Sensing Winding Configuration for Electromagnetic Inductive Encoders

Abstract

To provide an electromagnetic induction encoder usable for measuring the relative position between two elements along a measurement axis direction.SOLUTION: An electromagnetic induction encoder includes a scale, a detection unit, and a signal processing unit. The scale includes a periodic pattern of signal modulating elements (SMEs) arranged along a measuring axis (MA) with a spatial wavelength W1. The detection unit comprises sensing elements and a field generating coil that generates a change in magnetic flux. The sensing elements comprise conductive loops and outputs detection signals in response to a local influence on the change in magnetic flux provided by adjacent SMEs. Part or all of the conductive loops are configured in accordance with an inter-loop shift relationship in which the equal "shift ratios" of the loops are shifted in opposite directions by W1 / 4K. K is an odd integer. The inter-loop shift relationship can be used for preventing the K-th spatial harmonic components of the detection signals, and can solve a long-time, harmful layout problem.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present disclosure relates to measurement instruments, and more particularly to electromagnetic induction encoders that may be utilized in precision measurement instruments. [Background technology]

[0002] Various encoder configurations may include various types of optical, capacitive, magnetic, inductive, movement and / or position transducers that measure movement between the readhead and the scale using various geometric configurations of transmitters and receivers within the readhead.

[0003] U.S. Patent No. 6,011,389 (the '389 patent), U.S. Patent No. 7,239,130 ​​(the '130 patent), and U.S. Patent No. 6,124,708 (the '708 patent) describe electromagnetic induction transducers that can be used for high-precision applications. U.S. Patent No. 5,973,494 (the '494 patent) and U.S. Patent No. 6,002,250 (the '250 patent) describe electromagnetic induction incremental calipers and linear scales that include signal generation and processing circuitry. U.S. Patent No. 5,886,519 (the '519 patent), U.S. Patent No. 5,841,274 (the '274 patent), and U.S. Patent No. 5,894,678 (the '678 patent) describe electromagnetic induction absolute calipers and electronic tape measures that use electromagnetic induction transducers. U.S. Patent Nos. 10,520,335 (the '335 patent), 10,612,943 (the '943 patent), and 10,775,199 (the '199 patent) disclose improvements in winding configurations useful for increasing the accuracy, robustness, and ease of alignment of electromagnetic inductive encoders. All of the foregoing are incorporated herein by reference in their entireties. As described in these patents and applications, electromagnetic inductive transducers can be manufactured using printed circuit board technology and are largely insensitive to contamination. Summary of the Invention [Problem to be solved by the invention]

[0004] However, these systems may be limited in their ability to provide a particular combination of features desired by a user, such as a combination of small size, high resolution, accuracy, low cost, robustness to dirt, robustness to misalignment, etc. Encoder configurations that provide improved combinations of such features are desired. [Means for solving the problem]

[0005] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] An electromagnetic induction encoder is provided that can be used to measure the relative position between two elements along a measurement axis. In various embodiments, the electromagnetic induction encoder includes a scale, a detector, and a signal processor.

[0007] The scale includes a periodic scale pattern extending along a measurement axis direction and including at least a first type of signal modulating elements. The periodic scale pattern has a spatial wavelength W1. The first type of signal modulating elements include a plurality of conductive plates or loops arranged along the measurement axis direction corresponding to the spatial wavelength W1. The detector is mounted proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern. In various embodiments, the detector includes a magnetic field generating coil and at least one respective set of sensing elements corresponding to respective nominal spatial phases (e.g., two respective sets with spatial phases differing by 90 degrees to provide quadrature signals, or three respective sets with spatial phases differing by 120 degrees to provide three-phase signals). The magnetic field generating coil is fixed to the substrate and surrounds an inner region that is aligned with the active area of ​​the periodic scale pattern of the signal modulating elements during operation. As used herein, the term "surround" can mean completely surrounding or partially surrounding in various embodiments. The only constraint is that the magnetic field generating coils be configured to generate magnetic flux changes in the interior region in response to coil drive signals to support operation according to the principles disclosed and claimed herein. Each sensing element set is disposed along a measuring axis direction and fixed to the substrate. Members of the sensing element set are comprised of conductive loops or conductive loop portions that define sensing element effective areas (EffASEN) corresponding to portions of the sensing elements that are aligned with or overlap the interior region surrounded by the magnetic field generating coils.

[0008] Each set of sensing elements is configured to provide a detection signal responsive to its local contribution to the magnetic flux change provided by an adjacent signal modulating element of the scale pattern, corresponding to a respective nominal spatial phase. The signal processing unit may be operatively connected to the sensing unit to provide a coil drive signal, and is configured to determine the relative position of the sensing unit and the scale pattern based on the detection signal input from the sensing unit.

[0009] In various embodiments of the first type according to the principles disclosed herein (e.g., as shown in Figures 9-13), at least one respective set of sensing elements corresponding to each nominal spatial phase comprises combined features A1, B1, and C1, and further combined with at least one of features D1 or E1, defined as follows:

[0010] A1) It has a plurality of positive polarity loops corresponding to a first winding direction or polarity and an equal number of negative polarity loops corresponding to a second winding direction or polarity opposite to the first winding.

[0011] B1) Each of the positive and negative polarity loops is defined as having a total sensing element effective area EffASEN that is aligned with or overlaps one or more of the internal regions, and an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more internal regions perpendicular to the measurement axis direction, and at least half of the positive and negative polarity loops are configured so that the sensing element average dimension DSENavg=(EffASEN / EffYSEN) along the measurement axis direction is within the range of 0.33*W1±15%.

[0012] C1) The positive polarity loops are configured such that the detector element active areas are disposed in a positive polarity loop defining relationship (positive loop defining relationship for short) with respect to the respective nominal spatial phases of the respective detector element sets, and the negative polarity loops are configured such that the detector element active areas are disposed in a negative polarity loop defining relationship (negative loop defining relationship for short) with respect to the respective nominal spatial phases of the respective detector element sets, wherein the positive loop defining relationship is configured such that a shift ratio of up to half of the total detector element active areas in the plurality of positive polarity loops is shifted along the measurement axis in the first direction by (W1) / 4K relative to the respective nominal spatial phases, a nominally identical shift ratio of all detector element active areas in the plurality of positive polarity loops is shifted along the measurement axis in the opposite direction from the first direction by (W1) / 4K relative to the respective nominal spatial phases, and the two shift ratios of all detector element active areas in the positive polarity loop regions are shifted relative to each other by (W1) / 2K, where K is one of 3, 5, 7, and 9. The negative loop defining relationship comprises a configuration in which a shift ratio of up to half of the total detector element active area of ​​the plurality of negative polarity loops is shifted along the measurement axis in a first direction by (W1) / 4K relative to their respective nominal spatial phases, a nominally identical shift ratio of the total detector element active area of ​​the plurality of negative polarity loops is shifted along the measurement axis in a direction opposite the first direction by (W1) / 4K relative to their respective nominal spatial phases, and the two shift ratios of the total detector element active area of ​​the negative polarity loop regions are shifted relative to each other by (W1) / 2K.

[0013] D1) Each of the positive and negative loops is made up of a sensing element effective area EffASEN whose maximum dimension DSENmax in the measurement axis direction is at most 0.45*W1.

[0014] E1) Each detector element set corresponding to each nominal spatial phase (SETSENPh0) is configured in two parts: a first separation section consisting of the same number of positive and negative polarity loops; and a second separation section nominally aligned with the first separation section along the measurement axis direction and having the same number of positive and negative polarity loops as the first separation section, the first separation section and the second separation section being separated by a gap located along the measurement axis direction between the first separation section and the second separation section, the gap being at least as wide as one of the positive or negative polarity loops along the measurement axis direction, and the effective area of ​​the positive or negative polarity loops of each detector element set is not located within the gap.

[0015] Thereby, each set of detector elements corresponding to each nominal spatial phase (SETSENPh0) is in a practical configuration to provide a spatially filtered detection signal or signals that can be used to reduce or suppress both potential unwanted third order spatial harmonic detection signal components and potential unwanted Kth order spatial harmonic detection signal components that may cause errors in the determined relative position between the detector and the scale pattern.

[0016] As a result of implementing features A1, B1, C1, together with at least one of features D1 and / or E1 as described above, each set of detector elements corresponding to a respective nominal spatial phase is configured to provide a spatially filtered detector signal or signals that can be used to reduce or suppress both potential unwanted third-order spatial harmonic signal components and potential unwanted K-th order spatial harmonic signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. Furthermore, this configuration provides the spatial filtering described above while also providing a novel “layout-friendly” loop arrangement for solving a long-standing, detrimental layout problem, as described in more detail below. In some embodiments of the first type, K=5 may be particularly advantageous. In certain embodiments of the first type, it is advantageous if at least half of the positive and negative polarity loops are configured to provide an average detector element dimension DSENavg that is at least 0.29*W1 and at most 0.31*W1, as described in more detail below with reference to various figures.

[0017] In various embodiments of the first type, each positive or negative polarity loop in each sensing element set, including features A1, B1, C1, and at least one of features D1 and / or E1, may be configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective areas EffASEN of other respective positive or negative polarity loops in each sensing element set. This enables a layout with low manufacturing costs and eliminates harmful loop shape irregularities resulting from layout issues encountered in conventional methods of providing spatial filtering and misalignment error reduction. Prior art techniques have not provided a configuration that combines spatial filtering performance, robustness to misalignment, and a relatively ideal loop shape for the entire sensing element array in an economical manufacturing layout.

[0018] In some embodiments of the first type, at least a first respective set of sensing elements corresponding to a respective nominal spatial phase comprises features A1, B1, C1, and D1, but does not comprise feature E1. In some such embodiments, the first respective set of sensing elements may comprise a first adjacent portion consisting of an equal number of positive and negative polarity loops and a second adjacent portion nominally aligned along the measurement axis with the first adjacent portion and consisting of an equal number of positive and negative polarity loops as the first adjacent portion. The first and second adjacent portions may be located closer to each other along the measurement axis (hence referred to herein as “adjacent portions”) than the width of one of the positive or negative polarity loops, and the respective loops of the first and second adjacent portions closest to each other may have opposite loop polarities. In some such embodiments, the electromagnetic inductive encoder may include at least a second respective set of sensing elements corresponding to a respective nominal spatial phase that differs by 90 degrees from the nominal spatial phase of the first respective set of sensing elements. Each second sensing element set has characteristics A1, B1, C1, D1, and E1. In each second sensing element set, the loops in the first and second nearest isolation portions have the same loop polarity. Each first sensing element set has a first area centroid of its total sensing element active area located along the measurement axis between its first and second nearest isolation portions. Each second sensing element set has a second area centroid of its total sensing element active area located along the measurement axis between its first and second nearest isolation portions. Each first and second sensing element set has its respective first and second area centroids aligned along the measurement axis. This centroid-aligned embodiment provides certain advantages in that it eliminates certain errors due to misalignment of the "pitch" between the sensing element and the scale pattern, while facilitating economical layout and manufacturing.In some such embodiments, each positive or negative polarity loop included in one of the first or second respective sensing element sets is configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective area EffASEN of another respective positive or negative polarity loop included in the same one of the first or second respective sensing element sets.

[0019] As outlined above, in various embodiments including two adjacent or two separated portions, an electromagnetic induction encoder may be configured according to either M1 or M2: M1) a first adjacent (or separated) portion configured to output a first detection signal, a second adjacent (or separated) portion configured to output a second detection signal, and a signal processor configured to determine a relative position between the detection portion and the scale pattern based at least in part on a combination of the first and second signals; or M2) a first adjacent (or separated) portion connected in series with a second adjacent (or separated) portion to form a composite signal, the series connection configured such that the respective signal contributions of the first and second portions are summed in the composite signal, and the signal processor configured to determine a relative position between the detection portion and the scale pattern based at least in part on the composite signal. When adjacent portions are connected in series, the first and second adjacent portions can, in some embodiments, be interpreted as part of a continuous, uninterrupted set of sensing elements.

[0020] In some embodiments of the first type, at least a first respective set of sensing elements corresponding to a respective nominal spatial phase comprises characteristics A1, B1, C1, and E1. In some such embodiments, the first respective set of sensing elements may be configured such that the loops of its first and second separations that are closest to each other have the same loop polarity. Some such embodiments may include at least a second respective set of sensing elements corresponding to a respective nominal spatial phase that differs by 90 degrees from the nominal spatial phase of the first respective set of sensing elements. The second respective set of sensing elements comprises characteristics A1, B1, C1, and E1. In the second respective set of sensing elements, the loops of its first and second separations that are closest to each other have opposite loop polarities. The first respective set of sensing elements has a first area centroid of its total sensing element active area located along the measurement axis between its first and second separations. The second respective sensing element set has a second area centroid of its total sensing element active area located along the measurement axis between its first and second separators. The first and second respective sensing element sets have their respective first and second area centroids aligned along the measurement axis. In some such embodiments, each positive or negative polarity loop included in one of the first or second respective sensing element sets is configured to provide a respective sensing element active area EffASEN that does not overlap with the sensing element active area EffASEN of the other respective positive or negative polarity loop included in the same one of the first or second respective sensing element sets. In some such embodiments, both the first and second respective sensing element sets include both features D1 and E1.

[0021] In some embodiments of the first type, at least a first respective set of sensing elements corresponding to each nominal spatial phase comprises features A1, B1, C1, and at least feature D1, and is configured such that, according to feature C1, multiple pairs of adjacent pairs of positive and negative polarity loop active areas are shifted in a first direction along the measurement axis by (W1) / 4K, and an equal number of pairs of adjacent pairs of positive and negative polarity loop active areas are shifted in a direction opposite to the first direction along the measurement axis by (W1) / 4K. Such a configuration, shifting positive and negative polarity loops in “pairs,” may provide improved accuracy and robustness against misalignment (e.g., compared to shifting positive polarity loops in a first direction and negative polarity loops in the opposite direction). In some such embodiments, it may be advantageous for two respective pairs of adjacent loops at opposite ends of the first respective set of sensing elements to have the positive and negative polarity loop active areas shifted in the same direction along the measurement axis in those two respective pairs (e.g., as outlined with reference to FIG. 12 ).

[0022] Various embodiments of the first type described above may be configured to operate with a "single-track" scale having a single scale pattern track (e.g., as outlined below with reference to Figures 9, 10, 11, and 12), or with a "two-track" scale having two scale pattern tracks (e.g., as outlined below with reference to Figure 13). In various "two-track" embodiments, the scale pattern comprises signal modulating elements arranged in first and second tracks extending along the measuring axis direction, and the field generating coils are configured to surround a portion of a first interior region aligned with the first track and a second interior region aligned with the second track. In such embodiments, each sensing element set comprises features A1, B1, C1, and at least one of features D1 and / or E1, and each comprises a conductive loop extending in the measurement axis direction across the first and second interior area portions to define first and second sensing element active area portions corresponding to portions of the sensing elements that are aligned with or overlapping the first and second interior area portions, respectively, such that the detection signal contribution arising at each conductive loop combines the respective detection signal contributions from its first and second sensing element active area portions.

[0023] In some such dual track embodiments, it may be advantageous to use a configuration in which the scale pattern comprises signal modulating elements or signal modulating element portions periodically arranged in a first track according to a wavelength W1 and signal modulating elements or signal modulating element portions periodically arranged in a second track according to a wavelength W1, the periodic arrangement of the first and second tracks being offset relative to each other by (W1) / 2. The magnetic field generating coils are configured to generate magnetic flux changes of a first polarity in a first internal region portion and magnetic flux changes of a second, opposite polarity in a second internal region portion.

