Optical position measuring device

Abstract

To obtain an optical position measurement device based on vernier scanning without being affected by dirt of a measurement scale.SOLUTION: An optical position measurement device detects the positions of two objects which are relatively movably arranged along a measurement direction x. The optical position measurement device includes: a scale 10 which has a measurement scale 11 connected to one of both the objects; a scanning unit which is connected to the other object; a light source 21; a scanning plate 23 which has scanning scales 24.1 and 24.2 having scanning scale periodicity different from a measurement scale periodicity; deflection elements 25.1 and 25.2 which generate deflection of a beam flux entering through the scanning scales 24.1 and 24.2; and detector arrangement structures 26.1 and 26.2 which are generated in a form of a periodic vernier striped pattern in which the beam flux has a striped pattern periodicity. The detector arrangement structures 26.1 and 26.2 have photosensitive detection elements which are periodically arranged along the measurement direction x.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical position measuring device for detecting the positions of two objects arranged to be movable relative to each other along a measurement direction.

Background Art

[0002] Generally, a known optical position measuring device for detecting the positions of two objects movable relative to each other includes a scale having a measurement scale attached to one of the two objects, and a scanning unit arranged on the other object. Usually, the scanning unit includes a light source, a scanning plate, and a properly formed detector arrangement structure. On the scanning plate, optical components such as one or more scanning scales are arranged. The beam bundle emitted from the light source hits the scale and at least one scanning scale one or more times each along the scanning beam path before the beam bundle hits the detector arrangement structure. When the scale and the scanning unit move relative to each other along the measurement direction, a plurality of scanning signals modulated and phase-displaced depending on the displacement are generated via the detector arrangement structure, and the scanning signals are further processed in subsequent electronics.

[0003] Such a position measuring device can be used, for example, in a machine tool to detect the relative positions of machine components movable relative to each other. In particular, at this time, under rough ambient conditions, the measurement scale on the scale may be soiled, for example, by oil, a cooling medium, or wear debris. If it gets soiled in this way, the functionality of the position measuring device may be impaired.

[0004] To minimize the problems that occur at this time, so-called single-field scanning is known. For this, see, for example, Patent Document 1. Here, it is ensured via appropriate optical measures or an appropriate scanning beam path that phase-shifted scanning signals are each generated based on scanning of the same measurement scale range. In this way, all scanning signals are similarly affected by possible dirt in some cases, whereby further signal processing is slightly inhibited, for example, more than by the unequal effects due to dirt of individual scanning signals.

[0005] In contrast, in the so-called Vernier scanning that is often used for signal generation in an optical position measuring device (for this, see Patent Document 2), there is no pure single-field scanning. Such Vernier scanning is characterized in that the measurement scale and the scanning scale used have slightly different periodicities, and a periodic Vernier fringe pattern is generated in the detection plane based on the interaction between different scales in the scanning beam path and the beam bundle emitted from the light source. When the measurement scale is dirty or there is a local measurement scale defect, in such a system, an unequal effect of the generated scanning signals occurs. This also results in an error during further processing and especially during the positioning made thereby.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem underlying the present invention is to obtain an optical position measuring device based on Vernier scanning that is not affected by dirt of the measurement scale as much as possible.

Means for Solving the Problem

[0008] This problem is solved by an optical position measuring device having the features of claim 1 according to the present invention.

[0009] Advantageous embodiments of the optical position measuring device according to the present invention are apparent from the measures described in the dependent claims.

[0010] The optical position measuring device according to the present invention for detecting the positions of two objects that are relatively movable with respect to each other along a measurement direction includes a scale coupled to one of the two objects and a scanning unit coupled to the other of the two objects. The scale has a measurement scale with a predetermined measurement scale periodicity while extending along the measurement direction. The scanning unit includes at least one light source, a scanning plate, and at least two detector arrangement structures. Here, the scanning plate has at least two scanning scales, and the scanning scales are arranged adjacent to each other on one side of the scanning plate perpendicular to the measurement direction and each has a predetermined scanning scale periodicity, and the scanning scale periodicity is different from the measurement scale periodicity. Also, at least two direction-selective deflection elements are provided, and the deflection elements are assigned to at least two scanning scales and deflect a beam bundle entering through different scanning scales in the direction of a common hitting partial range in the measurement scale. The beam bundles incident from the hitting partial range in the measurement scale in the form of a periodic Vernier fringe pattern having a stripe pattern periodicity hit at least two detector arrangement structures. Each detector arrangement structure includes a plurality of photosensitive detector elements, and the detector elements are periodically arranged along the measurement direction.

[0011] Preferably, the at least two detector arrangement structures are arranged adjacent to each other in the direction perpendicular to the measurement direction.

[0012] Here, - The detector elements of the detector arrangement structure are each formed in a rectangular shape, and the rectangular longitudinal axes are each oriented parallel to the perpendicular to the measurement direction, and - The detector elements are arranged in a straight line with respect to each other along the perpendicular to the measurement direction is possible.

