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
  • G01D5/36—Forming the light into pulses
  • G01D5/366—Particular pulse shapes
• • 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
  • G01D5/12—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 using electric or magnetic means
  • G01D5/244—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 using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
  • G01D5/245—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 using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
  • G01D5/2454—Encoders incorporating incremental and absolute signals
  • G01D5/2455—Encoders incorporating incremental and absolute signals with incremental and absolute tracks on the same encoder
  • G01D5/2457—Incremental encoders having reference marks

Definitions

• the present invention relates to a scanning unit for an optical position measuring device.
• the position measuring device also supplies at least one reference pulse signal at a defined relative position of a scale and a scanning unit that is movable relative to the scale.
• at least one reference marking field is arranged on the scale integrated in the incremental graduation track.
• Known optical position measuring devices such as are used, for example, in machine tools for detecting the relative position of the workpiece and the tool, generally also supply so-called reference pulse signals in addition to incremental signals with respect to the relative set.
• reference pulse signals With one or more defined relative positions of the parts that are movable relative to one another, an exact absolute reference of the position measurement can be established using the reference pulse signals.
• reference marking fields are arranged at one or more positions on the scale of the respective position measuring device.
• the scanning unit of such a position measuring device offers the possibility of generating a corresponding reference pulse signal for the relative position of the scale and scanning unit to be detected, which reference pulse signal is suitably processed in the downstream evaluation device.
• scanning units In addition to generating the incremental signals with a scanning unit, which in addition to the corresponding detector elements also contains a scanning plate, scanning units are also known which have a so-called structured detector arrangement. In this case, active detector areas are provided on the scanning side of a semiconductor substrate, which are arranged adjacent to one another in the measuring direction and each provide specific signal components of the scanning signals. In such scanning units, therefore, a single component takes on the combined function of scanning division and detector element.
• EP 518 620 A1 may be mentioned, for example.
• a structured detector arrangement is known from DE 195 12 258, which is used to generate a reference pulse signal.
• the arrangement of the reference markings is again provided laterally adjacent to the incremental division.
• the problems mentioned again arise when rotating the scale and scanning unit about an axis which is oriented perpendicular to the scale or scanning plane.
• the design of the detector arrangement proposed in this publication is not suitable for scanning a reference marking which is integrated directly into the incremental graduation track.
• the object of the present invention is therefore to provide a compact scanning unit for an optical position measuring device which, in addition to incremental signals, also supplies a reference pulse signal at at least one defined position when scanning a scale.
• the influence of errors on the generation of the reference pulse signal, resulting from the above-mentioned rotation of the scale and scanning unit, is to be minimized, as is the susceptibility to possible contamination of the scale.
• the phase position of the reference pulse signal should also be retained in the event of the scale being tilted about an axis in the scale plane with respect to the incremental signals.
• the inventive design of the detector arrangement in the scanning unit now ensures the desired insensitivity in the event of a possible rotation of the scale and scanning unit about an axis perpendicular to the measuring plane.
• the position of the generated reference pulse signal does not change with respect to the incremental signals even in such a case.
• an extremely compact scanning unit can be implemented.
• so-called single-field scanning can also be ensured.
• the quality of the different scanning signals is in each case evenly influenced by possible contamination.
• Another advantage of the solution according to the invention is that the phase relationship between the generated reference pulse signal and the incremental signals is retained even if the scale is tilted in the scale plane. This is because both the incremental signals and the reference pulse signal result from one sample point on the scale.
• the measures according to the invention can furthermore be implemented in a wide variety of optical position measuring devices. This includes both systems that provide collimation optics in the illumination beam path and position measuring devices with so-called divergent illumination, i.e. Systems in which no collimation optics are provided in the illumination beam path etc.
• linear or rotary position measuring devices can of course also be designed according to the invention, as can systems which are operated in incident light or in transmitted light.