[0024] Of course, the various advantageous features outlined above can be used for multiple respective sets of sensing elements corresponding to multiple respective spatial phases in any encoder (e.g., to provide quadrature or three-phase signals, as outlined above). For example, in some such embodiments, multiple respective sets of sensing elements corresponding to multiple respective spatial phases may each comprise at least features A1, B1, and C1, and at least one of the multiple respective sets of sensing elements may further comprise at least feature E1. Such embodiments may be configured to provide multiple spatially filtered sensing signals that can be used to reduce or suppress potential unwanted third-order spatial harmonic sensing signal components and potential unwanted Kth-order spatial harmonic sensing signal components that may contribute to errors in the determined relative position between the sensing feature and the scale pattern. In some such embodiments, each of the multiple respective sets of sensing elements has an area centroid of its total sensing element active area located within its range along the measurement axis, and the multiple respective sets of sensing elements may be configured so that their respective area centroids are nominally co-located along the measurement axis. Such a configuration can reliably eliminate certain misalignment errors, as described in more detail below. In some such embodiments, each positive or negative polarity loop included in any one of the plurality of respective sensing element sets is configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective areas EffASEN of other respective positive or negative polarity loops included in the same one of the plurality of respective sensing element sets.

[0025] In various embodiments of the second type according to the principles disclosed herein (e.g., as shown in Figures 14-17), at least one respective set of sensing elements corresponding to each nominal spatial phase comprises features A2 and B2 defined as follows:

[0026] A2) It has a plurality of positive polarity loops corresponding to a first winding direction or polarity and an equal number of negative polarity loops corresponding to a second winding direction or polarity opposite to the first winding.

[0027] B2) At least half of the positive polarity loops and at least half of the negative polarity loops are configured such that the detector element active areas are disposed in a predetermined intra-loop shift relationship relative to the respective nominal spatial phases of the respective detector element sets. The intra-loop shift relationship is configured such that, within each such loop, the intra-loop shift ratio of up to half of the detector element active areas is shifted along the measurement axis in the first direction by (W1) / 4K relative to the respective nominal spatial phases, and a nominally identical intra-loop shift ratio of the detector element active areas is shifted along the measurement axis in the opposite direction from the first direction by (W1) / 4K relative to the respective nominal spatial phases. The two intra-loop shift ratios are thereby shifted relative to each other by (W1) / 2K, where K is one of 3, 5, 7, or 9.

[0028] As a result of implementing the above features (A2, B2), the set of detector elements corresponding to each nominal spatial phase is practically configured to provide a spatially filtered detector signal or signals that can be used to reduce or suppress potential unwanted Kth spatial harmonic detector signal components that may cause errors in the determined relative position between the detector and the scale pattern.

[0029] In some embodiments of the second type, for positive and negative polarity loops configured with sensing element active areas arranged in a predetermined intra-loop shift relationship, the intra-loop shift ratio may be nominally half of their sensing element active areas. In some embodiments of the second type, it may be particularly advantageous if all positive and negative polarity loops are configured with their sensing element active areas arranged in a predetermined intra-loop shift relationship.

[0030] In some embodiments of the second type, at least a first respective set of sensing elements is configured according to features A2 and B2, comprising at least a first pair of positive and negative polarity loops configured to have nominally congruent shapes relative to their sensing element active areas, and at least a second pair of positive and negative polarity loops configured to have nominally congruent shapes relative to their sensing element active areas, the congruent shapes in the first and second pairs being nominally mirror images of each other, and the positive and negative polarity loops of the first and second pairs being positioned adjacent to each other. Such a “mirror pair” configuration may, in some embodiments, improve accuracy and / or robustness to certain misalignments. In some such embodiments, a first respective set of sensing elements advantageously comprises at least a first end pair of positive and negative polarity loops configured to have nominally congruent shapes about their sensing element active areas within the first end pair, and at least a second end pair of positive and negative polarity loops configured to have nominally congruent shapes about their sensing element active areas within the second end pair, further configured to have nominally congruent shapes between the first and second end pairs, it being understood that the first and second end pairs are located at the first and second ends of the first respective set of sensing elements.

[0031] In some embodiments of the second type, each sensing element in each sensing element set configured to include features A2 and B2 may have a total sensing element effective area EffASEN that is aligned with or overlaps one or more internal regions and may be defined as having an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more internal regions perpendicular to the measurement axis direction. In various embodiments, it may be advantageous for at least half of such sensing elements to be configured to provide an average sensing element dimension DSENavg=(EffASEN / EffYSEN) along the measurement axis direction that is within the range of 0.33*W1±15%, as described in more detail below with respect to various figures. In various such embodiments, K may be 5, 7, or 9. In such embodiments, each sensing element set configured to include features A2 and B2 is configured to provide a spatially filtered detection signal or signals that can be used to reduce potential unwanted third-order spatial harmonic detection signal components and potential unwanted K-th order spatial harmonic detection signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. In some such embodiments, it may be particularly advantageous for K = 5. In some such embodiments, each positive or negative polarity loop included in each sensing element set configured to include features A2 and B2 may be configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective areas EffASEN of each other positive or negative polarity loop included in the respective sensing element set.

[0032] In some embodiments of the second type, at least a first respective set of sensing elements corresponding to each nominal spatial phase is configured according to features A2 and B2 and is characterized by a two-part configuration. The two-part configuration includes a first separation section consisting of an equal number of positive and negative polarity loops, and a second separation section nominally aligned along the measurement axis with the first separation section and consisting of the same number of positive and negative polarity loops as the first separation section. The first and second separation sections are separated by a gap located along the measurement axis between the first and second separation sections, the gap being at least as wide as one of the positive or negative polarity loops along the measurement axis, and neither the active area of ​​the positive or negative polarity loops of each set of sensing elements is located within the gap. In some such embodiments, the first respective set of sensing elements is configured such that the loops in its first and second separation sections that are closest to each other have the same loop polarity. In some such embodiments, the electromagnetic induction encoder further includes at least a second respective set of sensing elements corresponding to a respective nominal spatial phase that differs by 90 degrees from the nominal spatial phase of the first respective set of sensing elements, the second respective set of sensing elements being configured according to features A2 and B2, resulting in a two-part configuration. The two-part configuration is comprised of either two “adjacent portions” in some embodiments or two “separate portions” in other examples. The following description describes both cases, with parenthetical references to alternative characteristics related to “separate portions.” The two-part configuration may include a first adjacent portion (separate portion) comprised of an equal number of positive and negative polarity loops, and a second adjacent portion (separate portion) nominally aligned with the first adjacent portion (separate portion) along the measurement axis and comprised of an equal number of positive and negative polarity loops as the first adjacent portion (separate portion). The first and second adjacent portions (separate portions) are located closer to each other (farther from each other) along the measurement axis direction than the width of one of the positive or negative polarity loops, and the loops of the first and second adjacent portions (separate portions) that are closest to each other have opposite loop polarities.Each first sensing element set has a first area centroid of its total sensing element active area located between its first and second separating portions along the measurement axis, and each second sensing element set has a second area centroid of its total sensing element active area located between its first and second adjacent separating portions along the measurement axis. In some such embodiments, each first and second sensing element set may have its respective first and second area centroids aligned along the measurement axis. This aligned centroid embodiment may provide certain advantages in terms of eliminating certain errors due to misalignment of the “pitch” between the sensing element and the scale pattern, while facilitating economical layout and manufacturing. In some such embodiments, each positive or negative polarity loop included in one of the first or second sensing element sets is configured to provide a respective sensing element active area EffASEN that does not overlap with the sensing element active area EffASEN of the other respective positive or negative polarity loop included in the same one of the first or second sensing element sets.

[0033] As outlined above, in various embodiments of the second type including two adjacent or two separated portions, an electromagnetic induction encoder may be configured according to either M1 or M2. M1) A first adjacent (or separated) portion is configured to output a first detection signal, a second adjacent (or separated) portion is configured to output a second detection signal, and a signal processor is configured to determine a relative position between the detection portion and the scale pattern based at least in part on a combination of the first and second signals. Or, M2) The first adjacent (or separated) portion is connected in series with the second adjacent (or separated) portion to form a composite signal, the series connection being configured such that the respective signal contributions of the first and second portions are added in the composite signal, and the signal processor is configured to determine a relative position between the detection portion and the scale pattern based at least in part on the composite signal. When adjacent portions are connected in series, the first and second adjacent portions can, in some embodiments, be interpreted as part of a continuous, uninterrupted set of sensing elements.

[0034] Various embodiments of the second type described above may be configured to operate with a “single-track” scale having a single scale pattern track (e.g., as outlined below with reference to Figures 14, 15, and 16), or a “dual-track” scale having two scale pattern tracks (e.g., as outlined below with reference to Figure 17). In various “dual-track” second-type embodiments, the scale pattern comprises signal modulating elements arranged in first and second tracks extending along the measurement axis direction, and the field generating coil is configured to surround a first internal region portion aligned with the first track and a second internal region portion aligned with the second track. In such embodiments, each set of sensing elements may comprise conductive loops having features A2 and B2, respectively, extending in the measurement axis direction across the first and second internal region portions to define first and second sensing element active area portions corresponding to portions of the sensing elements aligned with or overlapping the first and second internal region portions, respectively. The sense signal contribution produced in each conductive loop combines the sense signal contributions from its first and second sensing element active area portions, respectively.

[0035] In some such two-track second type embodiments, it may be advantageous to use a configuration in which the scale pattern comprises signal modulating elements or signal modulating element portions periodically arranged in a first track according to a wavelength W1 and signal modulating elements or signal modulating element portions periodically arranged in a second track according to a wavelength W1, the periodic arrangement of the first and second tracks being offset relative to each other by (W1) / 2. The magnetic field generating coils are configured to generate magnetic flux changes of a first polarity in the first internal region portion and to generate magnetic flux changes of a second, opposite polarity in the second internal region portion.

[0036] As noted above and described in more detail below with respect to various figures, many different embodiments of the second type may be configured such that each conductive loop or conductive loop portion included in a respective sensing element set having features A2 and B2 has a respective sensing element effective area EffASEN that does not overlap with other respective sensing element effective areas EffASEN of other conductive loops or conductive loop portions included in that same respective sensing element set. This is believed to be particularly advantageous in some embodiments of the second type for facilitating economical layout and manufacturing, while at the same time providing a relatively ideal combination of a spatially filtered detection signal and suppression of misalignment errors, as outlined above and described in more detail below. No prior art configuration offers a comparable combination of functionality and performance.

[0037] Of course, any of the second type of embodiments outlined above can be used with a plurality of respective sets of sensing elements corresponding to a plurality of respective spatial phases in any encoder, as outlined above (e.g., to provide quadrature or three-phase signals). In such embodiments, each of the plurality of respective sets of sensing elements corresponding to a plurality of respective spatial phases is configured to include features A2) and B2) to provide a spatially filtered detected signal that can be used to reduce or suppress potential unwanted Kth spatial harmonic detected signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. In some such embodiments, each of the plurality of respective sets of sensing elements has an area centroid of its total sensing element active area located within its range along the measurement axis, and the plurality of respective sets of sensing elements are configured such that their respective area centroids are aligned at the same location along the measurement axis. This can be advantageous in reducing certain misalignment errors that may otherwise occur, as outlined above and described in more detail below. As noted above, in some such embodiments, each conductive loop or conductive loop portion included in a respective sensing element set having features A2 and B2 may have a respective sensing element effective area EffASEN that does not overlap with other respective sensing element effective areas EffASEN of other conductive loops or conductive loop portions included in the same respective sensing element set. In some such embodiments, each sensing element in the plurality of respective sensing element sets is defined as having a total sensing element effective area EffASEN that is aligned with or overlapping one or more interior regions and having an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more interior regions perpendicular to the measuring axis direction, and at least half of the sensing elements in the plurality of respective sensing element sets are configured such that the average sensing element dimension DSENavg=(EffASEN / EffYSEN) along the measuring axis direction is within the range of 0.33*W1±15%.The electromagnetic induction encoder is thereby configured to provide a plurality of spatially filtered detection signals that can be used to reduce or suppress potential unwanted third order spatial harmonic detection signal components and potential unwanted Kth order spatial harmonic detection signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 is an exploded isometric view of a hand tool type vernier caliper that utilizes an electromagnetic induction encoder including a detector and a scale. [Figure 2] FIG. 1 is a plan view diagrammatically illustrating certain features of a representative prior art electromagnetic inductive encoder, presented as background information related to various principles disclosed herein. [Figure 3] FIG. 2 is a plan view of an embodiment of a detector and scale pattern usable in an electromagnetic inductive encoder such as that shown in FIG. 1 , showing signal modulating elements according to principles disclosed herein in combination with known “less desirable” sensing elements, along with various dimensions that may characterize their characteristics according to principles disclosed herein. [Figure 4] FIG. 4 is an enlarged isometric view of a portion of the sensing element and scale pattern shown in FIG. 3, including a qualitative representation of magnetic flux and flux coupling characteristics that may be associated with the operation of a signal modulating element in an electromagnetic inductive encoder. [Figure 5A] 4A-4C are plan views schematically illustrating certain aspects of embodiments of respective signal modulating and sensing elements similar to those shown in FIG. 3, including additional examples of certain exemplary dimensions that may characterize those features in accordance with the principles disclosed herein. [Figure 5B] 4A-4C are plan views schematically illustrating certain aspects of embodiments of respective signal modulating and sensing elements similar to those shown in FIG. 3, including additional examples of certain exemplary dimensions that may characterize those features in accordance with the principles disclosed herein. [Figure 6]9-12 and 13 are plan views showing various embodiments of sensing elements and scale patterns suitable for use in the detectors and scale patterns of an electromagnetic induction encoder such as that shown in FIG. 1, along with examples of various dimensions that may characterize their features. [Figure 7] 9-12 and 13 are plan views showing various embodiments of sensing elements and scale patterns suitable for use in the detectors and scale patterns of an electromagnetic induction encoder such as that shown in FIG. 1, along with examples of various dimensions that may characterize their features. [Figure 8] 9-12 and 13 are plan views showing various embodiments of sensing elements and scale patterns suitable for use in the detectors and scale patterns of an electromagnetic induction encoder such as that shown in FIG. 1, along with examples of various dimensions that may characterize their features. [Figure 9] FIG. 2 is a plan view showing a particular aspect of a first exemplary configuration of a sensing element set configured according to a first type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , a first set of sensing elements corresponding to a first spatial phase, along with a first compatible magnetic field generating coil and scale pattern, including various dimensions characterizing the sensing element configuration according to the principles disclosed herein. [Figure 10] FIG. 10 is a plan view showing a particular side of a second set of sensing elements corresponding to a second spatial phase configured similarly to the first sensing elements shown in FIG. 9 superimposed on a ghosted representation of the first set of sensing elements shown in FIG. 9, illustrating an operating quadrature configuration in which the spatial phases of the first and second sets of sensing elements differ by 90 degrees. [Figure 11A]11A is a plan view showing a side view of a second sensing element set corresponding to a second spatial phase, which is a second exemplary configuration of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein, along with the first sensing element set shown in FIG. 9. For illustrative purposes, the first and second sensing element sets are offset from each other along the vertical direction in FIG. 11A to better illustrate their individual characteristics and their relative alignment along the measurement axis direction in an operational quadrature configuration in which the spatial phases of the first and second sensing element sets differ by 90 degrees. [Figure 11B] 11B is a plan view showing a particular side view of a first sensing element set corresponding to a first spatial phase, along with the second sensing element set shown in FIG. 11A, which is a third exemplary configuration of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein. For illustrative purposes, the first and second sensing element sets are offset from each other along the vertical direction in FIG. 11B to better illustrate their individual characteristics and their relative alignment along the measurement axis direction in an operational quadrature configuration in which the spatial phases of the first and second sensing element sets differ by 90 degrees. [Figure 12] 12A and 12B are plan views illustrating certain side views of first and second sets of sensing elements corresponding to their respective spatial phases, which are fourth and fifth exemplary configurations of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein. For illustrative purposes, the first and second sets are offset from each other along the vertical direction in FIG. 12 to better illustrate their individual characteristics and their relative alignment along the measurement axis direction in an operational quadrature configuration in which the spatial phases of the first and second sets differ by 90 degrees. [Figure 13]FIG. 10 is a plan view showing a sixth exemplary configuration of a sensing element set configured according to a first type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , illustrating a particular aspect of a first sensing element set corresponding to a first spatial phase, along with a second compatible magnetic field generating coil and scale pattern, including various dimensions characterizing the sensing element configuration according to the principles disclosed herein. [Figure 14] 9 is a plan view showing a side view of a first exemplary configuration of a first set of sensing elements configured according to a second type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , the first set of sensing elements corresponding to a first spatial phase, along with the first compatible magnetic field generating coil and scale pattern shown in FIG. 9 , including various dimensions characterizing the sensing element configuration according to the principles disclosed herein. [Figure 15] 14A and 14B are plan views showing a particular aspect of a first set of sensing elements corresponding to a first spatial phase, which is a second exemplary configuration of sensing element sets configured according to a second type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , along with the first compatible magnetic field generating coil and scale pattern shown in FIGS. 9 and 14A, including various dimensions characterizing the sensing element configuration according to the principles disclosed herein. [Figure 16]16 is a plan view showing a side view of a second sensing element set corresponding to a second spatial phase, which is a third exemplary configuration of sensing element sets configured according to the second type of predetermined relationship principle disclosed herein, along with the first sensing element set shown in FIG. 15. For illustrative purposes, the first and second sensing element sets are offset from each other along the vertical direction in FIG. 16 to better illustrate their individual characteristics and their relative alignment along the measurement axis direction in an operational quadrature configuration in which the spatial phases of the first and second sensing element sets differ by 90 degrees. [Figure 17] 13 is a plan view showing a particular aspect of a first set of sensing elements corresponding to a first spatial phase, along with the second compatible magnetic field generating coil and scale pattern shown in FIG. 13, which is a fourth exemplary configuration of sensing element sets configured according to the second type of predetermined relationship principles disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1, including various dimensions characterizing the sensing element configuration according to the principles disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0039] FIG. 1 is an exploded isometric view of a hand tool caliper 100 including a scale member 172 and a slider assembly 120. The scale member 172 may comprise a main scale of a generally rectangular cross section including a scale 170 disposed within a groove. The slider assembly 120 may include a base 140, an electronic assembly 160, and a cover 150, which are described in more detail below. The electronic assembly 160 may include a sensing portion 167 and a signal processing portion 166 disposed on a substrate 162. An elastic seal (not shown) may be compressed between the cover 150 and the substrate 162 to exclude contaminants from the electronic circuitry and connections. The scale 170, sensing portion 167, and signal processing portion 166 cooperate to provide an electromagnetic induction encoder usable to measure the relative position between two elements (e.g., between the scale member 172 and the slider assembly 120) along a measurement axis direction MA.