[0013] The detector elements of the detector arrangement structure that are arranged adjacent to each other along the perpendicular to the measurement direction can be electrically connected to each other.

[0014] Advantageously, - The scanning unit includes two detector arrangement structures, - Within one period of the Vernier fringe pattern to be scanned, one detector group having four identically formed detector elements is arranged along the measurement direction, and a plurality of detector groups in each detector arrangement structure are arranged along the measurement direction, - When the scale and the scanning unit move relative to each other, the four detector elements of the detector group of the first detector arrangement structure each supply a periodic output signal having phase positions of 180°, 270°, 0°, and 90°, - When the scale and the scanning unit move relative to each other, the four detector elements of the detector group of the second detector arrangement structure each supply a periodic output signal having phase positions of 0°, 90°, 180°, and 270°, - In order to obtain a first scanning signal dependent on displacement, the following detector elements of adjacent detector groups of both detector arrangement structures are electrically connected to each other, and these following detector elements are the third detector element of the first detector arrangement structure, the first detector element of the second detector arrangement structure, the first detector element of the first detector arrangement structure, the third detector element of the second detector arrangement structure, - In order to obtain a second scanning signal that is phase-shifted by 90° with respect to the first scanning signal and is dependent on displacement, the following detector elements of adjacent detector groups of both detector arrangement structures are electrically connected to each other, and these detector elements are The fourth detector element of the first detector arrangement structure, the second detector element of the second detector arrangement structure, the second detector element of the first detector arrangement structure, the fourth detector element of the second detector arrangement structure is.

[0015] Also, it can be formed as an amplitude-phase grating with mixed scanning graduations, and the amplitude-phase grating is composed of periodic amplitude structures and phase structures alternately arranged in the measurement direction and is arranged on the side facing the scale on the scanning plate.

[0016] At this time, - The amplitude structure includes transmissive and non-transmissive graduation ranges, - The phase structure includes identically formed transmissive graduation ranges each having an optical phase shift effect can be configured as follows.

[0017] Here, - The scanning graduations are each composed of a plurality of scanning graduation unit gratings arranged periodically along the measurement direction with scanning graduation periodicity, - The scanning graduation unit grating includes a first non-transmissive graduation range, a transmissive graduation range, a second non-transmissive graduation range, and a phase shift graduation range along the measurement direction, - The adjacent non-transmissive graduation ranges are arranged at an interval of half of the scanning graduation periodicity, and the adjacent transmissive graduation ranges and the adjacent phase shift graduation ranges are arranged at an interval of the scanning graduation periodicity with respect to each other is possible.

[0018] Here, further, the scanning graduation periodicity (TP A ) is respectively TP A = 2 / (1 / TP M ± 1 / SP) is selected according to, where TP A = scanning graduation periodicity TP M=Measurement scale periodicity SP = Striped pattern periodicity It is possible to be.

[0019] Furthermore, - The detector arrangement structures are each formed identically, - The detector arrangement structures are arranged on the scanning plate adjacent to each other along the perpendicular to the measurement direction, - Adjacent scanning scales are TP to each other along the measurement direction A / 2 offset, or TP A / 4 offset and arranged on the scanning plate, TP A represents the scanning scale periodicity It is possible to be.

[0020] Preferably, the direction-selective deflection element is arranged between the light source and the scanning plate in the scanning unit.

[0021] Here, the direction-selective deflection element is arranged on the side of the scanning plate facing the light source and can be formed as a multi-stage blazed phase grating.

[0022] Advantageously, - Two phase gratings as direction-selective deflection elements are each formed as a four-stage blazed phase grating and arranged on the scanning plate adjacent to each other along the perpendicular to the measurement direction. An absorptive partial range is located on the scanning plate between the deflection elements. - Both phase gratings are configured to have opposite directions of the stepped cross-section progression. It is configured like this.

[0023] Alternatively, the direction-selective deflection element - is formed as a refractive prism wedge, or - is formed as a multi-segment lens, and the segments of the multi-segment lens have optical axes inclined with respect to each other. It is also possible to be.

[0024] As a special advantage of the optical position measuring device according to the present invention, a stable scanning signal can be obtained even in the case of a locally soiled measuring scale or in the case of a local measuring scale defect. The amplitude and offset of the phase-shifted scanning signal of the optical position measuring device according to the present invention now change in the same manner even in the above cases by the set single-field scan, i.e., there is no greater amplitude ratio variation and scan ratio variation in different scanning signals, and thus no additional position error occurs.

[0025] Further details and advantages of the present invention will be explained below based on the description of an embodiment of the optical position measuring device according to the present invention in connection with the drawings.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0027] Hereinafter, an embodiment of the optical position measuring device according to the present invention will be described based on FIGS. 1 to 5. Here, FIG. 1 is a cross-sectional view for explaining the scanning beam path, FIGS. 2, 3, and 4 are views showing the upper side, lower side, and partial cross-sectional view of the scanning plate, and FIG. 5 is a plan view of the detection plane.