• Figure 1 is a schematic representation of an optical system
• Position measuring device with a scale which is designed by an inventive
• Scanning unit is scanned
• Figure 2a is a schematic representation of a first
• FIG. 2b shows a representation of the phase-shifted incremental signals and of the reference pulse signal, which can be generated via a scanning unit according to FIG. 2a;
• FIG. 3a shows a representation of a second embodiment of the scanning unit according to the invention in FIG.
• FIG. 3b shows a representation of the phase-shifted incremental signals and of the reference pulse signal, which can be generated via a scanning unit according to FIG. 3a;
• FIG. 4a shows a third embodiment of the scanning unit according to the invention in connection with a scale scanned therewith;
• FIGS. 4b, 4c each show reference pulse signal components which are generated in the scanning unit according to FIG. 4a;
• FIG. 4d shows the resulting reference pulse signal which is generated with the scanning unit according to FIG. 4a and an associated trigger threshold
• FIG. 5 shows a fourth embodiment of the scanning unit according to the invention in connection with a scale scanned therewith;
• FIG. 6 shows a fifth embodiment of the scanning unit according to the invention.
• FIGS. 7a-7d each show a schematic illustration to explain further possible embodiments of the scanning unit according to the invention.
• FIG. 1 shows an optical position measuring device, which comprises a scanning unit 1 designed according to the invention.
• a scale 2 movable relative to the scanning unit 1 in the measuring direction x belongs to the position measuring device.
• the scanning signals generated by the scanning unit 1 during the relative shift relative to the scale 2 are fed to the indicated evaluation device 3, which further processes these signals in a known manner.
• Both at least one incremental signal and at least one reference pulse signal are generated as scanning signals.
• the relative position of Tool and workpiece determined in a numerically controlled machine tool.
• a known numerical machine tool control is accordingly used as the evaluation device 3, to which the position-dependent scanning signals of the position measuring device are fed.
• the scanning unit 1 comprises, on the one hand, a transmission-side part which, among other things, has a light source 4 including a collimator lens 5 arranged upstream of the light source 4.
• a detector arrangement 6 with different detector areas is provided in the part of the scanning unit 1 on the detector side, the construction of which is explained in detail below with reference to the other figures.
• the transmitting and detector-side part of the scanning unit 1 can be moved relative to the scale 2 in the measuring direction x.
• an incremental graduation 8 extending in the measuring direction x is arranged on a scale 2 in an incremental graduation track 9, the optical scanning of which provides incremental signals in a known manner during the relative movement, preferably a pair of incremental signals with a phase offset of 90 ° .
• the scale 2 has, in the track 9 with the incremental graduation 8, alternately arranged incremental graduation partial regions 8a, 8b with different optical properties; in the case of the transmitted light design, there are incremental graduation subregions 8a, 8b which are designed to be non-transmissive and transmissive for the light wavelength used.
• a reference marking field 7 can also be seen, which is integrated in the incremental graduation track 9 of the scale 2 and is used to produce a clear absolute reference at a specific relative position of the scale 2 and the scanning unit 1.
• An enlarged representation of the reference marking field 7 is shown in the lower part of FIG. 2a.
• reference marking field 7 there is an arrangement of reference marking sections 7.1 - 7.13 in the measuring direction x, which deviates from the strictly periodic or equidistant arrangement of the incremental division sections 8a, 8b in the rest of the incremental division track 9 of scale 2.
• FIG. 2a an arrangement of a total of 13 permeable and non-permeable reference marking sub-areas 7.1-7.13 in the reference marking field 7 was chosen, with the incremental division 8 having strictly periodically alternating permeable and impermeable incremental divisions to clearly distinguish the reference marking field 7
• Sub-areas 8a, 8b are now designed to be impermeable to certain reference marking sub-areas. This ultimately results in an aperiodic arrangement of reference marking sub-areas 7.1 - 7.13 with different optical properties.
• the four reference marking subregions 7.1, 7.5, 7.11 and 7.13 which are located at locations where a permeable subregion would actually be arranged for generating the incremental signal, are designed to be impermeable for this purpose.
• reference marking fields 7 at defined positions can also be integrated into the incremental graduation track 9 of the scale 1. These can be so-called distance-coded reference marking fields as well as equidistantly arranged reference marking fields etc.