[0040] In various embodiments, scale 170 extends along a measurement axis direction MA (e.g., corresponding to the x-axis direction) and includes a signal modulation scale pattern 180 including signal modulating elements SME fabricated on a scale substrate (e.g., using known printed circuit fabrication methods). In various embodiments shown herein, signal modulation scale pattern 180 may alternatively be referred to as a periodic scale pattern 180, which is shown in FIG. 1 as having a spatial wavelength W1. In the illustrated embodiment, a cover layer 174 of a known type (e.g., 100 μm thick) covers scale 170 (as shown cut away in FIG. 1).

[0041] In various embodiments, the mechanical structure and operation of caliper 100 may be similar to that of certain conventional electronic calipers, such as those described in commonly assigned U.S. Pat. No. 5,901,458, U.S. Pat. No. 6,400,138, and / or U.S. Reissue Pat. No. 37490 (each of which is incorporated by reference herein in its entirety). Jaws 176 and 178 near a first end of scale member 172 and movable jaws 146 and 148 on slider assembly 120 are used to measure a dimension of an object in a known manner. The measured dimension can be displayed on a digital display 158 mounted within cover 150 of electronic assembly 160. Cover 150 may also include an on / off switch 154 and other optional control buttons, as needed, to activate circuits or elements contained in electronic assembly 160. The base 140 of the slider assembly 120 may include various known elements configured to guide the slider assembly 120 along the mating edge of the scale member 172 to ensure proper alignment for measurement while moving the slider assembly 120 relative to the scale 170.

[0042] 1 , the detection unit 167 may include a magnetic field generating coil FGC and a set of sensing elements SETSEN arranged along the measurement axis direction MA. In one specific illustrative example, the detection unit 167 may be arranged parallel to and facing the scale 170, and the front surface of the detection unit 167 facing the scale 170 may be separated from the scale 170 (and / or the scale pattern 180) by a gap of approximately 0.5 mm along the Z-axis direction. The front surface of the detection unit 167 (e.g., its constituent conductors) may be covered with an insulating coating. The structure and operation of the magnetic field generating coil FGC and the set of sensing elements SETSEN are described in more detail below.

[0043] It will be appreciated that the caliper 100 shown in FIG. 1 is one of a variety of applications that typically implement electromagnetic inductive encoders, which have evolved over the years to provide a relatively optimized combination of compact size, low-power operation (e.g., for long battery life), high-resolution and high-precision measurement, low cost, robustness to contamination, etc. Other applications that are perhaps even more challenging in terms of advanced accuracy improvements, cost-effective design, and manufacture include medium- and high-precision digital “dial” indicators (which provide, for example, accuracies on the order of 10 micrometers and 1 micrometer, respectively). Even modest improvements in any of these factors in any of these applications are highly desirable, but difficult to achieve, especially in light of the design constraints imposed to achieve commercial success in various applications. The principles disclosed and claimed herein provide improvements in many of these factors for a variety of applications.

[0044] FIG. 2 is a plan view diagrammatically illustrating certain features of a representative prior art electromagnetic inductive encoder shown in the '389 patent, presented as background information related to various principles disclosed elsewhere herein. FIG. 2 further includes reference numerals to indicate equivalent reference numerals or symbols used to indicate equivalent elements in other figures included herein. In the following abbreviated description based on the disclosure of the '389 patent, equivalent reference numerals in other figures of the present disclosure are shown in parentheses following the original reference numerals from the '389 patent. A complete description of prior art FIG. 2 can be found in the '389 patent. Therefore, only the abbreviated description, including teachings from the '389 patent relevant to the present disclosure, is included herein. To the best of the inventor's knowledge, the teachings outlined below with reference to FIG. 2 represent conventional theory and conventional design techniques known in the art and / or used in commercially available electromagnetic inductive encoders.

[0045] As disclosed in the '389 patent, a transducer such as that shown in FIG. 2 includes at least two substantially coplanar paths of wire or winding. The transmitter winding 102 (FGC) forms a large planar loop. The receiver winding 104 (SETSEN), which is substantially in the same plane as the transmitter winding 102, is arranged in one direction, as indicated by the arrows, in a zigzag or sinusoidal pattern, and then the winding is arranged in the opposite direction, as indicated by the arrows, across itself to form loops 106 (SEN+) and 108 (SEN−), which are alternately arranged between each other. As a result, each of the alternating loops 106 (SEN+) and 108 (SEN−) of the receiver winding 104 (SETSEN) has a different winding direction or polarity compared to adjacent loops. By applying an alternating (varying) current to the transmitter winding 102 (FGC), the transmitter winding generates a time-varying magnetic field that penetrates the loops 106 (SEN+) and 108 (SEN-) of the receiver winding 104 (SETSEN).

[0046] When a conductive object (e.g., a scale or scale pattern 112 (180) (segments of which are outlined in FIG. 2 by alternating long-dotted and short-dotted edges) including conductive plates 114 (SME) (some of which are outlined using dashed lines on the scale pattern 112 in FIG. 2) is moved near the transducer, the changing magnetic field generated by the transmitter winding 102 (FGC) induces eddy currents in the conductive object, which in turn causes a magnetic field to arise from the conductive object that cancels the fluctuations in the transmitter magnetic field. As a result, the magnetic flux received by the receiver winding 104 (SETSEN) is changed or disturbed, causing the receiver winding to output a non-zero EMF signal (voltage) at the output terminals V+ and V− of the receiver winding 104, which changes polarity as the conductive object moves between the positive polarity “+” loop 106 (SEN+) and the negative polarity “−” loop 108 (SEN−).

[0047] In this prior art example, the distance between the positions of two loops of the same polarity (e.g., between the position of loop 106 (SEN+) and the position of the next loop 106 (SEN+)) is defined as the transducer pitch or wavelength 110 (W1). It can thus be seen that each loop 106 (SEN+) and / or 108 (SEN−) has a length or maximum dimension of 0.5*W1 along the measurement axis direction 300. When the aforementioned conductive object (e.g., conductive plate 114 (SME)) is proximate to the receiver winding 104 (SETSEN) and continuously changes position along the measurement axis 300 (MA), the AC amplitude of the signal output from the receiver winding (SETSEN) continuously and periodically changes with the wavelength 110 (W1) due to the periodic polarity changes of the loops 106 (SEN) and 108 (SEN) and the localized disturbances in the transmit magnetic field caused by the conductive object (e.g., conductive plate 114 (SME)).

[0048] The '389 patent emphasizes that when the conductive object (e.g., the conductive plate 114 (SME)) is much smaller or larger than the loops 106 and / or 108 (SEN+, SEN−), the amplitude of the signal output is weak and it is difficult to obtain high accuracy. When the conductive object (e.g., the conductive plate 114 (SME)) has a length equal to approximately half the wavelength 110 (W1) (i.e., when the object can be positioned exactly in line with the loops 106 or 108 (SEN+ or SEN−)), the signal output has a large amplitude and is therefore most sensitive to the position of the conductive object. Therefore, the present disclosure (described in the '389 patent) preferably uses a conductive object (e.g., the conductive plate 114 (SME)) having a length (along the x-axis direction) equal to half the wavelength 110 (W1).

[0049] The transmitter winding 102 and receiver winding 104 (SETSEN) shown in FIG. 2 and described above are an example of a prior art embodiment of an element designated herein as a detector (e.g., detector 167 shown in FIG. 1), and the scale or scale pattern 112 (180) is an example of a prior art embodiment of an element designated herein as a scale pattern (e.g., scale pattern 180 shown in FIG. 1).

[0050] FIG. 3 is a plan view of an embodiment of a sensing portion 367 and scale pattern 380 usable in an electromagnetic induction encoder such as that shown in FIG. 1 , showing a signal modulating element SME according to principles disclosed herein combined with a known, conventional, "less desirable" sensing element SEN for clarity of explanation. FIG. 3 also introduces various dimensions that may characterize the signal modulating element SME and sensing element SEN according to principles disclosed herein. More preferred sizes and shapes of sensing elements SEN according to principles disclosed herein are described in more detail below with reference to FIGS. 6, 7, and 8. Alternative desirable configurations and / or predetermined relationships for determining the position and / or shape of sensing elements SEN according to principles disclosed herein are further described below with reference to FIGS. 9-13 and 14-17.

[0051] The various features of detector 367 and scale pattern 380 are configured to satisfy various design principles disclosed and claimed herein, particularly with respect to signal modulating element SME. It is understood that some numbered components 3XX in Figure 3 may correspond to and / or provide similar operation or functionality to similarly numbered components 1XX in Figures 1 and / or 2 (e.g., detector 367 provides similar operation or functionality as detector 167) and may be understood similarly unless otherwise indicated.

[0052] FIG. 3 can be considered partially representational and partially schematic. Enlarged portions of the sensing portion 367 and scale pattern 380 are shown at the bottom of FIG. 3. In FIG. 3, various elements described below are represented by their shapes or outlines and are shown superimposed on one another to emphasize certain geometric relationships. It will be understood that various elements may reside on different fabrication layers located in different planes along the z-axis direction, as needed, to provide various operating gaps and / or insulating layers, as will be apparent to those skilled in the art based on the following description and the cited references. Throughout the figures of this disclosure, the illustrated x-axis, y-axis, and / or z-axis dimensions of one or more elements may be exaggerated for clarity, but it will be understood that they are not intended to contradict the various dimensional design principles and relationships disclosed and claimed herein.

[0053] The depicted portion of the scale pattern 380 includes a first type of signal modulating element SME, shown with dotted fill and dashed outline. The periodic scale pattern 380 has a spatial wavelength W1. In this embodiment, the first type of signal modulating element SME comprises a plurality of conductive plates (e.g., formed by regions fabricated on a printed circuit board or by raised regions extending from a conductive substrate). However, in other embodiments, they may include a plurality of conductive loops (e.g., formed by traces on a printed circuit board), as described in more detail below. In either case, they are arranged along a measuring axis direction MA, which corresponds to the spatial wavelength W1. The scale pattern 380 is typically implemented on a scale (e.g., the scale 170 shown in FIG. 1). In the example shown in FIG. 3, the y-direction ends of most of the signal modulating elements SME are hidden beneath first and second extensions EP1 and EP2 of the field generating coil FGC (e.g., as described in the '335, '943, and '199 patents). It will be appreciated that, as shown in Figure 1, the scale pattern 380 moves relative to the detector portion 367 during operation.

[0054] 3, the scale pattern 380 has a nominal scale pattern width dimension NSPWD along the y-axis direction and comprises generally rectangular signal modulating elements SME arranged periodically (e.g., corresponding to the x-axis direction) along the measurement axis direction MA. However, more generally, the scale pattern 380 can include a variety of alternative spatial modulation patterns including alternative signal modulating element configurations, provided that the pattern has spatial characteristics that vary as a function of position along the x-axis direction to provide position-dependent detection signals (also referred to in some embodiments as detection signal components) arising within sensing elements SEN (e.g., SEN14) of sensing element sets SETSEN in the detection portion 367.

[0055] In various embodiments, the sensing portion 367 is mounted proximate the scale pattern 380 and configured to move along the measurement axis direction MA relative to the scale pattern 380. As will be appreciated by those skilled in the art, the sensing portion includes a magnetic field generating coil FGC and a set of sensing elements SETSEN, which can assume a variety of alternative configurations used in various embodiments in combination with various corresponding signal processing schemes. FIG. 3 shows a single representative set of sensing elements SEN1-SEN24, which in this embodiment comprise sensing loop elements (alternatively referred to as sensing coil elements or sensing winding elements) connected in series. In this embodiment, adjacent loop elements are connected by a configuration of conductors on various layers of a PCB (e.g., connected by feedthroughs) and are connected to have opposite winding polarities according to known methods (e.g., as shown in FIG. 4). That is, if a first loop responds to a change in the magnetic field with a sense signal contribution of positive polarity, the adjacent loop responds with a sense signal contribution of negative polarity. A loop having a sense signal contribution of positive polarity may be referred to herein as a SEN+ sensing element, and a loop having a sense signal contribution of negative polarity may be referred to as a SEN− sensing element in various contexts herein. In this embodiment, the sensing elements are connected in series so that their detection signals or signal contributions are added, and the "added" detection signals are output to a signal processing unit (not shown) on detection signal output connections SDS1 and SDS2.