[0028] The illustrated position measuring device is used to detect the positions of two objects that are movable relative to each other along at least one measuring direction x. In this example, a relative movement of the objects along the linearly extending measuring direction x is set, that is, the optical position measuring device according to the invention is here formed as a length measuring device. The objects movable relative to each other are not shown in each figure, but here may be, for example, two mechanical components movable relative to each other. The movement of both mechanical components can be controlled via a subsequent mechanical control unit using a scanning signal that depends on the displacement generated by the position measuring device. At this time, a scale 10 of the position measuring device is coupled to one of the two objects, and a scanning unit 20 of the position measuring device is coupled to the other object.

[0029] Here, the scale 10 formed as a linear scale has a measuring scale 11 extending in the measuring direction x, and the measuring scale is arranged on a suitable support. The grid-like measuring scale 11 is composed of scale ranges with different optical effects that are periodically arranged along the measuring direction x with a scale periodicity TP M and is configured with scale ranges having different optical effects arranged periodically along the measuring direction x with a scale periodicity TP M represents the width of two adjacent scale ranges having different optical characteristics along the measuring direction x. In a possible embodiment, the scale periodicity TP M = 20 μm is set.

[0030] This embodiment of the optical measuring device according to the invention is formed as an incident light system. This means that with respect to the formation of the measuring scale 11, the measuring scale is formed as a reflection measuring scale and has various scale widths with different reflection characteristics, and thus has, for example, a low reflection scale range and a high reflection scale range. Instead of this, it is also possible to set different phase shift effects of the reflecting scale ranges of the measuring scale 11.

[0031] In the optical position measuring device according to the present invention, on the side of the scanning unit 20, a light source 21 having a collimation optical system arranged in front, a scanning plate 23, and two detector arrangement structures 26.1 and 26.2 are provided. Here, the beam bundle emitted from the light source 21 is collimated through the collimation optical system 22 and reaches the scanning plate 23 where a structured optically effective predetermined range passes before the operation scale 11 abuts on the scale 10. From there, a rear reflection occurs in the direction of the scanning unit 20, and in the scanning unit, subsequently, the scanning plate 23 passes newly in the unstructured range. Due to the interaction of the beam bundle with the structured range of the scanning plate 23 and the measurement scale 11, a so-called Vernier fringe pattern is generated in the detection planes of both detector arrangement structures 26.1 and 26.2.

[0032] In the illustrated embodiment, on the side of the scanning plate 23 facing the scale 10, two scanning scales 24.1 and 24.2 or a structured range or an optically effective range of scanning gratings adjacent to each other perpendicular to the measurement direction x are arranged, and this range is passed during the first pass of the scanning plate 23. The scanning scales 24.1 and 24.2 are each composed of scale ranges having different optical actions periodically arranged along the measurement direction x with a scanning scale periodicity TP A . Here, the scanning scale periodicity TP A is different from the measurement scale periodicity TP M in a preset manner. In this embodiment, the above measurement scale periodicity TP M = 20 μm, for example, the operation scale periodicity TP A = 39.04239 μm is set. Further details of the operation scales 24.1 and 24.2 will be described in more detail in the course of the explanation.

[0033] In this embodiment, on the opposite side of the scanning plate 23 facing the light source 21, there are two deflection elements 25.1 and 25.2 that are structured and have a directionally selective optically effective range, and the deflection elements are assigned to both operation scales 24.1 and 24.2. By the deflection elements 25.1 and 25.2, the beam bundle entering through the operation scales 24.1 and 24.2 is deflected so that the beam bundle hits a common partial range at the measurement scale 11. In this regard, it is guaranteed that all the generated scanning signals come from the scanning of the same partial range of the measurement scale 11, thereby making it possible to guarantee a single-field scanning that is less affected by dirt.

[0034] Due to the interaction of the beam bundle emitted from the light source 21 with the directionally selective deflection elements 25.1 and 25.2, the scanning scales 24.1 and 24.2, and the partial range where the measurement scale 11 (the beam bundle) hits, periodic Vernier fringe patterns are respectively generated in the detection planes of both detector arrangements 26.1 and 26.2. The Vernier fringe patterns have the same fringe pattern periodicity SP, but are different from each other in their relative phase positions due to the relative arrangement of both scanning scales 24.1 and 24.2 on the scanning plate 23. Scanning scale periodicity TP A and measurement scale periodicity TP M In the selection, as described above, the fringe pattern periodicity SP = 800 μm. Both Vernier fringe patterns are converted into electrical output signals through the two detector arrangements 26.1 and 26.2, and the output signals are further processed into two or more scanning signals with a phase shift. For this purpose, both detector arrangements each include a plurality of photosensitive detector elements, and the detector elements are periodically arranged along the measurement direction x and are electrically connected (wired) to each other in an appropriate manner.

[0035] Hereinafter, based on FIGS. 2, 3, and 4, the formation of the scanning plate 23 having the components arranged thereon will be described in detail.