• FIG. 2a shows in the upper part a view of the detector level of the detector arrangement 6 from FIG. 1 in connection with various signal processing components. Below this, the incremental graduation track 9 of the scale 1 with the reference marking field 7 and the incremental graduation 8 adjoining it on the left and right is shown in an enlarged form.
• a plurality of radiation-sensitive detector areas D100-D107 are provided in this exemplary embodiment of the scanning unit according to the invention for detecting the beam bundles coming from scale 2, each of these being rectangular in shape and arranged in the measuring direction x with their long sides adjacent to one another.
• the different detector areas D100-D107 each supply signal components which are used in the manner described below to generate phase-shifted incremental signals INC 0 , INCgg and to generate a reference pulse signal REF.
• the respective outer or delimiting detector areas D100, D101 as well as D106 and D107 of the detector arrangement 60 are used here to generate the reference pulse signal REF; These detector areas are therefore referred to below as reference pulse signal detector areas D100, D101, D106, D107.
• the Rela- The arrangement of the four incremental signal detector areas D102-D105 provided in this exemplary embodiment is provided in such a way that the incremental signal detector area D102 is a partial incremental signal with the phase position 0 °, D103 is a partial incremental signal with the phase position 180 °, and D104 is a part -Incremental signal with the phase angle 90 ° and D105 delivers a partial incremental signal with the phase angle 270 °.
• the relative arrangement of the reference pulse signal detector areas D100, D101, D106, D107 within the detector arrangement 60 takes place according to the invention depending on the selected structuring of the reference marking field 7 on the scale.
• the design of the reference marking field 7 was chosen such that, deviating from the periodic arrangement of permeable and impermeable subregions 7.1 - 7.13, 8 individual reference marking subregions 7.1, 7.5, 7.11 and 7.13 were made impermeable in the incremental division .
• the four reference pulse signal detector areas D100, D101, D106, D107 are now arranged in the detector arrangement 60.
• the intensity of the reference pulse signal REF results, which is used for the precise detection of the
• the outputs of all reference pulse signal detector areas D100, D101, D106, D107 are interconnected.
• the resulting signal is present at the first input of a further differential element DIF30.
• the phase-shifted output signals of all incremental signal detector areas D102-D105 are summed up with the aid of a summing element SUM to form a reference signal with a constant signal level.
• the resulting reference signal is fed to the second input of the difference-forming element DIF30. After the difference formation from the two signals present via the difference formation element DIF30, the desired reference pulse signal REF results.
• the amplifier element AMP shown in the example in FIG. 2a can be used in front of the difference forming element DIF30, the gain factor of which is selected accordingly.
• phase-shifted incremental signals INC 0 , INC 90 generated with such a detector arrangement 60 and the reference pulse signal REF at the reference position XRE are shown schematically in FIG. 2b.
• the drop in the intensity of the reference pulse signal REF at the reference position XREF is clearly recognizable here.
• the periodic signal component resulting from such an arrangement is also recognizable, which is modulated onto the reference pulse signal REF adjacent to the reference position XREF and can possibly impair the detection reliability. This periodic signal component is shown exaggerated in the illustration in FIG.
• the first variant of the scanning unit according to the invention explained in FIG. 2a could be simplified in a further embodiment in that only two reference pulse signal detector areas are provided, between which at least one incremental signal detector area is arranged. Due to an increased insensitivity to interference, it is advantageous to design the detector arrangement with a plurality of detector areas for the incremental signals and the reference pulse signal, as shown in FIG. 2a. In addition, further detector areas for obtaining incremental signals and reference pulse signal detector areas are advantageously to be provided on the left and right adjacent to the reference pulse signal detector areas. In this way, the scanning area and thus the sensitivity to contamination is increased. In particular, it is advantageous to choose the sum of all incremental signal detector areas larger than the sum of the reference pulse signal detector areas, since thus minimizing the influence of the reference marking field on the generated incremental signals.
