flying surfaces can be described for example by polynomials, splines or in another way. Since the side surface 6 may be curved outwards, the shape of the beam-shaping element 7 has been deliberately described above as "frusto-conical".
• a frusto-conical shape in which the side surface is not curved outward in the sectional view of Fig. 1, is a special case thereof. Since the lateral surface 4b of the recess 4 in the sectional view of Fig. 1 may also have a curvature, the shape of the recess 4 has been generally characterized with "frustoconical".
• the beam-shaping element 7 made of a plastic material (for example Plexiglas) or e.g. can be made of glass, characterized in that the light is directed not only by refraction, but also by reflection in the beam-shaping element on the photosensors.
• a reflection takes place on a boundary surface of the beam-shaping element 7 to the outside, namely a reflection on the side surface 6.
• this is a total reflection, in which more than 99% of the light is reflected in order to have the highest possible light output.
• one can also work without total reflection e.g. by coating the side surface 6 with a metal. The mere fact that one uses the reflected light on the side surface 6, already leads to an improvement over the case shown in Fig. 7.
• the invention brings an improvement over the prior art.
• the improvement is greatest when as little light as possible is lost.
• the position detector according to the invention also has a compact, space-saving design.
• FIG. 3 shows the beam path when using a beam-shaping element 7 according to a first embodiment.
• the arrangement of the light source and the beam-shaping element 7 are identical to the arrangement in Fig. 1.
• the structure below the beam-shaping element 7 is identical in Fig. 3 to the structure in Fig. 1.
• a plane 23 is shown schematically in FIG. 3, which is intended to represent a plane in which the planar sensors 18, 19, 20, 21 are arranged.
• the position of the photosensors 19, 20 is shown only schematically.
• the light source 3 is arranged close to the side of the beam-shaping element 7 facing away from the photosensors, so that it does not protrude into the recess 4.
• the rays emanating from the light source 3 are first refracted at the edge of the recess 4 in the beam-forming element 7 and subsequently directed by total reflection on the side surface 6 of the beam-shaping element 7 in the direction of the photosensors 19 and 20, wherein a refraction occurs again on the exit side 32.
• the exit-side surface 32 is not divided into two parts as in FIG. 1, but essentially flat.
• the light rays from the light source 3 end at the edge of the recess 4 in the forward direction (at a certain angle around the axis of symmetry when the direction on the axis of symmetry to the photosensors is assumed to be 0 °). This is because at this point the edge of the recess 4 is coated with an opaque material. This prevents light from falling onto the fastening screw 12 and being reflected by it in an uncontrolled manner.
• the surface of the frusto-conical recess 4 facing the photosensors that is to say the bottom 4a of the recess 4, is opaque to light.
• the opacity can be accomplished by applying black paint (eg, based on carbon black) as an opaque layer.
• black paint e.g. based on carbon black
• an opaque disc e.g. a black anodized aluminum disc may be glued or otherwise attached to the bottom 4 of the recess.
• the light is focused only on a portion of the photosensors.
• the "light spot” has the shape of a circular ring, the width of which is significantly smaller than the width of the annular segment-shaped photo sensors 18, 19, 20, 21 or annular segment-shaped openings in the diaphragm mask 10.
• the reflection of the light on the side surface 6 is thereby a redistribution of the light of the light source causes light that is emitted at small angles in the forward direction (the direction in which the axis A is assumed in FIG. 1 is assumed to be in the 0 ° direction) enters the outer part of the light source Annular ring and light, which is emitted from the light source 3 at undersized emission angles, enters the inner part of the annular region.
• the beam-shaping element 7 ensures that the largest possible proportion of the light emitted by the light source 3 hits the photosensors. Although a certain angular range of the forwardly radiated light of the light source 3 due to the opaque coating on the
• Beam shaping element 7 is not used for the illumination of the photosensors, very good signal / noise values were achieved for the position detector according to the invention. This is u. a. that the solid angle part of the light at large emission angles (when the forward emission direction is given as 0 °)
• Solid angle is meant that portion of a spherical surface surrounding the light source 3, which is penetrated by the light rays emitted by the light source 3, it being assumed that the light source is a point-shaped radiator.
• a high percentage of the total angular space of the area in which the light source 3 radiates is used. This leads to an improved utilization of the light from the light source 3 even taking into account the fact that the radiation density of the light source at large radiation angles is usually less than at small radiation angles.
• the angle 14 shown in Fig. 3 at the bottom of the recess 4 is slightly larger than 90 °.
• the angle can be between 90 ° and 105 °, preferably between 91 ° and 95 °.
• the inclination of the side walls of the recess 4 influences the refractive behavior. The closer the angle is to 90 °, the further outward the rays are refracted. This results in the result that the beam-shaping element 7 can be configured correspondingly shorter. For angles near 90 °, therefore, a particularly compact construction is achieved.