[0036] Here, FIG. 2 shows a plan view of the lower side of the scanning plate. The lower side of the scanning plate faces the scale, and both scanning graduations 24.1 and 24.2 are arranged on the lower side of the scanning plate. In this embodiment, both scanning graduations 24.1 and 24.2 are formed as a mixed amplitude-phase grating and are composed of periodic amplitude structures and phase structures alternately arranged in the measurement direction x. Here, the amplitude structure includes a non-transmissive graduation range 24.1b and a transmissive graduation range 24.1c. The phase structure is composed of graduation ranges 24.1a that are identically formed and have a defined phase shift optical effect on the passing beam bundle. In connection with such a mixed amplitude-phase grating, reference is additionally made to European Patent Application No. 1081457 already mentioned at the beginning.

[0037] Scanning graduation periodicity TP A In the case of such a configuration of the scanning graduations 24.1 and 24.2, as can be seen from FIG. 2, it represents the width of four consecutive graduation ranges of the scanning graduation unit lattice along the measurement direction x, that is, from the left, the first non-transmissive graduation range 24.1b having a defined phase shift effect, the transmissive graduation range 24.1c, the second non-transmissive graduation range 24.1b, and the width of the partial range 24.1a. At this time, TP A / 2 represents the interval between two consecutive non-transmissive graduation ranges 24.1b within the scanning graduation 24.1 or 24.2 having two non-transmissive graduation ranges 24.1b per scanning graduation unit lattice configured as such. Therefore, the interval corresponds to half of the scanning graduation periodicity. In such scanning graduations 24.1 and 24.2, TP A represents the interval between adjacent phase shift graduation ranges 24.1a or the interval between adjacent transmissive graduation ranges 24.1c, and thereby corresponds to the scanning graduation periodicity. The complete scanning graduation 24.1 or 24.2 is respectively composed of such a periodic succession of scanning graduation unit lattices along the measurement direction x having the scanning graduation periodicity TP A

[0038] ​To generate a Vernier fringe pattern having a desired fringe pattern periodicity SP through optical interaction of a beam bundle with an optical structure that passes through or hits both detector arrangement structures in the beam path, the scanning scale periodicity TP A needs to be dimensioned in a predetermined manner. The required scanning scale periodicity TP A is, in a preset measurement scale periodicity TP M and the desired fringe pattern periodicity SP, for the scanning scales 24.1, 24.2 thus formed, is obtained in a general form according to the following relationship: TP A = 2 / (1 / TP M ± 1 / SP) Here, TP A = scanning scale periodicity TP M = measurement scale periodicity SP = fringe pattern periodicity

[0039] Instead of the above-described dimensioning example with a scanning scale periodicity TP A having, according to this relationship, a scanning scale periodicity TP A = 41.02564 μm can also be selected.

[0040] Furthermore, as can be seen from FIG. 2, both scanning scales 24.1, 24.2 are formed identically and are arranged adjacent to each other along a perpendicular y to the measurement direction x on the scanning plate 23 or below the scanning plate. Here, in this embodiment, a shift TP A / 2 is set between two adjacent scanning scales 24.1, 24.2. As a result, the two generated Vernier fringe patterns have a relative phase shift of 180° with respect to each other in the detection plane of the detector arrangement structures 26.1, 26.2.

[0041] FIG. 3 shows a plan view of the upper side of the scanning plate, which faces the light source. On the upper side of the scanning plate, direction-selective deflection elements 25.1 and 25.2 are arranged. Here, the deflection elements are formed as multi-stage blazed phase gratings. This means that an appropriate phase grating is optimized such that the diffraction efficiency for a given diffraction order is maximized, while the diffraction efficiency for other diffraction orders is minimized. Specifically, two four-stage blazed phase gratings are provided, and the blazed phase gratings are arranged on the scanning plate 23 adjacent to each other along a perpendicular line y to the measurement direction x. Between the two blazed phase gratings, an absorptive partial range 27 is formed on the scanning plate 23. Further, as can be seen from the partial cross-sectional view of the scanning plate in FIG. 4, the two blazed phase gratings of the deflection elements 25.1 and 25.2 have the opposite direction of the stepped cross-sectional profile. This ensures the necessary deflection action on the passing beam bundle, and as a result, the beam bundle hits a common partial range in the measurement scale.

[0042] A plan view of a detection plane having both detector arrangement structures 26.1 and 26.2 is shown in FIG. 5. As can be seen from FIG. 5, the detector arrangement structures 26.1 and 26.2 are arranged adjacent to each other in the scanning unit in the direction of the perpendicular line y with respect to the measurement direction x. Both detector arrangement structures 26.1 and 26.2 are each composed of a plurality of photosensitive detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d, and the detector elements are periodically arranged along the measurement direction x. Such a detector arrangement structure is also called a structured photodetector. Here, as the photosensitive detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d, a photodiode having a photosensitive surface formed in a rectangular shape is worth considering. Here, the rectangular long axes are each oriented parallel to the perpendicular line y with respect to the measurement direction x. Also, in the illustrated embodiment, the detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d of both detector arrangement structures 26.1 and 26.2 are arranged in a straight line with respect to each other along the perpendicular line y with respect to the measurement direction x. At this time, the adjacent detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d in both detector arrangement structures 26.1 and 26.2 are electrically connected (wired) to each other.