[0056] While FIG. 3 shows a single set of sensing elements to avoid visual confusion, those skilled in the art will appreciate that in various embodiments it may be advantageous to configure the detector to provide one or more additional sets of sensing elements (e.g., similar to SETSEN) at different spatial phase locations (e.g., to provide orthogonal signals). However, it should be understood that the sensing element configurations described herein are exemplary only and not limiting. By way of example, individual sensing element loops may, in some embodiments, output individual signals to corresponding signal processors, as disclosed, for example, in U.S. Pat. No. 9,958,294. More generally, various known sensing element configurations may be used in various embodiments in combination with the principles disclosed and claimed herein for use in combination with various known scale patterns and signal processing schemes.

[0057] The various members of the set of sensing elements SETSEN and the set of field generating coils FGC may be fixed on a substrate (e.g., substrate 162 of FIG. 1 ). The field generating coils FGC can be described as surrounding an interior region INTA having a nominal coil area length dimension NCALD along the x-axis direction and a nominal coil area width dimension of approximately YSEP along the y-axis direction. The interior region INTA is aligned with the periodic scale pattern 380 of the signal modulating element SME during operation, approximately as shown. In the illustrated embodiment, the field generating coils FGC include a single winding surrounding the interior region INTA. However, in various other embodiments, the field generating coils FGC can include multiple turns and / or be serpentine, operatively surrounding (e.g., operatively partially surrounding) the interior region INTA aligned with the scale pattern 380, as well as operatively surrounding (e.g., operatively partially surrounding) other interior regions aligned with scale tracks containing other scale patterns, as disclosed in the references. In any event, in operation, the field generating coil FGC generates magnetic flux changes in the interior region INTA in response to a coil drive signal. In the illustrated embodiment, a first connection portion CP1 and a second connection portion CP2 can be used to couple a coil drive signal from a signal processor (e.g., signal processor 166 of FIG. 1) to the field generating coil FGC.

[0058] The sensing element set SETSEN (e.g., a set of sensing elements SEN1-SEN24) is arranged along an x-axis direction (e.g., corresponding to the measurement axis direction MA) and fixed on a substrate (e.g., substrate 162 in FIG. 1). As shown in FIG. 3, the members of the sensing element set are composed of conductive loops or conductive loop portions (e.g., SEN1-SEN24) that define a sensing element effective area EffASEN corresponding to the portion of the sensing element that is aligned with or overlaps the internal region INTA surrounded by the field generating coil FGC (i.e., the portion of the sensing element that is aligned with or overlaps the dimension YSEP of INTA). In various embodiments, the sensing element effective area EffASEN that is aligned with or overlaps the internal region INTA can be described as having an effective y-axis dimension EffYSEN along the y-axis direction, which is orthogonal to the measurement axis direction, and a maximum dimension DsENmax along the measurement axis direction (x-axis direction). In the particular embodiment shown in FIG. 3, the effective y-axis dimension EffYSEN is equal to YSEP. This is because each of the sensing elements SEN has a maximum sensing element dimension YSENMAX along the y-axis direction that exceeds YSEP, and therefore its effective area EffASEN spans the entire dimension YSEP. The maximum dimension DSENmax in the measuring axis direction is nominally 0.5*W1. However, these features are specific to this embodiment and are not limiting, and may be optional (or undesirable) in various embodiments, as described in more detail below with reference to Figures 5B, 6, 7, and 8.

[0059] It is useful to further characterize the detector element effective area, EffASEN, by the average detector element dimension along the measurement axis, SENavg=(EffASEN / EffYSEN). In the particular embodiment shown in Figure 3, the detector element effective area, EffASEN, has parallel sides perpendicular to the x-axis direction, so that DSENavg is equal to DSENmax. However, this need not be the case in all embodiments, as will be explained in more detail below with reference to Figures 5B, 6, 7, and 8.

[0060] The sensing elements of the sensing element set SETSEN are configured to provide detection signals responsive to local influences on magnetic flux changes provided by adjacent signal modulating elements SME (e.g., one or more signal modulating elements SME) of the scale pattern 380. A signal processing unit (e.g., signal processing unit 166 of FIG. 1 ) may be configured to determine the position of the sensing element set SETSEN relative to the scale pattern 380 based on the detection signals input from the detection unit 367. In general, the field generating coil FGC and the sensing element set SETSEN, etc., may operate according to known principles (e.g., electromagnetic induction encoders) as described in the references.

[0061] In various embodiments, the field generating coil FGC and the sensing element SEN are insulated from one another (e.g., by being disposed on different layers of a printed circuit board). In one such embodiment, the maximum y-axis sensing element dimension YSENMAX of the sensing element SEN is advantageously greater than the nominal coil area width dimension YSEP and extends beyond the inner edge of the extension EP1 or EP2 by an amount defined as the overlap dimension. Furthermore, the field generating coil FGC may be advantageously configured such that the trace widths of the extensions EP1 and EP2 along the y-axis direction are greater than the corresponding overlap dimensions. In various embodiments, the extensions EP1 and EP2 may be fabricated on a first layer of the printed circuit board, and the sensing element SEN may include conductive loops fabricated in one or more layers of the printed circuit board, including layers different from the first layer, at least near the overlap dimension. However, such embodiments are illustrative and not limiting, as further described below.

[0062] As previously indicated, in some embodiments, the magnetic field generating coil FGC can include one or more conductive traces fabricated on a printed circuit board, and the sensing element SEN of the sensing element set SETSEN can include a magnetic flux sensing loop or loop portion formed by the conductive traces fabricated on the printed circuit board. As discussed above with respect to FIG. 1 , in various embodiments, the sensing unit 367 can be included in various types of measuring instruments (e.g., calipers, micrometers, gauges, linear scales, etc.). For example, the sensing unit 367 can be fixed to a sliding member, and the scale pattern 380 can be fixed to a handle or main scale whose measurement axis coincides with the x-axis direction. In such a configuration, the sliding member is movably mounted on a beam or girder member and can move along the measurement axis MA in a plane extending along the x-axis and y-axis directions, with the z-axis direction perpendicular to the plane.

[0063] The enlarged cross-section of the sensing portion 367 and scale pattern 380 shown at the bottom of FIG. 3 illustrates three exemplary sensing elements SEN14, SEN15, and SEN16 of the sensing element set SETSEN, bounded by portions of the magnetic field generating coil FGC, and two exemplary signal modulating elements SME. In this embodiment, the sensing elements may be formed by traces fabricated on the first and second layers of a circuit board with a layer of insulation between them. "First layer" traces are shown as solid lines, and "second layer" traces are shown as dashed lines. Small arrows indicate the direction of current induced in the traces by changing magnetic fields emanating from the magnetic field generating coil FGC. It can be seen that sensing element SEN14 can be characterized as a "SEN+" positive polarity loop due to its associated current direction, and adjacent sensing element SEN15 can be characterized as a "SEN-" negative polarity loop due to its associated "opposite polarity" current direction. The next adjacent sensing element SEN16 may again be characterized as a "SEN+" positive polarity loop, and so on.

[0064] DSME is the average dimension of the "effective area" EffRSME of the (first type) signal modulating element SME along the measurement axis direction MA. The effective area EffRSME of the signal modulating element SME here aligns with or overlaps with the y-axis dimension of the interior region INTA. The effective area EffRSME produces the primary signal modulating effect in the sensing element SEN. In the example shown in FIG. 3, it can be seen that this is the portion of the signal modulating element SME that coincides with the span of the dimension YSEP along the y-axis direction. In various embodiments, the average dimension DSME of the signal modulating element SME can be considered to be the area of ​​the effective area EffRSME of the signal modulating element SME divided by the y-axis dimension of the effective area EffRSME. Further examples of dimensions DSME for other configurations of the signal modulating element SME are shown in FIGS. 5A, 5B, 6, 7, and 8.

[0065] As outlined above with reference to FIG. 2, it is conventional for sensing elements, such as sensing element SEN, to have a maximum dimension D SEN max along the measuring axis that is 0.5*W l. Such dimensions may be advantageous in various embodiments. Furthermore, as previously described with reference to FIG. 2, it is also conventional for signal modulating elements, such as signal modulating element SME, to have an average width dimension D S ME that is 0.5*W l. Contrary to the conventional prior art design approach described above, the present inventors have discovered that certain performance characteristics may be improved when signal modulating element S ME is configured to have an average width dimension D S ME that is significantly greater than 0.5*W l, as shown in FIG. 3. For example, in some embodiments, it may be advantageous for D S ME to be at least 0.55*W l and at most 0.8*D SEN. In some such embodiments, it may be advantageous for D S ME to be at least 0.66*W l, or 0.7*W l or greater, as will be explained below with reference to FIG. 4.

[0066] Furthermore, the inventors have further discovered that, to mitigate certain errors that would otherwise appear, for highest accuracy in various applications, it is most desirable to use unconventional sensing elements SEN in combination with unconventional sensing elements SEN configured such that their sensing element average dimension DSENavg is in a range significantly less than 0.5*W1. For example, in various embodiments, it is desirable for the sensing element average dimension DSENavg to be at least 0.285*W1 and at most 0.315*W1. This aspect of the invention is described in more detail below with reference to FIGS. 6, 7, and 8. This combination of unconventional features provides advantageous detection signal characteristics (e.g., better signal-to-noise (S / N) ratio and / or reduced error components in the detection signal) compared to configurations according to prior art design principles.

[0067] Figure 4 is an enlarged isometric view of a portion of the sensing portion 367 and scale pattern 380 shown in Figure 3, including a qualitative representation of magnetic flux and flux coupling characteristics that may be associated with the operation of the signal modulating element SME in such an electromagnetic inductive encoder. Figure 4 illustrates various considerations related to why, in various embodiments, it may be advantageous for the signal modulating element SME to be configured to have an average width dimension DSM that is at least 0.55*W1 and at most 0.8*W1.

[0068] FIG. 4 illustrates the response of the signal modulation element SME to the generated changing magnetic field G M F provided by the field generating coil FGC, as outlined above. As shown in FIG. 4, a coil drive signal current I gen applied to the field generating coil FGC generates a changing magnetic field G M F that inductively couples to the signal modulation element SME. The signal modulation element SME is shown schematically in FIG. 4 as a conductive loop, and in response to the coupled changing magnetic field G M F, an induced current I ind is generated within the signal modulation element SME, which generates an induced magnetic field represented by magnetic flux lines (magnetic flux lines including arrows in FIG. 4). The illustrated magnetic flux lines represent a central magnetic flux C F represented by central magnetic flux line C F L and peripheral magnetic flux M F represented by closed peripheral magnetic flux lines M F L1-M F L3 shown surrounding the conductive loop of the signal modulation element SME.

[0069] Generally speaking, it will be understood that the sensing elements of sensing element set SETSEN generate signals (or signal contributions) responsive to induced magnetic flux changes, as outlined above. In particular, the generated signal generates a signal contribution or signal component, represented as a current Isense, in sensing element SEN14 of FIG. 4 in response to the amount of magnetic flux effectively coupled through its inner loop area. As shown in FIG. 4 , in various implementations, sensing portion 367 and scale pattern 380 may be substantially planar (e.g., they may include or be formed on a substantially planar substrate), and sensing portion 367 may be configured to be mounted substantially parallel to periodic scale pattern 380 and with a nominal operating gap GapZ ​​between their conductors. For example, in various embodiments, nominal operating gap GapZ ​​may be at least 0.075*W1 to facilitate practical assembly and alignment tolerances. In some such embodiments, the nominal operating gap may be at least 0.15*W1. As shown in FIG. 4, the central magnetic flux CF is generally effectively coupled through the sensing element SEN14 over a practical range of the operating gap. However, due to the operating gap, at least a portion of the peripheral magnetic flux MF may not be effectively coupled through the sensing element SEN14. For example, as exaggerated in FIG. 4, at a relatively large dimension of the operating gap GapZ, none of the peripheral magnetic flux lines MFL1-MFL3 are coupled through the sensing element SEN14 and do not contribute to the current Isense. As a result, in the configuration qualitatively illustrated in FIG. 4, the effective width Weff (shown by the dashed bar in FIG. 4) of the signal modulation element SME sensed by the sensing element SEN14 corresponds only to the coupled central magnetic flux line CFL. As can be seen from FIG. 4, even if the operating gap GapZ ​​is reduced to, for example, couple the peripheral magnetic flux line MFL3 through the sensing element SEN14, the effective width Weff remains smaller than the average dimension DSME of the signal modulation element SME.

[0070] 2, it may be advantageous for a signal modulating element SME to have a mean dimension DSM that is greater than a desired effective width W to generate a desired maximum signal variation and / or a desired signal profile versus displacement as it passes through that sensing element S along the measurement axis. For example, in some embodiments, it may be desirable for the dimension W to be approximately 0.5*W, which, according to the foregoing discussion, means that when using an actual operating gap GapZ, it may be desirable for the mean dimension DSM of the signal modulating element SME to be at least 0.66*W, or 0.7*W, or more in some such embodiments.

[0071] It should be understood that if the signal modulating element SME is a conductive plate rather than a conductive loop as shown in FIG. 4, a distribution of “concentric” eddy currents may be generated in such a conductive plate in response to the generated changing magnetic field GMF. These eddy currents are operationally comparable to the induced currents Iind shown in FIG. 4. If a conductive plate has the same average dimension Dsme as the conductive loop SME shown in FIG. 4, the distributed “concentric” pattern of the eddy currents will result in their “equivalent current location” being somewhere inside the edge of the conductive plate, resulting in an even smaller effective width Weff than that associated with a similarly sized conductive loop. Consequently, in addition to providing a relatively large value for the average dimension Dsme when using a relatively large operating gap between the sensing portion 367 and the scale pattern 380, it may be particularly desirable for the conductive plate-type signal modulating element SME to have an average dimension Dsme toward the larger end of the desirable range outlined above. For example, the inventors have found that an average dimension Dsme between 0.7*W1 and 0.8*W1 is advantageous in some such embodiments.

[0072] As a further consideration, with respect to a desired signal profile versus displacement, it should be understood that undesired spatial harmonics present in the signal profile generally depend on the shape of the signal modulating element SME and its effective width Weff, as well as the shape and width of the sensing element SEN and the operating gap therebetween. For example, in the detector and scale configuration described above, even spatial harmonics are largely eliminated from the detected signal when the effective width Weff is approximately 0.5*W1. However, odd spatial harmonics, such as those corresponding to 0.33*W1, may remain. U.S. Patent Application Serial No. 16 / 021,528, published as US2020 / 0003581, suggests that configuring the signal modulating element SME to provide an effective width Weff of 0.66*W1 tends to suppress odd spatial harmonics corresponding to 0.33*W1. The inventor has also recently learned that the '708 patent suggests that configuring a signal-modulating element to have an effective width of 5 / 6*W1 (approximately 0.83*W1), regardless of whether or not it has a 1 / 6*W1 slot in its center, tends to suppress odd spatial harmonics corresponding to 0.33*W1. Note that this does not take into account the effective width Weff discussed above, and therefore may not operate as described in the '708 patent. In any event, these configurations did not actually achieve the expected or desired level of spatial filtering. Given the high accuracy already achieved by state-of-the-art electromagnetic inductive encoders known to date, these configurations did not provide the expected or predicted level of spatial filtering and did not provide a desirable improvement or advancement over the state of the art in this regard.