• the angle should, however, preferably be slightly greater than 90 °, since this results in advantages in the production of the beam-shaping element 7. Since the beam-shaping element 7 is preferably produced by means of injection molding, an angle of more than 90 ° facilitates removal of the injection-molding tool from the recess 4.
• the beam-shaping element 7 is held, ie in its position between the light source 3 and the structure consisting of the fastening screw 12, the light blocking element 5 and the photosensors 18, 19, 20, 21 is fixed.
• the beam-shaping element 7 it is advisable to fix the beam-shaping element 7 on a housing, not shown in the figures, which surrounds the overall construction shown in each case. Since the beam-shaping element 7 is preferably produced by means of injection molding, it is also advisable to form the support elements integrally with the beam-shaping element 7 by injection molding. One might think, for example, of noses, webs or snap hooks as holding devices.
• the holding elements that provide a positive connection with the housing.
• the holding elements are arranged on the side surface 6, they should preferably be arranged where there is no reflection of the incident light on the photosensors.
• a cylindrical housing is especially possible.
• the connection between the inner cylinder and the beam-shaping element 7 can take place by means of injection molded gleichsStege between beam-shaping element 7 and inner cylinder, so that ultimately the beam-shaping element 7, the connecting webs and the inner cylinder are formed as an integral part by injection molding.
• the holding elements can also be adhesively bonded to the beam-forming element 7, wherein, if the contact surface between the holding elements and the beam-forming element 7 is at a position where reflection of the light striking the photosensors takes place, a layer is preferably applied which can reflect light toward the interior of the beam-shaping element 7. In this way it is achieved that also the contact areas between the support elements and the beam-shaping element 7 can be used as reflective surfaces.
• Second embodiment 4 shows the beam path when using a beam-shaping element 207 according to a second embodiment.
• the second embodiment differs from the first embodiment only by the changed beam-shaping element 207. All other elements of the second embodiment are identical to the first embodiment. Furthermore, all the modifications described with respect to the first embodiment are also applicable to the second embodiment.
• the surface 232 of the beam-shaping element 207 facing the photosensors 19, 20 is not planar, but, as in FIG.
• the light beams emitted by the light source 3 do not penetrate the bottom of the frusto-conical recess 204. This is in turn because the bottom 204a of the recess 204 is coated with an opaque material. As in the case of the first embodiment, an opaque layer could of course alternatively be applied to the beam-shaping element 207 in the central region 232a of the exit surface 232.
• the light beams emitted by the light source 3 are first refracted at the edge (of the lateral surface 204b) of the recess 204 and subsequently directed by total reflection on the side surface 206 in the direction of the photosensors 18, 19, 20, 21, wherein another refraction takes place on the surface 232 ,
• the side surface 206 is in turn, as in the first embodiment, a free-form surface whose shape has been determined by simulations.
• the light of the light source 3 is concentrated on a circular ring whose width is greater than the width of the circular segment-shaped photosensors or the circular segment-shaped recesses in the diaphragm mask 10.
• the beam-shaping element 207 acts as a collimator the parallel light exits at the exit side 232 in the direction of the photosensors.
• the second embodiment has the following advantage:
• the light leaving the light source 3 is reshaped by the beam-shaping element 207 in such a way that it is in the form of a
• Annular ring in the direction of the plane 23 with the photosensors 18, 19, 20 and 21 radiates. Specifically, the presence of the recess 204 and the arrangement of the light source 3 immediately behind the side of the beam shaping element 207 facing away from the photosensors ensures that even under a large beam
• the light source 3 (the above-defined 0 ° direction) emitted light rays are directed by reflection in the direction of the photosensors. Since the light is reflected on the correspondingly shaped side surface 206 of the beam-shaping element 207 in the direction of the photosensors, more light from the light source 3 is directed to the photosensors than with a diaphragm of the same diameter. In contrast to a diaphragm, the light is not directed into an arbitrarily large area outside the area covered by the photosensors.
• the annular illumination area generated by the beam-shaping element 207 according to the second embodiment is, in contrast to the first embodiment, wider in the radial direction than the width of the nikringsegraentförmigen photosensors 18, 19, 20, 21 and the annular segment-shaped recesses in the aperture mask 10, however, the width of the annulus does not exceed the width of the circular ring segments or annular segment-shaped recesses to a significant extent. Unlike a shutter, this focuses the light more on the photosensors.
• the width of the annular illumination region is greater than the width of the circular ring segments or annular segment-shaped recesses, there is also insensitivity to radial displacements of the photosensors with respect to the light source 3.
• the width of the circular ring region can be adjusted via the shaping of the side surfaces 206 and thus the reflection behavior of the side surfaces 206.