[0043] In this embodiment, the dimensions of both detector arrangement structures 26.1 and 26.2 are set so that one detector group composed of four identical detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d is provided within the period of the scanned Vernier fringe pattern. And the detector arrangement structures 26.1 and 26.2 each include a plurality of such detector groups along the measurement direction x. At this time, the number of detector groups in each detector arrangement structure 26.1 and 26.2 is adapted to the number of periods in the generated Vernier fringe pattern.

[0044] In the first detector arrangement structure 26.1, the four detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d of the detector group supply periodic output signals having phase positions of 180°, 270°, 0°, and 90° respectively when the scale and the scanning unit move relative to each other and when the Moiré fringe pattern generated at this time is scanned. That is, from the left, the first detector element of the detector group supplies an 180° output signal, the second detector element supplies a 270° output signal, and so on.

[0045] And in the second detector arrangement structure 26.2, based on the scanning of the phase-displaced (phase-shifted) Moiré fringe pattern, as can be seen from FIG. 5, periodic output signals having phase positions of 0°, 90°, 180°, and 270° are generated in the detector group.

[0046] Based on the output signals of the detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d thus generated, in order to generate two scanning signals SIN and COS that are 90° phase-shifted and dependent on displacement, the detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d of both detector arrangement structures need to be electrically connected (wired) to each other in a defined manner. Therefore, in order to generate the first scanning signal SIN, the following detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d of adjacent detector groups among both detector arrangement structures 26.1 and 26.2 are electrically connected (wired) to each other respectively, and these following detector elements are the third detector element (26.1c) of the first detector arrangement structure (26.1), the first detector element (26.2a) of the second detector arrangement structure (26.2), the first detector element (26.1a) of the first detector arrangement structure (26.1), and the third detector element (26.2c) of the second detector arrangement structure (26.2).

[0047] In contrast, the second scanning signal COS that is phase-shifted by 90° is generated in the position measuring device according to the present invention by electrically connecting (wiring) the following detector elements 26.1a, ··· 26.1d, 26.2a, ··· 26.2d of adjacent detector groups among the two detector arrangement structures 26.1 and 26.2 to each other. These detector elements are the fourth detector element (26.1d) of the first detector arrangement structure (26.1), the second detector element (26.2b) of the second detector arrangement structure (26.2), the second detector element (26.1b) of the first detector arrangement structure (26.1), and the fourth detector element (26.2d) of the second detector arrangement structure (26.2).

[0048] Then, the scanning signals SIN and COS generated in such a manner can be further processed in a known manner in subsequent electronic equipment arranged subsequent to the position measuring device.

[0049] In addition to the above-described embodiments, of course, there are other possible configurations within the scope of the present invention.

[0050] Therefore, it is also possible to form the optical position measuring device according to the present invention for detecting the rotational relative movement of two objects. In this case, a circular scale or a radial scale with the center as the rotation axis is required.

[0051] In order to detect the rotational relative movement, so-called cylindrical (drum) scanning can also be realized. At this time, the scale is arranged, for example, on a band, and the band is provided around a drum that rotates around the rotation axis and is scanned by an opposing stationary scanning unit.

[0052] Instead of the above-described mode of incident light, of course, it is also possible to realize the mode of transmitted light of the position measuring device according to the present invention. For this purpose, the scale can be formed as a transmission scale, and the transmission scale is composed of alternately arranged scale ranges having different optical transparencies.

[0053] It is also possible to provide more than two scanning graduations on the scanning plate. Therefore, it is also possible to arrange four scanning graduations on the scanning plate, which are offset from each other by TPA / 4 along the measurement direction. In this case, four direction-selective deflection elements can be assigned to the four scanning graduations, and it is possible to provide a detector arrangement structure with four detectors on the detection side. Based on the appropriate wiring of the detector elements of the four detector arrangement structures, it is similarly possible to generate both scanning signals SIN and COS that are phase-shifted by 90° and to provide them for further processing.

[0054] The scanning graduation can be formed not only as a mixed amplitude-phase grating in the above-described form, but instead, an amplitude grating can also be used as the scanning graduation. In this case, the scanning graduation periodicity TP A can be selected as follows: TP A = 1 / (1 / TP M ± 1 / SP) Here, TP A = scanning graduation periodicity TP M = measurement graduation periodicity SP = stripe pattern periodicity

[0055] In the above-described embodiment, the direction-selective deflection element is arranged on the scanning plate. However, this is not necessarily required in the optical position measuring device according to the present invention. Basically, the deflection element can also be arranged in other ways in the range between the light source and the scanning plate. For example, the optical functionality of the deflection element can be integrated into the collimation optical system, and the collimation optical system can be formed as a multi-segment lens arranged in the range. Such a multi-segment lens has segments with optical axes inclined with respect to each other, and thus, it is possible to perform the necessary deflection of the passing beam bundle.