• FIG. 3a shows a view of the detector level of the detector arrangement 6 from FIG. 1 in connection with various signal processing components.
• the incremental graduation track 9 of the scale 1 is shown in an enlarged form with the reference marking field 7 and the incremental graduation 8 adjoining it on the left and right.
• a so-called structured detector arrangement 6 is now provided on the detector side for detecting the beam bundles coming from scale 2.
• this consists of active, ie radiation-sensitive detector areas D1, D2, D3 D44, each of which has a narrow strip shape and is arranged periodically and adjacent to one another in the measuring direction x.
• a suitable semiconductor substrate is to be structured in such a way that a number of such radiation-sensitive detector regions D1-D44 result on the substrate.
• the various active detector areas D1-D44 each provide signal components which are used in the manner described below to generate phase-shifted incremental signals INC 0 , INC 90 and to generate a reference pulse signal REF.
• the active detector areas D1-D44 of the detector arrangement 6 each have a raster spacing r in the measuring direction x, which is smaller than the division period TP of the scanned incremental graduation 8 as defined in FIG. 3a.
• TP corresponds to the sum of the width of a permeable and the impermeable incremental division partial area 8a or 8b in the measuring direction x.
• r TP / 4 is selected, which corresponds to a phase shift of the signals of adjacent detector areas of 90 °.
• the length of the active detector areas D1-D44 perpendicular to the measuring direction x has to be optimized depending on the respective optical configuration.
• the relative arrangement of the active detector areas D1-D44 in the measuring direction x is consequently chosen in this embodiment such that active detector areas D1-D44 and inactive detector areas are arranged alternately within a division period TP.
• the distance d between adjacent active detector areas D1-D44 and thus the width of the inactive zones is consequently TP / 8 in this exemplary embodiment.
• a total of 44 active detector areas D1-D44 are distributed equidistantly over eleven division periods TP in eleven groups of four over the entire detector arrangement 6 in the measuring direction x.
• the arrangement of the active detector areas D1-D44 shown in the example in FIG. 3a has the consequence that the adjacent active detector areas of a group of four lying within a division period TP during the optical scanning of the incremental graduation 8 and of the reference marking field 7 four, each by 90 ° deliver phase-shifted scanning signals.
• the arrangement of the detector areas shown thus ensures a so-called “single-field scanning” of the scale, in which all signal components for generating the incremental signals and the reference pulse signal always originate only from one division period of the scanned scale.
• Such scanning is particularly important with regard to insensitivity to large areas Soiling of the scale is advantageous since the phase-shifted signal components which contribute to the generation of the scanning signals are all influenced equally.
• a suitable choice of the position and size of the detector areas could, for example, also implement a so-called quasi single-field scanning in the context of the present invention, in which the signal components used for signal acquisition originate from detector areas which span more than one Extend graduation period arranged in the measuring direction, with adjacent detector areas each supplying signal components with different phase positions.
• the width b of the detector areas is then to be selected b TP TP / 2
• different phase positions of the individual, adjacent detector regions result.
• Detector areas D13 - D16, D21 - D24, D33 - D40 The specific processing of the output signals of the reference pulse signal detector areas GR EF ⁇ will be discussed in more detail below.
• the remaining groups of four active detector areas are used to generate the phase-shifted incremental signals INC 0 and INCgo; these groups are referred to below as incremental signal detector areas G ) NCn .
• NCn are the first to from the left
• NCn are, with the exception of the edge-side, first and eleventh incremental signal detector areas the detector areas of the reference pulse signal detector areas.
• the spatial position of these reference pulse signal detector areas GR EF I - GREF4 in the detector arrangement 6 corresponds to the spatial one
• Position of two successive impervious reference marking sub-areas in the reference marking field 7 on the scale ie the position of the reference marking sub-areas 7.1 and 7.2, 7.4 and 7.5, 7.10 and 7.11 as well as 7.12 and 7.13.
• the spatial position of the generation of the reference pulse signal relied reference pulse signal detector regions GREF ⁇ w 'r thus d selected as a function of the spatial position of the periodic scale structure destructive opaque reference mark sections 7.2, 7.5, 7.11 and 7.13.