• the invention is not limited to the explicit embodiment of the two embodiments just described. Rather, the following modifications are possible in both embodiments:
• the exit surface 32 or 232 need not be planar. Rather, this surface may have a curvature, depressions or steps. For example, a recess may be provided which allows a dipping of the fastening screw 12. As a result, a very small distance between the beam-shaping element and the photosensors 18, 19, 20, 21 together with the light-blocking element 5 can be achieved, such a measure is advantageous in terms of a compact construction.
• the exit surface 32 or 232 can also be a free-form surface of any desired shape.
• Their exact design which can be determined by means of simulations (for example by ASAP), then depends on which type of "light spot" is to be generated, that is, which planar shape the light incident on the plane 23 with the photosensors should have.
• the bottom 4a, 204a of the recess 4 or 204 and / or the lateral surface 4b, 204b may be free-form surfaces.
• an opaque layer may alternatively or additionally be applied in the central region of the exit side 32 to the Strahlformungselernent 7, ie where the exit side 32 to the mounting screw 12 shows.
• the opaque layer can be realized in the same way as described for the first embodiment. It should be noted that it is also possible to completely dispense with the attachment of opaque layers to the beam-shaping element 7. In particular, in such a case, the rays should not impinge directly on the photosensors at small angles of radiation which end in the light-impermeable layer in FIGS. 3 and 4 at the bottom 4a and 204a of the recess 4 and 204, respectively.
• the head of the fastening screw 12 should continue to be blackened to prevent disturbing reflections on the screw head.
• the shape of the recess 4, 204 and / or the exit side 32, 232 such that the beams are at small angles of radiation, ie for angles smaller than + 30 ° or less ⁇ 25 °, targeted to the blackened head of the mounting screw 12 are directed.
• the screw head has a recess (for example, a hexagon socket), you can also direct the rays targeted in this recess. In this procedure, you can even do without blackening of the screw head, although a blackening in this case is beneficial.
• the recess 4 or 204 may have inwardly curved side walls 4b tapering at the bottom.
• the area in which the side walls 4b meet may be similar to the area around the lowest point of a common or shortened cycloid.
• the light source 3 can also dip into the recess. If the light source does not protrude into the recess 4 or 204, the distance between the light source and beam-shaping element should be so small that as far as possible all the rays of the light source (including those at large radiation angles) strike the beam-shaping element.
• the beam-shaping element has a rotationally symmetrical shape
• the surfaces 30 and 230 opposite the light source and / or the surfaces 32 and 232 opposite the photosensors are polygons.
• the beam-shaping element 7, 207 and / or the recess 4, 204 may have a pyra truncated-stump-like shape.
• the free-form surface in the beam-forming element, on which the light is reflected, does not necessarily have to be nikzylinderför mig.
• the light blocking element although the invention is not limited thereto, in the present invention in particular special with a diameter below 10 mm, preferably be formed between 2 and 9 mm.
• position detectors in which the angular position is coded come up against limits with increasing demands on the accuracy of the angle measurement. The reason is that in the coding position detectors which usually use a coding disc, the angular resolution can be obtained only by increasing the disc diameter, since the bar code on the disc can not be formed with arbitrary fineness.
• the moment of inertia with respect to the axis of rotation, it is so that with the present invention position detectors with a particularly low moment of inertia of the rotating about the axis of rotation element (here the light blocking element) can be realized.
• the moment of inertia of the element (here the light blocking element) rotating about the axis of rotation may be below 0.010 g-cm 2 , preferably below 0.008 g-cm 2, and more preferably below 0.006 g-cm 2 .
• even position detectors can be realized in which the moment of inertia of the rotating about the axis of rotation element (here the light blocking element) is between 0.003 and 0.004 g-cm 2 .
• the (angle) position detector according to the invention can be used in a scanning device mentioned in the introduction, by means of which a light beam, in particular a laser beam, is directed to different points of a surface in order to detect properties at these points or there To perform machining operation using the laser beam.
• the angular position of a rotating mirror used for the deflection of the light beam, which is attached to a connected to the light blocking element 5 axis of rotation A can then be determined and for the control of a scan can be used.
• the position detector according to the invention can be used in a scanning device, as described in EP 1 295 090 B1. Details of the use in a scanning device (an example of the mechanical attachment of a Winkelpositi onsdetektors in a scanning device) are already described in EP 1 295 090 Bl and therefore will not be repeated here.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Optical Transform (AREA)
• Optics & Photonics (AREA)

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• 2013
  • 2013-05-10 DE DE102013208649.0A patent/DE102013208649B4/de active Active
• 2014
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  • 2014-05-08 WO PCT/EP2014/059496 patent/WO2014180968A1/de active Application Filing
  • 2014-05-08 CN CN201480035258.3A patent/CN105324632B/zh active Active
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