[0056] Furthermore, instead of forming the direction-selective deflection element as a diffraction structure part in the form of a blazed phase grating, it is possible to provide a refractive prism wedge arranged on a scanning plate or the like for this purpose. Note that the present invention may also include the following aspects: 1. An optical position measuring device for detecting the positions of two objects that are relatively movable with respect to each other along a measurement direction (x), - A scale (10) coupled to one of the two objects, extending along the measurement direction (x) and having a predetermined measurement scale periodicity (TP M ) and provided with a measurement scale (11), - A scanning unit (20) coupled to the other object, The scanning unit (20) is - At least one light source (21), - Arranged on one side of a scanning plate (23) adjacent to each other perpendicular to the measurement direction (x), and having a respective predetermined scanning scale periodicity (TP M ) different from the measurement scale periodicity (TP A ) and having at least two scanning scales (24.1, 24.2), - At least two direction-selective deflection elements (25.1, 25.2) assigned to at least two scanning scales (24.1, 24.2) and causing deflection of the beam bundles incident through different scanning scales (24.1, 24.2) in the direction of the common overlapping partial range in the measurement scale (11), - At least two detector arrangement structures (26.1, 26.2) where the beam bundles incident from the overlapping partial range in the measurement scale (11) hit in the form of a periodic Vernier fringe pattern having a fringe pattern periodicity (SP) respectively, And the detector arrangement structures (26.1, 26.2) each include a plurality of photosensitive detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) arranged periodically along the measurement direction (x). An optical position measuring device characterized by this. 2. The optical position measuring device according to 1. above, characterized in that at least two detector arrangement structures (26.1, 26.2) are arranged adjacent to each other in the direction of the perpendicular (y) to the measurement direction (x). 3. - The detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of the detector arrangement structures (26.1, 26.2) are each formed in a rectangular shape, and the longitudinal axes of the rectangles are each oriented parallel to the perpendicular (y) to the measurement direction (x). - The detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) are arranged in a straight line with respect to each other along a perpendicular line (y) to the measurement direction (x). The optical position measuring device according to item 2 above, characterized by this. 4. The detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of the detector arrangement structure (26.1, 26.2), which are arranged adjacent to each other along a perpendicular line (y) to the measurement direction (x) respectively, are electrically connected to each other. The optical position measuring device according to item 3 above, characterized by this. 5. - The scanning unit (20) includes two detector arrangement structures (26.1, 26.2). - Within one period of the Vernier scale pattern to be scanned, one detector group having four identically formed detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) is arranged along the measurement direction (x). A plurality of detector groups in each detector arrangement structure (26.1, 26.2) are arranged along the measurement direction (x) respectively. - When the scale (10) and the scanning unit (20) move relative to each other, the four detector elements (26.1a, 26.1b, 26.1c, 26.1d) of the detector group of the first detector arrangement structure (26.1) supply periodic output signals having phase positions of 180°, 270°, 0°, and 90° respectively. - When the scale (10) and the scanning unit (20) move relative to each other, the four detector elements (26.2a, 26.2b, 26.2c, 26.2d) of the detector group of the second detector arrangement structure (26.2) supply periodic output signals having phase positions of 0°, 90°, 180°, and 270° respectively. - In order to obtain a first scanning signal (SIN) that depends on the displacement, the following detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of adjacent detector groups of both detector arrangement structures (26.1, 26.2) are electrically connected to each other. These detector elements are The third detector element (26.1c) of the first detector arrangement structure (26.1), the first detector element (26.2a) of the second detector arrangement structure (26.2), the first detector element (26.1a) of the first detector arrangement structure (26.1), and the third detector element (26.2c) of the second detector arrangement structure (26.2), - In order to obtain a second scanning signal (COS) that is phase - shifted by 90° with respect to the first scanning signal and is displacement - dependent, the following detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of adjacent detector groups of both detector arrangement structures (26.1, 26.2) are electrically connected to each other, and these detector elements are the fourth detector element (26.1d) of the first detector arrangement structure (26.1), the second detector element (26.2b) of the second detector arrangement structure (26.2), the second detector element (26.1b) of the first detector arrangement structure (26.1), and the fourth detector element (26.2d) of the second detector arrangement structure (26.2) The optical position measuring device according to item 3 above, characterized in that. 6. The scanning scale (24.1, 24.2) is formed as a mixed amplitude - phase grating, the amplitude - phase grating is composed of periodic amplitude structures and phase structures arranged alternately in the measurement direction (x), and is arranged on the side facing the scale (10) on the scanning plate (23). The optical position measuring device according to any one of 1 to 5 above, characterized in that. 7. - The amplitude structure includes transmissive and non - transmissive scale ranges (24.1c, 24.1b), - The phase structure includes identically formed transmissive scale ranges (24.1a) each having an optical phase - shifting effect. The optical position measuring device according to claim 6, characterized in that. 8. - The scanning scale is respectively composed of a plurality of scanning scale unit gratings arranged periodically along the measurement direction (x) with a scanning scale periodicity (TP A ) - The scanning scale unit grating includes, along the measurement direction (x), a first non - transmissive scale range (24.1b), a transmissive scale range (24.1c), a second non - transmissive scale range (24.1b), and a phase - shift scale range (24.1a). - Adjacent non - transmissive scale ranges (24.1b) have a scanning scale periodicity (TP A) are arranged at half intervals, and adjacent transmissive scale ranges (24.1c) and adjacent phase shift scale ranges (24.1a) have scanning scale periodicity (TP A ) are arranged at intervals of The optical position measuring device according to item 7 above, characterized in that. 9. Scanning scale periodicity (TP A ) are respectively TP A = 2 / (1 / TP M ± 1 / SP) is selected according to, where TP A = Scanning scale periodicity TP M = Measurement scale periodicity SP = Strip pattern periodicity The optical position measuring device according to item 6 above, characterized in that. 10. - The detector arrangement structures (24.1, 24.2) are each formed identically, - The detector arrangement structures (24.1, 24.2) are arranged adjacent to each other on the scanning plate (23) along the perpendicular (y) to the measurement direction (x), - Adjacent scanning scales (24.1, 24.2) are shifted from each other by TP A / 2, or shifted by TP A / 4 along the measurement direction (x) and arranged on the scanning plate (23), where TP A represents the scanning scale periodicity The optical position measuring device according to any one of items 1 to 9 above, characterized in that. 11. The optical position measuring device according to any one of items 1 to 10 above, characterized in that a direction-selective deflection element (25.1, 25.2) is arranged between the light source (21) and the scanning plate (23) in the scanning unit (20). 12. The optical position measuring device according to item 11 above, characterized in that the direction-selective deflection element (25.1, 25.2) is arranged on the side of the scanning plate (23) facing the light source (21) and is formed as a multi-stage blazed phase grating. 13. - Two phase gratings as direction-selective deflection elements (25.1, 25.2) are each formed as a four-stage blazed phase grating and are arranged adjacent to each other on the scanning plate (23) along the perpendicular (y) to the measurement direction (x), and an absorptive partial range (27) is located on the scanning plate (23) between the deflection elements, - Both phase gratings have mutually opposite directions of the stepped cross-sectional profile The optical position measuring device according to item 12 above, characterized in that. 14. The direction-selective deflection element is - formed as a refractive prism wedge, or - formed as a multi-segment lens, and the segments of the multi-segment lens have optical axes inclined with respect to each other The optical position measurement device according to the above item 11, characterized by this.