• used to generate the reference pulse signal REF - GR EF4 takes place in
• the case of the collimated illumination is therefore directly dependent on the structure of the reference marking field 7 on the scale.
• the aperiodic structure of the reference marking field 7 in the detector plane is thereby reproduced by the selected active detector areas of the reference pulse signal detector areas G REFn for the detection of the reference pulse signal REF.
• this exact reproduction of the structure of the reference marking field by the choice of the reference pulse signal detector areas G EF ⁇ used for the formation of the reference pulse signal is by no means mandatory for the present invention.
• ten divergent illumination of the scale without collimator optics may also be necessary to select active detector areas of the reference pulse signal detector areas G F ⁇ for reference pulse signal generation which do not exactly reproduce the structure of the reference marking field in the detector plane.
• aperiodic structures on the side of the reference marking field and detector-side structures are specifically coordinated.
• preamplifier or current-voltage converter can be arranged in front of the respective summing elements SUM1 - SUM4.
• the sum signal present at the output of the first summing element SUM1 is switched to the first input of a difference-forming element DIF1 in order to generate the incremental signal INC 0 .
• the desired first incremental signal INC 0, which is free of DC components, is then present at the output of the difference-forming element DIF1.
• Detector areas GR EF1 - GREF4 connected to each other; analogously, this takes place with respect to the active detector areas with k 2-4.
• the combined signal components of these selected detector areas are then added up via a summing element SUM6 and the resulting sum signal is switched to the first input of a difference-forming element DIF3.
• a reference signal is present at the second input of this difference-forming element DIF3 and is generated from all the signal components of the active detector areas D1-D44 connected in sum, which ultimately corresponds to a so-called constant light signal.
• the desired reference pulse signal REF again results at the output of the difference-forming element DIF3.
• a signal could also be applied to the second input of the difference-forming element DIF3, which only results from the summation of the signal components of the incremental signal detector areas. Accordingly, the reference signal would not be a uniform signal with a constant signal level, but a so-called counter clock signal.
• the incremental signals generated in the manner according to the invention ie INC 0 , INCgo are again shown in FIG. 3b; Likewise, the reference pulse signal REF at the reference position x Re f is shown in this representation. As can also be seen from this merely schematic representation, the incremental signals INC 0 , INCgo can thus be generated in addition to the reference pulse signal REF in the spatial area of the reference position x Re f based on the inventive measures explained.
• the reference pulse signal REF now has no modulated signal component with the period of Incremental signals INC 0 , INCgo more on.
• FIG. 4a A third embodiment of the scanning unit according to the invention is shown in FIG. 4a in connection with a part of the scale scanned with it.
• a reference marking field 70 is in turn integrated in the incremental graduation track 90 with the incremental graduation 80 on the scale.
• the design of the reference marking field 70 a slightly different variant has now been selected in this exemplary embodiment.
• the reference marking field 70 only three reference marking subareas 70.1, 70.7 and 70.19 are different from the periodic one Arrangement of permeable and impermeable sub-areas designed to be impermeable.
• the detector arrangement 406 shown in turn comprises a number of identical detector areas D401-D428, which are arranged adjacent to one another in the measuring direction x and are used to generate the incremental signals INC 0 , INC «and also to generate the reference pulse signal REF.
• specific reference pulse signal detector areas are selected from the existing detector areas depending on the design of the reference marking field 7 on the scale.
• the detector areas D409, D410, D413, D414, D421 and D422 serve as reference pulse signal detector areas for generating a reference pulse signal REF at a defined reference position.
• the arrangement or selection of the reference pulse signal detector areas takes place depending on the position of those partial areas 70.1, 70.7 and 70.19 which destroy the periodicity of the scanned structure in the reference marking field 70 on the scale.
• the remaining detector areas of the detector arrangement 406 in turn function as incremental signal detector areas, which are primarily used to generate the incremental signals INC 0 , INCgo. This includes the detector areas D401 - D408, D411 - D412, D415 - D420 and D423 - D428.