[0073] As disclosed herein, the inventors have discovered specific configurations of sensing elements SEN that can be used in combination with the configuration of the signal modulating elements SME described above to ameliorate the spatial filtering drawbacks described above. Various desirable configurations of the shape of the sensing elements SEN are described in further detail below with reference to FIGS. 6, 7, and 8. Various desirable configurations according to predetermined relationships for the position and / or shape of the sensing elements SEN are also described in detail below with reference to FIGS. 9-13 and 14-17. However, prior to that, the definitions or interpretations of certain dimensions and terms used in the description will be clarified with reference to the examples shown in FIGS. 5A and 5B. FIGS. 5A and 5B are plan views schematically illustrating certain aspects of embodiments of signal modulating elements and sensing elements, respectively, similar to those shown in FIG. 3, including additional examples of certain exemplary dimensions that can characterize those features in accordance with the principles disclosed herein.

[0074] 5A and 5B are schematic plan views of respective electromagnetic inductive encoder embodiments showing further examples of the dimensions and terms DSENmax, DSENavg, DSME, EffRSME, EffASEN, and EffYSEN outlined above with reference to FIG. 3. Dimension YSEG is also introduced and explained. It will be understood that several numbered components 5XX in FIGS. 5A and 5B may correspond to and / or provide similar operations or functions as similarly numbered components 3XX in FIG. 3 and may be understood similarly unless otherwise indicated.

[0075] 5A and 5B illustrate the spatial wavelength W1 and the aforementioned dimensions and terminology as they apply to the non-linear boundary profiles of the signal modulating element SME of FIG. 5A and the sensing element of FIG. 5B. The effective area EffRSME of the previously illustrated signal modulating element SME lies within the dashed boundary of the region or area of ​​the signal modulating element SME and is aligned with or overlaps with the internal region INTA, indicated by the dotted fill. DSME is the average dimension of the "effective area" EffRSME of the signal modulating element SME along the measurement axis direction MA. In various embodiments, the average dimension DSME can be considered to be the area of ​​the effective area EffRSME of the signal modulating element SME divided by the y-axis dimension of that effective area EffRSME. For convenience and consistency of definition, for a conductive plate-type signal modulating element SME, the relevant dimension may correspond to the edge of the SME, and for a conductive loop-type signal modulating element SME, the relevant dimension may correspond to the centerline of the conductor. 5A and 5B, the internal region INTA of the magnetic field generating coil FGC has a dimension YSEP smaller than the negative y-axis dimension of the signal modulation element SME and is contained therein, so that the y-axis dimension of its effective region EffRSME is equal to the dimension YSEP. However, this need not be the case in all embodiments (e.g., as shown in FIG. 7), and the previous definition of the effective region EffRSME is more general, including cases where the y-axis dimension of the effective region EffRSME is smaller than the dimension YSEP.

[0076] The effective area EffASEN of the sensing element SEN, as outlined above, is within the solid boundary of the sensing element SEN and is aligned with or overlaps with the interior area INTA, as indicated by the hatched area. As outlined above, DSENmax is the maximum sensing element width dimension along the x-axis or measurement axis direction MA of the effective area EffASEN of the sensing element SEN. DSENavg is the average sensing element width dimension, defined as DSENavg = EffASEN / EffYSEN. As previously mentioned, EffYSEN is the dimension along the y-axis of the effective area EffASEN of the sensing element. In the specific embodiment shown in FIGS. 5A and 5B, the effective y-axis dimension EffYSEN is equal to YSEP. This is because each sensing element SEN has a maximum sensing element dimension along the y-axis that exceeds YSEP, and therefore its effective area EffASEN spans the entire dimension YSEP. In the particular embodiment shown in FIG. 5A, the effective area EffASEN has parallel sides perpendicular to the x-axis and a dimension YSEG that spans YSEP, so DSENavg is equal to DSENmax. YSEG is conveniently defined as the y-dimension of the conductor segments defining the sensing element SEN that are spaced apart by the largest dimension DSENmax and extend linearly along the y-axis. In the particular embodiment shown in FIG. 5B, the effective area EffASEN has a dimension DSENmax at its center along the y-axis, but its sides are tapered or curved toward the top and bottom of the effective area EffASEN. Therefore, as shown, DSENavg is somewhat less than DSENmax. For convenience and consistency of definition, when determining DSENavg=EffASEN / EffYSEN for the sensing element SEN, the relevant dimension may be taken to correspond to the centerline of the defining conductor. In the embodiment shown in FIGS. 5A and 5B, DSENmax is nominally 0.5*W1. However, this value is not limiting (for example, as shown in FIG. 8 below). The dimensions DSENavg of the sensing element SEN configuration shown in FIGS. 5A and 5B are not preferred according to the principles outlined below with reference to FIGS. 6, 7, and 8, and are presented only for clarity in defining or quantifying DSENavg.5B is the center-to-center spacing of the sensing elements SEN along the x-axis. In various embodiments, it may be advantageous for CCSEN to be 0.5*W1, regardless of the shape or dimension DSENavg of the sensing elements SEN.

[0077] 5A and 5B also show a dimension DSPC equal to W1 minus DSME. Describing the first method, the dimension DSPC can be described as corresponding to the "non-signal modulating space" between the first-type signal modulating elements SME. However, describing the second method more generally, which is applicable to various other embodiments of the periodic scale pattern, the dimension DSPC can be described as corresponding to the second-type signal modulating elements, which are disposed between the first-type signal modulating elements SME along the measurement axis. The second-type signal modulating elements are configured to be relatively less sensitive to magnetic flux changes than the first-type signal modulating elements SME. For example, in some embodiments, the second-type signal modulating elements include regions of non-conductive material. In some such embodiments, the second-type signal modulating elements include regions of a non-conductive scale substrate, and the first-type signal modulating elements SME include conductors fabricated and / or affixed to the non-conductive scale substrate. As another example, in some embodiments, the second type signal modulating element may include a "deeper recessed" area of ​​conductive material used to form the scale pattern, and the first type signal modulating element SME may include a "non-recessed" area of ​​conductive material.

[0078] Returning to the discussion of filtering the third-order spatial harmonic error component (with a period of 0.33*W1) from the detector element signal, as mentioned above, the inventors have discovered a specific configuration of detector elements SEN that can be used in combination with the signal modulation element SME configuration described above to overcome the drawbacks of spatial filtering. Various prior art techniques are known for filtering the third-order spatial harmonic error component from the detector element signal. One approach is to configure the detector element to have a sinusoidal waveform that theoretically contains only the fundamental spatial frequency corresponding to W1. However, due to various practical considerations, manufacturing limitations, and variations in assembly and gap, the third-order spatial harmonic error component cannot be completely suppressed. Another approach is to arrange a set of detector elements SETSEN at spatial phases separated by 0.33*W1 and process the resulting signal to remove the third-order spatial harmonic error component. While this method is relatively effective, in many applications, for practical reasons it is desirable to provide orthogonal signals (i.e., signals with spatial phases 0.25*W1 apart) from the set of sensing elements SETSEN, and therefore it may be difficult or impractical (e.g., due to layout constraints or interference) to arrange a set of sensing elements SETSEN with spatial phases 0.33*W1 apart.

[0079] To address the problems and deficiencies inherent in the approaches outlined above, the present inventors have discovered that configurations of sensing elements SEN that provide a particularly advantageous range of sensing element average dimensions DSENavg can be used in combination with the signal modulation element SME configurations outlined above to substantially filter and / or suppress third spatial harmonic error components. Surprisingly, for some encoder sensing portion and / or sensing element configurations, the particularly advantageous range does not include 0.33*W1, although this is clearly expected based on theoretical considerations. For example, as disclosed herein, sensing elements SEN configured to provide a sensing element average dimension DSENavg of at least 0.285*W1 and at most 0.315*W1 for a practical range of wavelengths W1 and operating gaps are particularly advantageous for some sensing portion and / or sensing element configurations when used in combination with signal modulation elements SMEs having average dimensions DSME of at least 0.55*W1 and at most 0.8*W1. Various desirable configurations of such sensing elements SEN are described in further detail below with reference to FIGS. 6, 7, and 8.

[0080] FIGS. 6, 7, and 8 are plan views illustrating various embodiments of a scale pattern 680 including a sensing element SEN and a signal modulating element SME. The disclosed embodiments are compatible with or can be used independently of the sensing element construction principles disclosed herein with reference to FIGS. 9-12. In any event, the disclosed embodiments are suitable for use with sensing portion 667 (and / or 767, or 867) and scale pattern 680 in an electromagnetic induction encoder such as that shown in FIG. 1. FIGS. 6, 7, and 8 also include examples of various dimensions that may characterize important features of a sensing element SEN. To facilitate understanding of the conductor layout of a sensing element SEN, the following figures indicate the polarity of the loop with arrows indicating current flow in the conductor segments and / or with "+" and / or "-" symbols inside the loops and / or with a (+) or (-) suffix on the label. It will be understood that some numbered and / or named components in Figures 6, 7, and 8 may correspond to and / or provide similar operation as similarly numbered or named components in Figures 5A and 5B and may be understood similarly unless otherwise indicated. Therefore, the following description will only highlight certain differences between the sensing element SEN and the signal modulating element SME.

[0081] The embodiment shown in Figure 6 includes a signal modulating element SME similar to that shown in Figures 5A and 5B, and has an effective area EffRSME with an average dimension DSME that is approximately 0.75*W1 (in this particular embodiment).

[0082] The sensing element SEN includes a conductor (shown as a solid line) on a first processing layer and a conductor (shown as a dashed line) on a second processing layer, which are connected via a feedthrough FT according to known methods (e.g., methods described in the cited documents). The field generating coil FGC is fabricated in this embodiment on a third processing layer to isolate it from the feedthrough FT. As shown in FIG. 6, the conductor of the sensing element SEN includes a y-axis segment having a short y-axis dimension YSEG, spaced apart along the x-axis by DSENmax=0.5*W1, and a segment tapering from the y-axis segment toward the feedthrough FT. The associated trapezoidal effective area EffASEN (shown as a solid hatched area in FIG. 6) has a y-axis dimension EffYSEN, which in this embodiment is equal to YSEP. In various embodiments using similar sensing element geometries and signal modulating elements SME, it has been surprisingly determined to be advantageous if the sensing elements SEN are configured such that DSENavg=EffASEN / EffYSEN is at least 0.285*W1 and at most 0.315*W1. In some embodiments, it may be particularly desirable for DSENavg to be at least 0.29*W1 and at most 0.31*W1. For a particular selection of DSENmax, various values ​​of DSENavg can be provided by appropriately dimensioning the YSEG and positioning the feedthroughs and adjacent conductors. In some such embodiments, the y-axis dimension YSEG should be at least 0.15*W1. In the particular embodiment shown, DSENmax is nominally 0.5*W1, but if desired, the conductors in the various layers can be configured to include overlapping x-axis segments between adjacent sensing elements SEN and the YSEG dimension so that DSENmax is less than 0.5*W1.

[0083] Figure 7 includes several numbered and / or named components that correspond to and / or may operate similarly to similarly numbered or named components in Figure 6 (and Figures 5A and 5B), and which may be understood similarly unless otherwise indicated. Therefore, the following description will highlight only certain differences between the sensing element SEN and the signal modulating element SME. The embodiment shown in Figure 7 includes a signal modulating element SME similar to that shown in Figure 6, and has an effective area EffRSME with an average dimension DSM E that is (in this particular embodiment) about 0.75*Wl.

[0084] The sensing element SEN is similar to that shown in FIG. 6 and includes a conductor on a first processing layer (shown by a solid line) and a conductor on a second processing layer (shown by a dashed line), which are connected via a feedthrough FT according to known methods (e.g., methods described in the cited documents). However, the feedthrough FT is located within the interior region INTA. This allows the field generating coil FGC to be fabricated on the first and / or third processing layers, which has the advantage of reducing the manufacturing cost of the sensing unit 767. The drawback is that the effective area EffASEN of the sensing element SEN is smaller than that of the embodiment shown in FIG. 6, potentially resulting in reduced signal strength. However, this may be a desirable trade-off depending on the application. The effective area EffASEN (shown by a hatched fill in FIG. 7) has a y-axis dimension EffYSEN, which is smaller than YSEP in this embodiment. In various embodiments using similar sensing element geometries and signal modulating elements SME, it has been surprisingly determined to be advantageous if the sensing elements SEN are configured such that DSENavg=EffASEN / EffYSEN is at least 0.285*W1 and at most 0.315*W1. In some embodiments, it may be particularly desirable for DSENavg to be at least 0.29*W1 and at most 0.31*W1. For a particular selection of DSENmax, various values ​​of DSENavg can be provided by appropriately dimensioning the YSEG and positioning the feedthroughs and adjacent conductors. In the particular embodiment shown, DSENmax is nominally 0.5*W1, but if desired, the conductors in the various layers can be configured to include overlapping x-axis segments between adjacent sensing elements SEN and those dimensioned YSEG such that DSENmax is less than 0.5*W1. In similarly shaped embodiments, if DSENmax is 0.5*W1 or less, then the YSEG dimension may need to be at least 0.14*EffYSEN or greater so that DSENavg is 0.285*W1 or greater.

[0085] Figure 8 includes several numbered and / or named components that correspond to and / or may operate similarly to similarly numbered or named components in Figure 6 (and Figures 5A and 5B), and which may be understood similarly unless otherwise indicated. Therefore, the following description will highlight only certain differences between the sensing element SEN and the signal modulating element SME. The embodiment shown in Figure 8 includes a signal modulating element SME similar to that shown in Figure 6, and has an effective area EffRSME with an average dimension DSM that is (in this particular embodiment) about 0.75*Wl.

[0086] The sensing element SEN is similar to that shown in FIG. 6 and includes conductors on a first processing layer (shown as solid lines) and a second processing layer (shown as dashed lines), which are connected via a feedthrough FT according to known methods (e.g., methods described in the cited documents). The field generating coil FGC is fabricated in this embodiment on a third processing layer to insulate it from the feedthrough FT. As shown in FIG. 8, the conductors of the sensing element SEN include y-axis segments having a long y-axis dimension YSEG (longer than and transverse to the dimension YSEP of the interior region INTA) and spaced apart along the x-axis by DSENmax, and a segment connecting these segments to the feedthrough FT. The associated rectangular effective area EffASEN (shown as a solid hatched area in FIG. 8) has a y-axis dimension EffYSEN, which in this embodiment is equal to YSEP. In this embodiment, DSENavg = DSENmax. In various embodiments using similar sensing element geometries and signal modulating elements SME, it has been surprisingly determined to be advantageous if the sensing elements SEN are configured such that DSENmax and DSENavg are at least 0.285*W1 and at most 0.315*W1. In some embodiments, it may be particularly desirable for DSENmax and DSENavg to be at least 0.29*W1 and at most 0.31*W1. The embodiment shown in FIG. 8 may be less sensitive to unwanted signal changes that may occur due to various misalignment errors.

[0087] With respect to the advantageous range of the dimension DSME of the signal modulating element SME described above, in many practical applications using the largest practical gap allowed by signal strength considerations, the most advantageous value of DSME may be at least 0.66*W1, or 0.7*W1, or even greater. For example, in various embodiments, a value of DSME of 0.75*W1 has been found to be particularly advantageous. However, as suggested in the preceding discussion, this may depend to some extent on the particular wavelength W1, the particular operating gap and operating frequency, and the particular shape and structure of the signal modulating element SME.

[0088] Regarding the advantageous range of the detector element SEN dimension DSENavg discussed above, for many practical applications using the largest practical gap allowed by signal strength considerations and the most advantageous value of DSME outlined above (e.g., DSME=0.75*W1), at least for embodiments using detector element geometries and signal-modulating elements SME similar to those outlined above with reference to FIGS. 6-9, the most advantageous combination of DSENavg values ​​may be in the range of 0.29*W1 to 0.31*W1. In such embodiments, DSENavg=0.30*W1 has been found to be particularly advantageous. However, as suggested by the preceding discussion, this will depend to some extent on the particular wavelength W1, the particular operating gap, the particular dimension DSME, and the particular shape and configuration of the signal-modulating element SME.