Claims

1. An optical position measuring device for detecting the positions of two objects that are movably arranged relative to each other along a measurement direction (x), - A scale (10) that is coupled to one of the two objects, extends along the measurement direction (x), and has a measurement scale (11) with a predetermined measurement scale periodicity (TP Ｍ ) and is provided with a measurement scale (11); - having a scanning unit (20) coupled to the other object, wherein this scanning unit (20) - has at least one light source (21), - Disposed on one side of the scanning plate (23) adjacent to each other perpendicularly to the measurement direction (x), and having a respective predetermined scanning scale periodicity (TP Ｍ ) different from the measurement scale periodicity (TP Ａ ), at least one scanning plate (23) having at least two scanning scales (24.1, 24.2), - is assigned to at least two scanning graduations (24.1, 24.2), and at least two direction-selective deflection elements (25.1, 25.2) that cause deflection of the beam bundles incident through different scanning graduations (24.1, 24.2) such that the beam bundles from the light source (21) each strike a common partial range at the measurement graduation (11), - and at least two detector arrangement structures (26.1, 26.2) at which the beam bundles incident from the struck partial range at the measurement graduation (11) each strike in the form of a periodic Vernier fringe pattern having a fringe pattern periodicity (SP), characterized in that the detector arrangement structures (26.1, 26.2) each include a plurality of photosensitive detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) that are periodically arranged along the measurement direction (x).

2. The optical position measuring device according to claim 1, characterized in that at least two detector arrangement structures (26.1, 26.2) are arranged adjacent to each other in the direction of a perpendicular (y) to the measurement direction (x).

3. - the detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of the detector arrangement structures (26.1, 26.2) are each formed in a rectangular shape, and the longitudinal axes of the rectangles are each oriented parallel to a perpendicular (y) to the measurement direction (x), - the detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) are arranged in a straight line relative to each other along a perpendicular (y) to the measurement direction (x) characterize the optical position measuring device according to claim 2.

4. The optical position measuring device according to claim 3, characterized in that detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of a detector arrangement structure (26.1, 26.2), which are arranged adjacent to one another along a perpendicular (y) to the measuring direction (x), are electrically connected to one another.