• the third exemplary embodiment shown in FIG. 4a now differs essentially in two points from the previous exemplary embodiment of the scanning unit according to the invention.
• the variant according to FIG. 3a thus made a so-called single-field scanning possible, in which all signal components for generating incremental and reference pulse signals each a division period of the scale; In the exemplary embodiment in FIG. 4a, however, a so-called Vernier scan is implemented.
• Vernier scanning is now implemented.
• the successive arrangement of the different detector areas D401-D428 consequently deviates from the arrangement explained in FIG. 2a, in particular the phase relationships of the signals from the individual, adjacent detector areas D401-D428 differ.
• a Vernier scan is generally understood to mean a scan of a periodic scale structure by means of a periodic scan structure, the center distances of in-phase detector areas being greater than the period of the intensity pattern generated by the scale in the detector plane. The periodicities of the scale and scanning structure therefore differ.
• FIG. 4a shows a further variant for filtering the modulated, periodic incremental signal component in the reference pulse signal REF, as will be explained below.
• incremental signal detector areas are connected to one another in accordance with FIG. 4a, which provide in-phase signal components during the scanning.
• two of the corresponding four signals each with a 90 ° different phase position, reach the inputs of summing elements SUM401, SUM402, to which a signal component is also fed via the second input, which is derived from the interconnected reference pulse signal Detector areas D409, D410, D413, D414, D421, D422 with the same phase position as the incremental signal.
• the signals present at the outputs of the summing elements SUM401, SUM402, as well as the remaining incremental signal components, are finally fed in the manner shown to two difference-forming elements DIF401 and DIF402, at whose outputs the DC component-free incremental signals INC 0 , INC 90 are applied.
• the outputs of the selected reference pulse signal detector areas D409, D410, D413, D414, D421, D422 are interconnected, each with the same phase position, and the two phase-different signal components are added up via the summing element SUM404. Accordingly, the output signals of the reference pulse signal detector areas D409, D413, and D421 are connected to one another, which have the phase position 0 °; analogously, this is done with the reference pulse signal detector areas D410, D414 and D422, which each have a phase angle of 270 °.
• the first reference pulse signal component RT present at the output of the summing element SUM404 is fed to a first input of a difference-forming element DIF403.
• a second reference pulse signal component RGT is present at the second input of the difference-forming element DIF403.
• the second reference pulse signal component RGT has a phase position, in particular in the area adjacent to the reference position x REF , which makes it possible to eliminate or filter out the undesired incremental signal component in the reference pulse signal REF by forming the difference from the two signal components RT, RGT.
• the phase position or phase shift required for this Signal components can be suitably adjusted by the appropriate interconnection or amplification of the signal components with the same phase position or all signal components.
• the difference formation from the two reference pulse signal components RT, RGT takes place with the help of the previously mentioned difference formation element DIF403.
• the desired reference pulse signal REF is present at its output, which adjacent to the reference position x REF no longer has any modulated incremental signal component.
• the exemplary embodiment in FIG. 4a provides for summing the phase-different signals present at the outputs of the two summing elements SUM401, SUM402 with the aid of a further summing element SUM403.
• the signal RGT present at the output of the summing element SUM403 is then as described, the second input of the differential formation element DIF403 supplied.
• an amplifier element AMP401 with a defined selected or adjustable gain factor is further arranged after the summing element SUM404.
• the signal levels of the signals RT and RGT can be suitably selected via this amplifier element, which is important in this exemplary embodiment insofar as a different number of detector areas was used to form the two signals RT and RGT and accordingly different signal intensities result.
• a further amplifier element can also be arranged between the summing element SUM403 and the difference-forming element DIF403. As already mentioned above, an electronic addition of a suitable offset to one of the two signal components would also be possible.
• FIGS. 4a-4c The signal course of the two generated reference pulse signal components RT, RGT in the area of the reference position x REF and the reference pulse signal REF ultimately resulting in the difference formation is outlined in FIGS. 4a-4c.