[0089] It should be appreciated that the third spatial harmonic error component in the signal from the signal modulating element set SETSEN is highly sensitive to the selection of dimensions within the ranges disclosed above. For example, the dimension DSENavg is desirably selected to reject the third spatial harmonic error component of the signal due to practical variations in fabricated dimensions and variations in the operating gap associated with the signal modulating element set SETSEN. Surprisingly, the inventors have discovered that, using a sensing element geometry and signal modulating element SME similar to those described above, in one embodiment configured to provide a value of 0.3*W1 for DSENavg, the error component associated with the third spatial harmonic error component is uniformly insensitive to variations in the dimension DSME of the signal modulating element SEN over the range DSME=0.72*W1 to DSME=0.79*W1. On the other hand, if DSENavg is changed by about 10% from this value (e.g., to 0.27*W1 or 0.33*W1), the error component of the third spatial harmonic increases by more than 10 times for a variation in detector element SEN in the range from DSME=0.72*W1 to DSME=0.79*W1, which is unacceptable.

[0090] One possible explanation for why the disclosed advantageous ranges for the dimension DSENavg differ significantly from the "naively" expected value of 0.33* is that DSENavg is influenced by error components due to variations in the detector impedance as a function of scale position. Such position-dependent impedance variations, which may be on the order of 1%, were not known or considered in the prior art. The advantageous ranges for DSENavg disclosed herein "adjust" or "tune" these impedance variations so that, when their signal component contributions are "aliased" and combined with other sources of third-order spatial harmonic error components, their combined effect cancels the third-order spatial harmonic error components. Such subtle effects and related design characteristics were not considered in the prior art. While particularly advantageous values ​​for DSENavg have been examined and identified above for detector and signal-modulating element embodiments similar to those outlined above with reference to Figures 6-8, it should be understood that such values ​​are illustrative and not limiting. For example, the advantageous range of DSENavg values ​​may be different for other detector and signal modulation element embodiments. This is likely due to the different error components resulting from the scale position-dependent impedance variations of the detector, as described above. Therefore, it should be understood that a particular detector configured according to the first or second type of predetermined relationship principle disclosed below with reference to FIGS. 9-17 may benefit from using a particular DSENavg value outside the range of 0.285*W1 to 0.315*W1. For example, a DSENavg value within a large range of 0.33*W1 ±15% may be useful for sufficiently reducing or suppressing unwanted third-order spatial harmonic detection signal components in various detectors configured according to the first or second type of predetermined relationship principle described below.In particular, when configured to sufficiently reduce or suppress unwanted third-order spatial harmonic detection signal components using a value of DSENavg within the range of 0.33*W1±15%, and further configured to reduce or suppress unwanted fifth-order (or seventh-order, or ninth-order) spatial harmonic detection signal components according to a first or second type of predetermined relationship principle set forth below, an unprecedented level of spatial filtering is provided for suppressing unwanted spatial harmonics. Furthermore, the unprecedented level of spatial filtering is achieved using a detector layout that is less complex, has higher performance, and is more economically manufacturable.

[0091] 9-13 are partially illustrative, partially schematic, plan views illustrating certain aspects of various exemplary configurations of sensing element sets SETSEN configured or arranged in accordance with a first type of predetermined relationship principle disclosed herein, in which the sensing elements SETSEN are arranged, together with compatible field generating coils FGC and scale patterns X80 (e.g., 980, 1380, etc.), to provide spatially filtered signals for use in detectors X67 (e.g., 967, 1367, etc.) of an electromagnetic induction encoder such as that shown in FIG. 1 , including various dimensions that can characterize the first type of predetermined relationship principle used to arrange those sensing elements SETSEN. By convention used herein, embodiments conforming to the first type of predetermined relationship principle (described in more detail below) may be referred to as first type embodiments for short.

[0092] The principles outlined below with reference to Figures 9-13 are advantageous for positioning sensing elements SEN to spatially filter potential fifth (or seventh, or ninth) harmonic components in a detected signal, and are particularly advantageous when used in combination with sensing elements SEN configured to spatially filter potential third harmonic components in a detected signal in accordance with the principles outlined above. However, it should be understood that the principles for positioning sensing elements SEN to spatially filter potential harmonic error components outlined below with reference to Figures 9-13 are not so limited. More generally, these principles can be used in combination with various other sensing elements SEN and signal modulating elements SME (e.g., known in the prior art) and still provide significant advantages.

[0093] Conventionally, the sensing elements SEN are periodically spaced along the measurement axis according to the wavelength W1, as described above. In particular, the positive polarity loops of the sensing elements SEN are typically uniformly spaced with a center-to-center spacing W1 or a multiple of W1, and the negative polarity loops of the sensing elements SEN are typically uniformly spaced with a center-to-center spacing W1 or a multiple of W1. Furthermore, the positions of the positive polarity loops and the negative polarity loops are typically uniformly offset from each other by (W1) / 2 along the measurement axis. Such positions and spacing are believed to be optimal for spatially filtering signal strength and potential spatial harmonics (second, fourth, etc.) contained in the detected signal. However, the inventors have found that, to obtain the highest accuracy in various applications, it may be desirable to use different positions and / or spacings of the sensing elements SEN, as described in more detail below, to provide spatial filtering to mitigate certain additional error components that may otherwise appear.

[0094] 9 is a plan view illustrating certain aspects of a first exemplary configuration of sensing element sets, SETSEN-Ph0 (also referred to simply as SETSEN), corresponding to a first spatial phase Ph0, configured according to a first type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector portion of an electromagnetic induction encoder such as that shown in FIG. 1 , along with a first compatible magnetic field generating coil FGC and a scale pattern 980, including various dimensions that characterize a sensing element configuration according to the principles disclosed herein. FIG. 9 includes several numbered and / or named components that correspond to and / or operate similarly to similarly numbered or named components in FIGS. 2, 3, and 8, and can be understood similarly unless otherwise indicated. Therefore, the following description will highlight only certain differences regarding the location of sensing elements SEN in detector portion 967.

[0095] Briefly, the sensing element SEN is similar to that shown in FIG. 8 in terms of its general shape, its effective area EffASEN, and its dimension DSENavg. In the particular embodiment shown in FIG. 9, DSENavg is approximately 0.3*W1, but as explained above, this is illustrative and not limiting in various embodiments of the first type. The sensing element SEN includes conductors on a first processing layer (shown as solid lines) and conductors on a second processing layer (shown as dashed lines), which are connected via feedthroughs FT (e.g., inner-layer feedthroughs insulated from the field-generating coil FGC) according to known methods (e.g., methods described in the cited documents). In some places in FIG. 9, the "non-looped" portions of the conductors on different layers are aligned with each other, and only a single conductor layer is shown. The presence of hidden "aligned" conductors would be inferred by one skilled in the art. The field-generating coil FGC is fabricated in this embodiment on a third processing layer to insulate it from the feedthroughs FT and the conductors connected to it. To facilitate understanding of the conductor layout of the sensing element SEN, in the following figures the polarity of the loop is indicated by arrows showing the current flow in the conductor segments and / or by "+" and / or "-" symbols inside the loop and / or by the suffix (+) or (-) on the label.

[0096] As implicitly shown in FIG. 9 , the scale extends along a measurement axis direction (MA) and includes a periodic scale pattern 980 with signal modulating elements SME and a spatial wavelength W1. The detector 967 is configured to be mounted proximate to the periodic scale pattern 980 for relative movement therebetween along the measurement axis direction MA. The detector 967 includes a magnetic field generating coil FGC and at least one respective set of detector elements SETSEN corresponding to a respective nominal spatial phase. In the particular embodiment shown in FIG. 9 , each set of detector elements SETSEN includes two subsets or portions SETSEN-Ph0sub1 and SETSEN-Ph0sub2, corresponding to a respective nominal spatial phase Ph0, as described in more detail below. The magnetic field generating coil surrounds an inner area INTA aligned with an effective area EffRSEN of the active signal modulating element SME. Each set of detector elements SETSEN is disposed along the measurement axis direction and fixed to a substrate. The members of a sensing element set are comprised of conductive loops or conductive loop portions that define a sensing element effective area EffASEN corresponding to the portion of the sensing element that is aligned with or overlaps the inner region INTA. The sensing element set SETSEN is configured to provide a detection signal responsive to its local contribution to the magnetic flux change provided by adjacent signal modulation elements SME of the scale pattern 980, corresponding to its nominal spatial phase Ph0. The signal processing unit may be operatively connected to the sensing unit to provide a coil drive signal as outlined earlier in this specification, and determines the relative position of the sensing unit and the scale pattern based on the detection signal input from the sensing unit.

[0097] As disclosed below with reference to FIGS. 9-13, in various embodiments of a first type configured to provide a spatially filtered detection signal, at least a first respective set of sensing elements SETSEN corresponding to a respective nominal spatial phase comprises combined features A1, B1 and C1, and further combines at least one of features D1 or E1 defined as follows:

[0098] A1) It has a plurality of positive polarity loops corresponding to a first winding direction or polarity and an equal number of negative polarity loops corresponding to a second winding direction or polarity opposite to the first winding.

[0099] B1) Each of the positive and negative polarity loops is defined as having a total sensing element effective area EffASEN that is aligned with or overlaps one or more of the internal regions, and an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more internal regions perpendicular to the measurement axis direction, and at least half of the positive and negative polarity loops are configured so that the sensing element average dimension DSENavg=(EffASEN / EffYSEN) along the measurement axis direction is within the range of 0.33*W1±15%.

[0100] C1) The positive polarity loops are configured such that the detector element active areas are disposed in a positive polarity loop defining relationship (positive loop defining relationship for short) with respect to the respective nominal spatial phases of the respective detector element sets, and the negative polarity loops are configured such that the detector element active areas are disposed in a negative polarity loop defining relationship (negative loop defining relationship for short) with respect to the respective nominal spatial phases of the respective detector element sets, wherein the positive loop defining relationship is configured such that up to half of the total detector element active areas of the plurality of positive polarity loops are shifted along the measurement axis in the first direction by (W1) / 4K relative to the respective nominal spatial phases, a nominally identical shift ratio of the total detector element active areas of the plurality of positive polarity loops is shifted along the measurement axis in the opposite direction from the first direction by (W1) / 4K relative to the respective nominal spatial phases, and the two shift ratios of the total detector element active areas of the positive polarity loop regions are shifted relative to each other by (W1) / 2K, where K is one of 3, 5, 7, and 9. The negative loop defining relationship comprises a configuration in which a shift ratio of up to half of the total detector element active area of ​​the plurality of negative polarity loops is shifted along the measurement axis in a first direction by (W1) / 4K relative to their respective nominal spatial phases, a nominally identical shift ratio of the total detector element active area of ​​the plurality of negative polarity loops is shifted along the measurement axis in a direction opposite the first direction by (W1) / 4K relative to their respective nominal spatial phases, and the two shift ratios of the total detector element active area of ​​the negative polarity loop regions are shifted relative to each other by (W1) / 2K.

[0101] D1) Each of the positive and negative loops is made up of a sensing element effective area EffASEN whose maximum dimension DSENmax in the measurement axis direction is at most 0.45*W1.

[0102] E1) Each detector element set corresponding to each nominal spatial phase (SETSENPh0) is configured in two parts: a first separation section consisting of the same number of positive and negative polarity loops; and a second separation section nominally aligned with the first separation section along the measurement axis direction and having the same number of positive and negative polarity loops as the first separation section, the first separation section and the second separation section being separated by a gap located along the measurement axis direction between the first separation section and the second separation section, the gap being at least as wide as one of the positive or negative polarity loops along the measurement axis direction, and the effective area of ​​the positive or negative polarity loops of each detector element set is not located within the gap.

[0103] As a result of implementing the combination of features A1, B1, and C1 above, and at least one of features D1 and E1, the set of detector elements SETSEN corresponding to each nominal spatial phase is practically configured to provide a spatially filtered detector signal or signals that can be used to reduce or suppress both potential unwanted third and Kth spatial harmonic detected signal components that may cause errors in the determined relative position between the detector and the scale pattern. In some embodiments of the first type, it may be particularly advantageous when K=5, as described in more detail below with respect to the various figures. In particular embodiments of the first type, it may be advantageous for at least half of the positive and negative polarity loops SEN to be configured to provide an average detector element dimension DSENavg that is at least 0.29*W1 and at most 0.31*W1, although this range is illustrative only and not limiting for particular embodiments.

[0104] 9-13 (and further below in Figures 14-17) each include a "reference grid" showing the location of several instances of each spatial phase Ph0 (also called and / or designated as the nominal spatial phase Ph0nom) separated by a wavelength W1, to more clearly show how each sensing element set SETSEN is constructed according to the principles described above. Also, for the same purpose, the central location of the effective area EffASEN of each sensing element SEN is indicated by the location of the dashed center line CLSEN.

[0105] Returning to further discussion of the embodiment shown in Figure 9, it will be appreciated by inspection of Figure 9 that, based on the reference grid and centerline indicators shown in Figure 9, the sensing element set SETSEN shown in Figure 9 implements the features A1, B1, C1 and D1 outlined above. A brief explanation follows.

[0106] 9, each sensing element set SETSEN comprises two similar subsets or portions SETSEN-Ph0sub1 and SETSEN-Ph0sub2 corresponding to respective nominal spatial phases Ph0. Each sensing element set SETSEN includes a number of positive polarity loops (indicated by a "+" inside the loop) corresponding to a first winding direction or polarity, and an equal number of negative polarity loops (indicated by a "-" inside the loop) corresponding to a second winding direction or polarity opposite to the first winding. In the particular embodiment shown in FIG. 9, the two subsets or portions SETSEN-Ph0sub1 and SETSEN-Ph0sub2 individually include an equal number of positive and negative polarity loops.

[0107] Of the total sensing element active areas of the positive polarity loops of sensing element SETSEN, a first half located in positive polarity loops SEN2 and SEN4 (i.e., a first half of the sum of their sensing element active areas EffASEN) is shifted in a first direction along the measurement axis direction MA by (W1) / 4K relative to the nominal spatial phase Ph0, and a second half of the total sensing element active areas EffASEN of the positive polarity loops located in positive polarity loops SEN5 and SEN7 is shifted in the opposite direction to the first direction along the measurement axis direction MA by (W1) / 4K relative to the nominal spatial phase Ph0nom. As a result, the first and second halves of the total sensing element active areas of the positive polarity loop regions are shifted relative to each other by (W1) / 2K along the measurement axis direction.

[0108] A first half of the total sensing element active areas EffASEN of the negative polarity loops of sensing element SETSEN, located in negative polarity loops SEN1 and SEN3, is shifted in a first direction along the measurement axis direction MA by (W1) / 4K relative to the (W1) / 2 offset from the nominal spatial phase Ph0nom, and a second half of the total sensing element active areas EffASEN of the negative polarity loops, located in negative polarity loops SEN6 and SEN8, is shifted in the opposite direction along the measurement axis direction MA by (W1) / 4K relative to the (W1) / 2 offset from the nominal spatial phase Ph0nom. As a result, the first and second halves of the total sensing element active areas of the negative polarity loop regions are shifted relative to each other along the measurement axis direction by (W1) / 2K. In the particular embodiment shown in FIG. 9 , the illustrated shift corresponds to K=5, which is illustrative and not limiting as already indicated in the description of feature C1.

[0109] In the particular embodiment shown in FIG. 9, the sensing element average dimension DSENavg (=EffASEN / EffYSEN) is illustrated to be within the range of 0.33*W1±15%, which is in accordance with the previous explanation of principle or feature B1.