5. - The scanning unit (20) includes two detector arrangement structures (26.1, 26.2), - One detector group having four identically formed detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) is arranged along the measuring direction (x) within one period of the vernier fringe pattern to be scanned, and a plurality of detector groups in each detector arrangement structure (26.1, 26.2) are arranged along the measuring direction (x), - When the scale (10) and the scanning unit (20) move relative to each other, the four detector elements (26.1a, 26.1b, 26.1c, 26.1d) of the detector group of the first detector arrangement structure (26.1) respectively supply periodic output signals having phase positions of 180°, 270°, 0°, 90°, - When the scale (10) and the scanning unit (20) move relative to each other, the four detector elements (26.2a, 26.2b, 26.2c, 26.2d) of the detector group of the second detector arrangement structure (26.2) respectively supply periodic output signals having phase positions of 0°, 90°, 180°, 270°, - In order to obtain a first scanning signal (SIN) depending on the displacement, the following detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of adjacent detector groups of both detector arrangement structures (26.1, 26.2) are electrically connected to one another, and these detector elements are the third detector element (26.1c) of the first detector arrangement structure (26.1), the first detector element (26.2a) of the second detector arrangement structure (26.2), the first detector element (26.1a) of the first detector arrangement structure (26.1), the third detector element (26.2c) of the second detector arrangement structure (26.2), - To obtain a second scanning signal (COS) that is phase-shifted by 90° with respect to the first scanning signal and depends on displacement, the following detector elements (26.1a, 26.1b, 26.1c, 26.1d, 26.2a, 26.2b, 26.2c, 26.2d) of adjacent detector groups of both detector arrangement structures (26.1, 26.2) are electrically connected to each other, and these detector elements are the fourth detector element (26.1d) of the first detector arrangement structure (26.1), the second detector element (26.2b) of the second detector arrangement structure (26.2), the second detector element (26.1b) of the first detector arrangement structure (26.1), and the fourth detector element (26.2d) of the second detector arrangement structure (26.2). The optical position measuring device according to claim 3, characterized in that

6. The scanning scales (24.1, 24.2) are formed as a mixed amplitude-phase grating, the amplitude-phase grating is composed of periodic amplitude structures and phase structures arranged alternately in the measurement direction (x), and is arranged on the side of the scanning plate (23) facing the scale (10). The optical position measuring device according to any one of claims 1 to 5, characterized in that

7. - The amplitude structure includes transmissive and non-transmissive scale ranges (24.1c, 24.1b), - The phase structure includes transmissive scale ranges (24.1a) that are identically formed and each have an optical phase shift effect. The optical position measuring device according to claim 6, characterized in that

8. - The scanning graduations are each composed of a plurality of scanning graduation unit cells arranged with a scanning graduation periodicity (TP Ａ ) along the measurement direction (x) with periodicity. - The scanning scale unit lattice includes, along the measurement direction (x), a first non-transmissive scale range (24.1b), a transmissive scale range (24.1c), a second non-transmissive scale range (24.1b), and a phase shift scale range (24.1a). - Adjacent non-transmissive scale ranges (24.1b) are arranged at an interval that is half of the scanning scale periodicity (TP Ａ ) and adjacent transmissive scale ranges (24.1c) and adjacent phase shift scale ranges (24.1a) are arranged at an interval of the scanning scale periodicity (TP Ａ ) with respect to each other The optical position measuring device according to claim 7, characterized in that

9. Scanning scale periodicity (TP Ａ ) are each TP Ａ = 2 / (1 / TP Ｍ ± 1 / SP) is selected according to, where TP Ａ = Scanning scale periodicity TP Ｍ = Measurement scale periodicity SP = stripe pattern periodicity The optical position measuring device according to claim 6, characterized in that

10. - At least two scanning scales (24.1, 24.2) are identically formed respectively, - At least two scanning scales (24.1, 24.2) are arranged adjacent to each other on the scanning plate (23) along a perpendicular line (y) to the measurement direction (x). - Adjacent scanning graduations (24.1, 24.2) are shifted from each other by TP / 2 or TP / 4 along the measurement direction (x) and are arranged on the scanning plate (23), where TP represents the scanning graduation periodicity. Ａ / 2, or are shifted by Ａ / 4 and are arranged on the scanning plate (23), where Ａ TP represents the scanning graduation periodicity The optical position measuring device according to any one of claims 1 to 9, characterized in that

11. The optical position measuring device according to any one of claims 1 to 10, characterized in that a direction-selective deflection element (25.1, 25.2) is arranged between a light source (21) and a scanning plate (23) in a scanning unit (20).

12. The optical position measuring device according to claim 11, characterized in that the direction-selective deflection element (25.1, 25.2) is arranged on the side of the scanning plate (23) facing the light source (21) and is formed as a multi-stage blazed phase grating.

13. - Two phase gratings as direction-selective deflection elements (25.1, 25.2) are each formed as a four-stage blazed phase grating and are arranged on the scanning plate (23) adjacent to each other along a perpendicular (y) to the measurement direction (x). Between the deflection elements, an absorptive partial range (27) is located on the scanning plate (23). - Both phase gratings have mutually opposite directions of a stepped cross-section profile The optical position measuring device according to claim 12, characterized in that.

14. The direction-selective deflection element is - formed as a refractive prism wedge, or - formed as a multi-segment lens, and the segments of the multi-segment lens have optical axes inclined with respect to each other The optical position measuring device according to claim 11, characterized in that.

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