• FIG. 4c also shows a trigger threshold TS, with the aid of which a square-wave signal can be generated from the reference pulse signal REF in a known manner using a trigger element (not shown).
• this embodiment In order to eliminate the undesired incremental signal component in the reference pulse signal REF, it is therefore provided in this embodiment to generate at least two reference pulse signal components with such a relative phase position that this periodic incremental signal component can be eliminated by combining the different reference pulse signal components, particularly adjacent to the reference position. Depending on the phase position of the generated reference pulse signal component, this can be done by adding or forming a difference, etc.
• this can be done by adding or forming a difference, etc.
• FIG. 5 shows a further development of the third exemplary embodiment, on the basis of which a fourth exemplary embodiment of the scanning unit according to the invention will be explained.
• the structure of the scanning arrangement 506 shown is similar to the previous exemplary embodiment. Of the detector areas D501-D548, certain detector areas in turn serve as reference pulse signal detector areas D517, D518, D525, D526, D537, D538, D541, D542. These were again chosen depending on the chosen design of the reference marking field 7 on the scale. The remaining detector areas of the detector arrangement 506 act as incremental signal detector areas.
• the two incremental signals INC 0 , INCgo are generated in principle as in the previous exemplary embodiment, to which reference is made here only.
• the exemplary embodiment in FIG. 5 now differs from the variant explained above in that an alternative generation of the different reference pulse signal components RT, RGT is provided, which are ultimately used to form the reference pulse signal REF.
• RGT reference pulse signal component
• another variant is provided for generating the second reference pulse signal component RGT, which is supplied to the difference forming element DIF503 in addition to the first reference pulse signal component RT.
• RGT the second reference pulse signal component
• Suitable incremental signal detector areas are selected with a view to the best possible suppression of interfering signal peaks of the reference pulse signal REF outside the reference position XR EF .
• amplifier elements AMP1-AMP7 are arranged in the signal connecting lines of all in-phase connected detector areas, each of which has a defined adjustable gain characteristic.
• the gain characteristic of these amplifier elements AMP1-AMP7 is set in such a way that, in particular when the difference is formed from the two reference pulse signal components, the undesired incremental signal component in the reference pulse signal REF is eliminated via the difference forming element DIF503. This means that it is therefore ensured in this way that in the area adjacent to the Reference position XR EF the different reference pulse signal components RT, RGT have essentially the same amplitudes.
• FIG. 6 shows a top view of the detector level of a structured detector arrangement 606 with different signal processing components.
• the structured detector arrangement 606 in turn comprises a series of detector regions D600-D631 which are arranged adjacent to one another in the measuring direction x. As already explained in the second exemplary embodiment, this can be done, for example, by suitable structuring of a semiconductor substrate.
• not only active detector areas D600-D631 are provided for generating the reference pulse signal REF and the phase-shifted incremental signals INC 0 , INCgo, all of which are of identical design.
• the four reference pulse signal detector areas D612, D617, D626 and D627 which are used to generate the reference pulse signal REF, have a different form from the identical, remaining incremental signal detector areas D600-D611, D613-D616, D618-D625, D628-D631 which are used to generate the incremental signals INC 0 , INCgo.
• the shape of the reference pulse signal detector areas D612, D617, D626 and D627 was chosen in such a way that this results in an optical filtering of the signal component modulated onto the reference pulse signal REF with the period of the incremental signals INC 0 , INCgo.
• reference pulse signal detector areas D612, D617, D626 and D627 are offset from one another by half a division period of the scanned scale division.
• the desired filtering or an extinction of the incremental signal components modulated in phase on the reference pulse signal REF results.
• other geometric shapes of the reference pulse signal detector areas can also be selected in order to achieve the desired filter effect.
• the output signals of the reference pulse signal detector areas D612, D617, D626 and D627 are fed to a first input of a difference-forming element DIF603 in this embodiment.
• a signal is present at the second input of the difference forming element DIF603, which results from the summation of the output signals of all incremental signal detector areas D600 - D611, D613 - D616, D618 - D625, D628 - D631 via the summing element SUM.