[0110] As a result of implementing features A1, B1, and C1 as described above, each sensing element set SETSEN corresponding to each nominal spatial phase Ph0 shown in FIG. 9 is configured to provide a spatially filtered detection signal or signals that can be used to reduce or suppress (based on B1 above) potential unwanted third order spatial harmonic signal components that may contribute to errors in the determined relative position between the detector and the scale pattern, and to reduce or suppress (based on C1 above) potential unwanted Kth order spatial harmonic signal components.

[0111] With respect to the embodiment of feature D1, in the implementation shown in FIG. 9, the maximum sensing element dimension DSENmax is the same as the average sensing element dimension DSENavg, which is approximately 0.33*W1. This is less than the 0.45*W1 required by feature D1. One aspect of the utility of feature D1 in the embodiment shown in FIG. 9 is illustrated by the layout of sensing elements SEN4 and SEN5, which, in the illustrated embodiment, are shifted from one another by a total amount (W1 / 10). It will be appreciated that if the maximum dimension DSENmax of sensing elements SEN4 and SEN5 were wider, the layout of their conductors would overlap and / or interfere with each other, necessitating layout adjustments and / or sensing element irregularities or distortions (e.g., as depicted in the '130 patent) to facilitate feedthrough placement and / or provide isolation between the various conductors. The '130 patent is intended to provide an aligned center of gravity with the goal of eliminating errors due to misalignment of the "pitch" (rotation of the detector or scale about the Z axis). That solution implements its teachings using sensing elements with a nominal maximum dimension of W / 2, requiring numerous problematic layout adjustments and sensing area irregularities (e.g., as shown in FIG. 8 ). However, even with careful consideration, such layout and sensing area irregularities can adversely affect manufacturing cost, accuracy, sensitivity to misalignment, and the like. In contrast, by implementing feature D1 in the configuration shown in FIG. 9 , none of the sensing elements SEN of sensing element set SETSEN have sensing element effective areas EffASEN that overlap or interfere with the sensing element effective areas of other sensing elements SEN, avoiding layout irregularities, sensing element irregularities, and their associated deleterious effects despite shifting the sensing elements SEN in accordance with the principles disclosed herein.

[0112] In the particular embodiment shown in FIG. 9 , the sensing element set SETSEN is configured in a two-part configuration. The sensing element set SETSEN includes a first adjacent part SETSEN-Ph0sub1 having a plurality (two) of positive polarity loops (SEN1 and SEN3) and an equal number (two) of negative polarity loops (SEN2 and SEN4), and a second adjacent part SETSEN-Ph0sub2 having a plurality (two) of positive polarity loops (SEN5 and SEN7) and an equal number (two) of negative polarity loops (SEN6 and SEN8). The first and second adjacent parts are located closer to each other along the measurement axis direction than the width of one of the positive or negative polarity loops (hence, referred to herein as “adjacent” parts), and the loops of the first and second adjacent parts that are closest to each other (i.e., SEN4 and SEN5) have opposite loop polarities. However, this embodiment is illustrative and not limiting. Alternative examples of two-part configurations are described in more detail below. The area centroid CEN-SEETSEN-Ph0 of the sensing element set SETSEN will be described later with reference to FIGS.

[0113] Regarding signal processing for various two-part configurations, in various embodiments including a first and second part (e.g., two adjacent parts, or two separate parts, as further outlined), the electromagnetic inductive encoder may be configured according to either method M1 or M2 described below.

[0114] Method M1) The first part is configured to output a first detection signal (e.g., a voltage signal V0 between detection signal output connections SDS1 and SDS2), the second part is configured to output a second detection signal (e.g., a voltage signal V0' between detection signal output connections SDS1' and SDS2'), and the signal processing part is configured to determine a relative position between the detection part and the scale pattern based at least in part on a combination of the first and second signals.

[0115] Method M2) The first portion is connected in series with the second portion to form a composite signal, the series connection being configured such that the signal contributions of each of the first and second portions are added in the composite signal, and the signal processing unit is configured to determine a relative position between the detection unit and the scale pattern based at least in part on the composite signal.

[0116] One exemplary embodiment of a series connection by M2 can be described with reference to the alignment trace zone ATZ shown in FIG. 9. In particular, the feedthroughs shown in the alignment trace zone ATZ may be eliminated, and the "solid" traces of sensing elements SEN4 and SEN5 that contact the alignment trace zone ATZ may be connected by traces that cross the alignment trace zone ATZ on the metal layer on which they are both located. Similarly, the "dashed" traces of sensing elements SEN4 and SEN5 that contact the alignment trace zone ATZ may be connected by traces that cross the alignment trace zone ATZ on the metal layer on which they are both located. If the two connecting traces on the two layers are aligned with each other, no loop area will occur, causing significant signal disruption. When such a series connection is used, one of the pairs of sense signal output connections SDS1 and SDS2, or SDS1′ and SDS2′ (e.g., as shown in FIG. 9 and / or other figures herein) may be omitted, and the associated connection point on its associated sense element loop may be reconfigured for conductor conduction in a manner similar to other illustrated “connectionless” sense element loops. This type of series connection is illustrated in FIG. 16, which shows the series connection between its neighbors SETSEN-Ph90sub1 and SETSEN-Ph90sub2 (i.e., between respective sense elements SEN4 and SEN5). When neighbors are connected in series, in some embodiments, the resulting sense element set SETSEN may be visually represented as a continuous, uninterrupted sense element set (e.g., as shown in FIG. 16). In such cases, it should be understood that such a set of sensing elements SETSEN may, in some contexts, be interpreted as a single contiguous set, or alternatively, in some contexts as first and second adjacent portions connected to create the appearance of a continuous, uninterrupted set of sensing elements. In some embodiments, a series connection may be provided between an appropriate one of the detection signal output connections SDS1 or SDS2 and an appropriate one of the detection signal output connections SDS1' or SDS2'. Other alternative configurations of series connections will be apparent to those of ordinary skill in the art.It will be understood that the two-part signal processing and / or series connection options described above are generally applicable to any of the compatible two-part configurations shown in any of Figures 9-17. It will be understood that if a series connection were provided in the alignment trace zone ATZ between SEN4 and SEN5 in each of the sensing element sets shown in Figure 10, they could each be represented and / or considered as a visually continuous, uninterrupted sensing element set, as described above. In such a case, it will be understood that each sensing element set of Figure 10 would be considered to have features A1, B1, C1, and D1, but not feature E1.

[0117] FIG. 10 is a plan view showing one side of a second sensing element set SETSEN-Ph90 (abbreviated as SETSEN in some contexts below) corresponding to a second spatial phase Ph90 (denoted as Ph90nom in FIG. 10). This is configured similarly or identically to the first sensing element set SETSEN-Ph0 shown in FIG. 9 (except for its spatial phase), and therefore will not be described in detail here. The symbol for sensing element SEN shown in FIG. 10 is located at the center of the sensing element of the second sensing element set SETSEN-Ph90. This is shown superimposed on an unhighlighted representation of the first sensing element set corresponding to the first spatial phase Ph0 illustrated in FIG. 9, illustrating an operational quadrature configuration in which the spatial phases of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 differ by 90 degrees. Figure 10 includes several numbered and / or named components that may correspond to and / or operate similarly or identically to similarly numbered or named components in Figure 9, and which may be understood similarly unless otherwise indicated. Therefore, the following description will only highlight the specific relationship between the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90.

[0118] As shown in Figure 10, the second detector element set SETSEN-Ph90 has a corresponding spatial phase that is different by 90 degrees (i.e., shifted 90 degrees to the right) relative to the spatial phase of the first detector element set SETSEN-Ph0. It will be understood that the first detector element set SETSEN-Ph0 and the second detector element set SETSEN-Ph90 each include detector signal output connections SDS1 and SDS2, and SDS1' and SDS2' similar to those shown in Figure 9, although these connections are omitted from Figure 10 and other figures thereafter to avoid visual clutter. The first detector element set SETSEN-Ph0 and the second detector element set SETSEN-Ph90 operate together to output orthogonal signals that include advanced spatial filtering in accordance with the principles described above to provide very high accuracy position measurements. Both the first set of sensing elements SETSEN-Ph0 and the second set of sensing elements SETSEN-Ph90 incorporate features A1, B, C1, and D1, thereby providing the various advantages discussed above with reference to FIG. 9 . It will be appreciated from FIG. 10 that the layout and performance advantages associated with embodiments of these features also extend to the overlapping “quadrature layout” of the first set of sensing elements SETSEN-Ph0 and the second set of sensing elements SETSEN-Ph90. That is, it will be appreciated that the first set of sensing elements SETSEN-Ph0 and the second set of sensing elements SETSEN-Ph90 are easily laid out in a desired phase relationship without their conductors interfering with each other and without requiring irregularities or differences in the shapes of the sensing elements SETSEN. Thus, the layout and performance advantages outlined above are provided in a fully operational quadrature encoder layout as shown in FIG. 10 .

[0119] The embodiment shown in Figure 10 has aspects that are less than ideal for some applications. In particular, as shown in Figure 10, because the first set of sensing elements SETSEN-Ph0 and the second set of sensing elements SETSEN-Ph90 are substantially similar or identical and neither the first set of sensing elements SETSEN-Ph0 nor the second set of sensing elements SETSEN-Ph90 has feature E1, the area centroid CEN-SETSEN-Ph90 of the second set of sensing elements SETSEN-Ph90 is offset by a 90 degree spatial phase shift (i.e., W1 / 4) relative to the area centroid CEN-SETSEN-Ph0 of the first set of sensing elements SETSEN-Ph0. As taught in the '130 patent, when the area centroids of two different sets of sensing elements corresponding to two different spatial phases are offset, the pitch offset of their associated detectors (e.g., detector 967) or scales (e.g., scale pattern 980) results in differences in their respective operating gaps and signal strengths. In various applications, such pitch misalignment may be static or dynamic. In either case, static or dynamic differences in signal strength between two quadrature signals (or three three-phase signals) may require more complex signal processing (e.g., undesirably expensive and / or slow signal processing) or may cause undesirable measurement errors. The embodiment shown in FIG. 11A addresses these potential concerns.

[0120] FIG. 11A is a plan view showing a particular side of a second sensing element set SETSEN-Ph90 (abbreviated as SETSEN in some contexts below) corresponding to a second spatial phase Ph90 (denoted as Ph90nom in FIG. 11A ). It is a second exemplary configuration of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein. It is shown in FIG. 11A together with a first sensing element set SETSEN-Ph0 corresponding to the first spatial phase Ph0 illustrated in FIG. 9 . For illustrative purposes, the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 are offset from each other vertically in FIG. 11A to better illustrate their individual characteristics and relative alignment along the measurement axis direction. They are arranged in a quadrature configuration operable along the measurement axis direction, with the spatial phases of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 differing by 90 degrees. It will be appreciated that in an actual encoder, they are not offset from one another along the "y-axis" direction, but rather overlap one another, similar to the first and second sets of sensing elements shown in FIG.

[0121] Figure 11A includes several numbered and / or named components that may correspond to and / or operate similarly or identically to similarly numbered or named components in Figures 9 and / or 10, and which may be understood similarly unless otherwise indicated. Therefore, the following description of Figure 11A will highlight and describe only certain differences in the configuration of the second sensing element set SETSEN-Ph90.

[0122] The differences between the embodiment of the second sensing element set SETSEN-PH90 shown in FIG. 11A and the embodiment shown in FIG. 10 can be briefly explained as follows: The first sensing element set SETSEN-Ph0 can be considered unchanged from the description of FIGS. 9 and 10. The sensing elements SEN5-SEN8 of the second portion SETSEN-Ph90sub2 can be considered unchanged from the description of FIG. 10. The sensing elements SEN1-SEN4 of the first portion SETSEN-Ph90sub1 have been changed from the description of FIG. 10. In particular, relative to their positions in FIG. 10, in the embodiment shown in FIG. 11A, their layout has been shifted to the left by (W1) / 2, and the output signal connection is now provided to the rightmost sensing element SEN4, which remains associated with the trace of the positive polarity loop for conceptual continuity between FIG. 10 and FIG. 11. Based on the above explanation, there is no difference in the operation of the first portion SETSEN-Ph90sub1 as shown in FIG. 10 and FIG. 11 in terms of signal output and position. Also, the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 shown in FIG. 11A have features A1, B, C1 and D1, and therefore provide the various advantages described above with reference to FIG. 10.

[0123] Importantly, the embodiment shown in FIG. 11A is more ideal than the embodiment shown in FIG. 10 for applications that may involve pitch misalignment. In particular, because the first portion SETSEN-Ph90sub1 is shifted left by (W1) / 2 as shown in FIG. 11A relative to its position in FIG. 10, the overall area centroid CEN-SETSEN-Ph90 of the second sensing element set SETSEN-Ph90 is shifted left by (W1) / 4 so that it is aligned with the area centroid CEN-SETSEN-Ph0 of the first sensing element set SETSEN-Ph0. As taught in the '130 patent, when the area centroids of two different sensing element sets corresponding to two different spatial phases are aligned, their respective operating gaps and signal strengths are similarly affected by static or dynamic pitch misalignment, thereby eliminating most of the errors that may be introduced by pitch misalignment.

[0124] The embodiments of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 shown in FIG. 11A can be generally described as follows, without reference to FIG. 10. The first sensing element set SETSEN-Ph0 corresponds to the first spatial phase Ph0 and includes features A1, B1, C1, and D1 (but not feature E1). It is configured in a two-part configuration including a first neighboring portion SETSEN-Ph0sub1 having a plurality (two) of positive-polarity loops (SEN1 and SEN3) and an equal number (two) of negative-polarity loops (SEN2 and SEN4), and a second neighboring portion SETSEN-Ph0sub2 having a plurality (two) of positive-polarity loops (SEN5 and SEN7) and an equal number (two) of negative-polarity loops (SEN6 and SEN8). The first and second neighbors are located closer to each other along the measurement axis direction (hence, referred to herein as "neighbors") than the width of one of the positive or negative polarity loops, and the loops of the first and second neighbors closest to each other (i.e., SEN4 and SEN5) have opposite loop polarities. The second sensing element set SETSEN-Ph90 corresponds to the second nominal spatial phase Ph90 and has features A1, B1, C1, D1, and E1. It is configured to have feature E1 as follows: It is configured as a two-part structure including a first separator SETSEN-Ph90sub1 having an equal number (two) of positive polarity loops (SEN2, SEN4) and negative polarity loops (SEN1, SEN3), and a second separator SETSEN-Ph90sub2 nominally aligned with the first separator SETSEN-Ph90sub1 along the measurement axis direction and having the same number (two) of positive polarity loops (SEN5, SEN7) and negative polarity loops (SEN6, SEN8) as the first separator SETSEN-Ph90sub1. The first separator SETSEN-Ph90sub1 and the second separator SETSEN-Ph90sub2 are separated by a gap located along the measurement axis direction between the first separator and the second separator, the gap being at least as wide as one of the positive polarity loops or the negative polarity loops along the measurement axis direction.The positive polarity loop effective area EffASEN or the negative polarity loop effective area EffASEN of the second sensing element set SETSEN-Ph90 is not located within the gap.