• the phase-shifted incremental signals INC 0 , INC 90 are basically generated analogously to the previous exemplary embodiments. Thus, it is provided in each case to interconnect the in-phase output signals of the incremental signal detector areas and to supply two difference-forming elements DIF601 and DIF602 in the known manner. The two phase-shifted incremental signals INC 0 , INCgo are then again present at the output of the two difference-forming elements DIF601 and DIF602 for further processing.
• FIGS. 7a-7d Further possibilities for the advantageous configuration or modification of the scanning unit according to the invention are explained below with the aid of FIGS. 7a-7d. This should firstly make it clear that within the scope of the present invention it is by no means imperative to always use groups of four active detector areas within the reference pulse signal detector areas to generate a reference pulse signal, the spatial position in the structured detector arrangement having a correlation with the structure of the reference marking field to be scanned.
• more than four, correctly connected, active detector areas of a structured detector arrangement can be used.
• this is shown, for example, with five active detector areas D35-D39 of a detector arrangement 36, which are connected in the correct phase to generate the desired reference pulse signal.
• the above-mentioned filtering of the undesired incremental signal component in the reference pulse signal can again be ensured if the same number of detector areas are interconnected for each phase position.
• the active reference pulse signal detector areas D35 '- D39' which are primarily used to generate the reference pulse signal, over the full width of the incremental division track use, but only to use a partial area of the active detector areas D35 ' - D39 ' to generate the scanning signals.
• the active detector areas selected for generating the reference pulse signal can have approximately different lengths, as is shown, for example, in FIG. range D35 ' - D39' is indicated.
• signal components from identical active detector areas could also be amplified differently for this purpose.
• the active detector areas not be rectangular, but for example to provide detector areas whose edges are sinusoidal in the measuring direction.
• the signals from detector areas with different phase positions, which are used for generating the reference pulse signal, can also be amplified differently so as to optimize the width of the reference pulse signal.
• individual or all detector areas can be arranged at irregular intervals. In this way, the harmonic content of the Reduce incremental signals or achieve the filter effect mentioned above.
• the reference marking field integrated in the incremental track can also be created instead of converting light fields into dark fields by converting dark fields into bright fields.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optical Transform (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)
• Body Structure For Vehicles (AREA)
• Vehicle Body Suspensions (AREA)
• Eye Examination Apparatus (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7838220

Family Applications (1)

Country Status (6)

Cited By (8)

Families Citing this family (52)

Citations (2)

Family Cites Families (18)

• 1998
  • 1998-07-10 EP EP98112848A patent/EP0896206B1/de not_active Expired - Lifetime
  • 1998-07-10 DE DE59806597T patent/DE59806597D1/de not_active Expired - Lifetime
  • 1998-07-10 DE DE19830925A patent/DE19830925A1/de not_active Withdrawn
  • 1998-07-10 AT AT98112848T patent/ATE229642T1/de not_active IP Right Cessation
  • 1998-07-24 JP JP2000506501A patent/JP2001512818A/ja active Pending
  • 1998-07-24 WO PCT/EP1998/004658 patent/WO1999008074A1/de not_active Ceased
  • 1998-07-24 DE DE59806554T patent/DE59806554D1/de not_active Expired - Lifetime
  • 1998-07-24 EP EP98945093A patent/EP1002219B1/de not_active Expired - Lifetime
  • 1998-07-24 AT AT98945093T patent/ATE229171T1/de not_active IP Right Cessation
  • 1998-07-24 DE DE19833439.7A patent/DE19833439B4/de not_active Expired - Fee Related
  • 1998-07-24 US US09/485,358 patent/US6392224B1/en not_active Expired - Lifetime
  • 1998-08-06 JP JP22321898A patent/JP4324261B2/ja not_active Expired - Fee Related
  • 1998-08-07 US US09/130,702 patent/US6198534B1/en not_active Expired - Lifetime

Patent Citations (2)

Also Published As

Similar Documents

Legal Events