[0125] The first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 can be further described as follows. The second sensing element set SETSEN-Ph90 corresponds to a nominal spatial phase Ph90 that differs by 90 degrees from the nominal spatial phase Ph0 of the first respective sensing element set SETSEN-Ph0. The second sensing element set SETSEN-Ph90 is configured such that the loops of its first and second isolation portions SETSEN-Ph90sub1 and SETSEN-Ph90sub2 that are closest to each other (e.g., SEN4 and SEN5) have the same loop polarity. The first sensing element set has a first area centroid of its total sensing element active area located along the measurement axis between its first and second adjacent portions. Each second sensing element set SETSEN-Ph90 has a second area centroid CEN-SETSEN-Ph90 of the total sensing element active area located along the measurement axis between the first isolation portion SETSEN-Ph90sub1 and the second isolation portion SETSEN-Ph90sub2. The first and second sensing element sets have their respective first area centroids CEN-SETSEN-Ph0 and second area centroids CEN-SETSEN-Ph90 arranged at the same position along the measurement axis direction.

[0126] As previously mentioned, when the area centroids of two different sensing element sets corresponding to two different spatial phases are aligned, their respective operating gaps and signal strengths are similarly affected by static or dynamic pitch misalignment, thereby eliminating most of the errors that may be introduced by pitch misalignment. According to one useful perspective, it should be understood that the second sensing element set SETSEN-Ph90 comprises feature E1 and therefore includes a gap (i.e., the gap shown between SEN4 and SEN5) that facilitates (or is a by-product of) rearranging and / or repositioning a particular loop or sensing element SEN to reposition the area centroid of the sensing element set SETSEN in a desired relationship relative to its nominal spatial phase so that the area centroids of the multiple sensing element sets SETSEN are aligned in a usable configuration.

[0127] 11A , it will be appreciated that, in contrast to the field centroid alignment technique disclosed in the '130 patent, the first set of sensing elements SETSEN-Ph0 and the second set of sensing elements SETSEN-Ph90 shown in FIG. 11A can be easily laid out with their field centroids aligned in a desired phase relationship without their conductors interfering with one another and without requiring irregularities or differences in the shapes of the sensing elements SEN. Thus, using the combination of features A1, B1, C1, D1, and E1 shown with reference to FIG. 11A provides the layout and performance advantages described with reference to FIGS. 9 and 10 in a fully operational quadrature encoder layout, while also providing the advantages associated with aligned field centroids.

[0128] 11A , it will be appreciated that each positive or negative polarity loop (e.g., each sensing element SEN) included in one of the first sensing element sets SETSEN-Ph0 or second sensing element sets SETSEN-Ph90 is configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective areas EffASEN of each other positive or negative polarity loop included in the same one of the first or second sensing element sets. It will be appreciated that the first type of embodiment outlined above with reference to FIGS. 9, 10, and 11A can provide unprecedented levels of spatial filtering that suppress multiple unwanted spatial harmonic signal components using a detector layout that is less complex, higher performance, and more economical to manufacture than prior art spatial filtering detectors (e.g., such as those disclosed in the '130 patent).

[0129] FIG. 11B is a plan view showing a particular side of a first sensing element set SETSEN-Ph0 (abbreviated as SETSEN in some contexts below) corresponding to a first spatial phase Ph0 (denoted as Ph0nom in FIG. 11B). It is a third exemplary configuration of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein. It is shown in FIG. 11B together with a second sensing element set SETSEN-Ph90 corresponding to the second spatial phase Ph90 illustrated in FIG. 11A. For illustrative purposes, the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 are offset from each other vertically in FIG. 11B to better illustrate their individual characteristics and relative alignment along the measurement axis direction. They are arranged in a quadrature configuration operable along the measurement axis direction, with the spatial phases of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 differing by 90 degrees. It will be appreciated that in an actual encoder, they are not offset from one another along the “y-axis.” Rather, they overlap one another, similar to the first and second sets of sensing elements shown in FIG. 10. FIG. 11B includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in FIG. 11A, and these may be understood similarly unless otherwise indicated. The second set of sensing elements SETSEN-Ph90 in FIG. 11B can be considered unchanged from the description of FIG. 11A. Therefore, the following description of FIG. 11B will highlight only certain differences in the configuration of the first set of sensing elements SETSEN-Ph0.

[0130] The difference between the embodiment of the first sensing element set SETSEN-Ph0 shown in FIG. 11B and the embodiment shown in FIG. 11B can be briefly explained as follows: Relative to the position in FIG. 11A, in the embodiment shown in FIG. 11B, the first portion SETSEN-Ph0sub1 has been moved to the left by (W1) / 2, and the second portion SETSEN-Ph0sub2 has been moved to the right by (W1) / 2. Output signal connections are now provided to the rightmost sensing elements SEN4 and SEN6, which remain associated with the traces of the positive polarity loop for conceptual continuity with FIG. 11A. Based on the above explanation, there is no difference in the operation of the first sensing element set SETSEN-Ph0 as shown in FIGS. 11B and 11A in terms of signal output and position.

[0131] The embodiments of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 shown in FIG. 11B can be comprehensively described as follows: The second sensing element set SETSEN-Ph90 corresponds to the second spatial phase and includes features A1, B1, C1, D1, and E1. The loops of the first isolation unit SETSEN-Ph90sub1 and the second isolation unit SETSEN-Ph90sub2 that are closest to each other (e.g., SEN4 and SEN5) are configured to have the same loop polarity. All of this is the same as described for FIG. 11A. In contrast, the first sensing element set SETSEN-Ph0 corresponding to the first nominal spatial phase Ph0 includes feature E1 in addition to features A1, B1, C1, and D1 included in FIG. 11A. Since the second sensing element set SETSEN-Ph90 has a first separation portion SETSEN-Ph90sub1 and a second separation portion SETSEN-Ph90sub2 separated by a gap equal to or greater than the width of one of the positive polarity loop SEN or the negative polarity loop SEN, it is clear that the second sensing element set SETSEN-Ph90 has feature E1. The positive polarity loop effective area EffASEN or the negative polarity loop effective area EffASEN of the second sensing element set SETSEN-Ph90 is not located within the gap.

[0132] The first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 can be further described as follows: The second sensing element set SETSEN-Ph90 corresponds to a nominal spatial phase Ph90 that differs by 90 degrees from the nominal spatial phase Ph0 of the first respective sensing element set SETSEN-Ph0. The first sensing element set SETSEN-Ph0 is configured such that the loops of its first and second isolation portions SETSEN-Ph0sub1 and SETSEN-Ph0sub2 that are closest to each other (e.g., SEN4 and SEN5) have opposite loop polarities. The first sensing element set has a first area centroid of its total sensing element active area located along the measurement axis between its first and second adjacent portions. Each second sensing element set SETSEN-Ph90 has a second area centroid CEN-SETSEN-Ph90 of the total sensing element active area located along the measurement axis between the first isolation portion SETSEN-Ph90sub1 and the second isolation portion SETSEN-Ph90sub2. The first and second sensing element sets have their respective first area centroids CEN-SETSEN-Ph0 and second area centroids CEN-SETSEN-Ph90 arranged at the same position along the measurement axis direction.

[0133] The foregoing discussion indicates that the inclusion of feature E1 in one (as in FIG. 11A) or both (as in FIG. 11B) of the two respective sets of sensing elements facilitates alignment of the area centroids of the two respective sets of sensing elements. Based on the foregoing discussion, it will be appreciated that the embodiment shown in FIG. 11B provides all of the various advantages outlined above with reference to FIG. 11A.

[0134] FIG. 12 is a plan view illustrating certain aspects of a first set of sensing elements SETSEN-Ph0 and a second set of sensing elements SETSEN-Ph90 corresponding to a first spatial phase Ph0 and a second spatial phase Ph90, which are fourth and fifth exemplary configurations of sensing element sets configured according to the first type of predetermined relationship principle disclosed herein. For illustrative purposes, the first set SETSEN-Ph0 and the second set SETSEN-Ph90 are offset from each other along the vertical direction in FIG. 12 to better illustrate their individual characteristics and their relative alignment along the measurement axis in an operating quadrature configuration in which the spatial phase Ph0 of the first sensing element set and the spatial phase Ph90 of the second sensing element set differ by 90 degrees. It will be understood that in an actual encoder, they would not be offset from each other along the “y-axis.” Rather, they would overlap each other, similar to the first and second sensing element sets illustrated in FIG. 10. Figure 12 includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in Figure 11A, and which may be understood similarly unless otherwise indicated. Therefore, the following description of Figure 12 will highlight and describe only certain differences in the configuration of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90.

[0135] The difference between the embodiment of the first detector element set SETSEN-Ph0 and the second detector element set SETSEN-Ph90 shown in FIG. 12 and the embodiment shown in FIG. 11A can be briefly explained as follows: In each detector element set shown in FIG. 12, the pair of detector elements SEN1 and SEN2 in their first portions SETSEN-Ph01 and SETSEN-Ph901 are shifted to the left by (W1) / 4K with respect to their nominal spatial phase, rather than to the right as in FIG. 11A. Conversely, in each detector element set shown in FIG. 12, the pair of detector elements SEN5 and SEN6 in their second portions SETSEN-Ph02 and SETSEN-Ph902 are shifted to the right by (W1) / 4K with respect to their nominal spatial phase, rather than to the left as in FIG. 11A.

[0136] 11B in either the first sensing element set SETSEN-Ph0 or the second sensing element set SETSEN-Ph90, can be comprehensively described as follows: According to a first aspect of the embodiment, at least the first (second) sensing element set SETSEN-Ph0 (SETSEN-Ph90) corresponding to each nominal spatial phase Ph0 (Ph90) comprises features A1, B1, C1, and D1, and is configured such that a plurality of pairs of sensing element active areas of adjacent positive and negative polarity loops are shifted by (W1) / 4K in a first direction along the measurement axis direction, and an equal number of pairs of sensing element active areas of adjacent positive and negative polarity loops are shifted by (W1) / 4K in a direction opposite to the first direction along the measurement axis direction, in accordance with feature C1.

[0137] Either the first sensing element set SETSEN-Ph0 or the second sensing element set SETSEN-Ph90 can be further described as follows: According to a second aspect of the embodiment, two respective pairs of adjacent loops at opposite ends of the first respective sensing element set (e.g., pair SEN1 and SEN2, and pair SEN7 and SEN8) have sensing element active areas of the positive polarity loop and negative polarity loop shifted in the same direction along the measurement axis in those two respective pairs.

[0138] Furthermore, the second sensing element set SETSEN-Ph90 shown in FIG. 12 has a feature E1 in addition to the features A1, B, C1, and D1, and the region centroid CEN-SETSEN-Ph0 and CEN-SETSEN-Ph90 are aligned.

[0139] Based on the foregoing, it will be appreciated that the embodiment shown in FIG. 12 provides all of the various advantages outlined above with reference to FIG. 11A . It may also provide additional advantages, such as the following: As previously mentioned, the aligned area centroids of the embodiment shown in FIG. 11A provide the advantage that the operating gaps and signal strengths of the first and second sets of sensing elements are similarly affected by static or dynamic pitch misalignment, thereby eliminating most of the errors that may be introduced by pitch misalignment. However, it can be appreciated that all of the sensing elements SEN in the left half of the embodiment are shifted in their respective first directions by a spatial phase shift of (W1) / 4K, and all of the sensing elements SEn in the right half of the embodiment are shifted in their respective opposite directions by a spatial phase shift of (W1) / 4K. Static or dynamic pitch misalignment results in an imbalance in the signal contributions of the right and left halves. This results in a degree of imbalance in the signal contributions due to the opposite spatial phase shifts of the right and left halves, reducing the sensitivity of position errors to pitch misalignment. In contrast, in the embodiment shown in Figure 12, a pair of sensing elements SEN are shifted in both directions in both the right and left halves of the embodiment, such that spatial phase errors due to static or dynamic pitch misalignment are reduced or eliminated. As one example, it will be appreciated that in the embodiment shown in Figure 12, sensing elements SEN1 and SEN8 at opposite ends of the right and left halves are shifted in the same direction by (W1) / 4K, such that both the amplitude and spatial phase of their total signal contribution are nominally unchanged by pitch misalignment.

[0140] It should be understood that the first aspect described above may provide some of the benefits described above in certain embodiments without the use of the second aspect, but in various embodiments it may be most advantageous to use the first and second aspects in combination, as shown in Figure 12.

[0141] FIG. 13 is a plan view illustrating certain aspects of a sixth exemplary configuration of sensing element sets, SETSEN-Ph90, corresponding to respective spatial phases Ph90, along with a second compatible magnetic field generating coil FGC and a scale pattern 1380, to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 . The sixth exemplary configuration of sensing element sets is configured according to a first type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 . The plan view illustrates various dimensions that characterize sensing element configurations according to the principles disclosed herein. FIG. 13 includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in FIGS. 9 and 12 , and these may be understood similarly unless otherwise indicated. In particular, the configurations of the sensing element sets SETSEN-Ph90 shown in FIGS. 13 and 12 are similar in that both implement features A1, B1, C1, D1, and E1 in a similar manner, and both implement the first and second aspects of the “shifted pair” configuration described above with reference to FIG. 12 in a similar manner. Therefore, the following description will only highlight certain differences of the sensing element set SETSEN-Ph90 related to the "two-track" magnetic field generating coil FGC and its adaptation to operate in conjunction with the scale pattern 1380 in the detection portion 1367.

[0142] The detection portion 1367 is arranged in a "two-track" configuration, which can be understood based on the following brief description and similar embodiments disclosed in U.S. Pat. No. 10,775,199 (the '199 patent), the entirety of which is incorporated herein by reference. Briefly, the scale pattern 1380 includes signal modulating elements SME disposed in a first track FPT and a second track SPT extending along the measurement axis direction MA, as shown. The field generating coil FGC is configured to have a first portion surrounding a first internal area portion FINTA aligned with the first track FPT, and a second portion surrounding a second internal area portion SINTA aligned with the second track SPT. The connections and current flow between the portions of the field generating coil FGC can be understood based on the example current flow arrows shown in FIG. 13 .

[0143] In this embodiment, in accordance with previously disclosed principles, the first sensing element set SETSEN-Ph0 includes two separate sections SETSEN-Ph90sub1 and SETSEN-Ph90sub2, the layout of which includes minor modifications to enhance compatibility with two-track embodiments, as will be appreciated by those skilled in the art. The first sensing element set SETSEN-Ph0 corresponding to the nominal spatial phase Ph0nom may include conductive loops that extend transversely in the measurement axis direction MA across the first and second inner area portions FINTA and SINTA and define first and second sensing element active area portions FEffASEN and SEffASEN, respectively, corresponding to portions of the sensing element SEN that are aligned with or overlap the first and second inner area portions FINTA and SINTA, respectively. Thus, the sensed signal contribution at each conductive loop is the combined sensed signal contribution from its respective first and second sensing element active area portions FEffASEN and SEffASEN. Compared with the previous description of FIG. 9, the sum of the first sensing element effective area portion FEffASEN and the second sensing element effective area portion SEffASEN of the sensing element SEN can be interpreted as the sensing element effective area EffASEN.

[0144] 13, the scale pattern 1380 is composed of signal modulation elements SME (or signal modulation element portions SME) periodically arranged in the first track FPT according to a wavelength W1 and signal modulation elements SME (or signal modulation element portions SME) periodically arranged in the second track SPT according to a wavelength W1, and the periodic arrangement of the first track FPT and the second track SPT is relatively offset by (W1) / 2. Further, the magnetic field generating coil FGC is configured to generate magnetic flux changes of a first polarity in the first internal area portion FINTA and generate magnetic flux changes of an opposite second polarity in the second internal area portion SINTA.

[0145] The nature of the combined detection signal contribution, in combination with the overlapping signal modulating element SME, is made clear by the paired symbols “+,+” or “+,-” or “-,-” or “-,+” within each sensing element SEN in FIG. 13 . The first symbol in the pair indicates the sensing element loop polarity, and the second symbol indicates the polarity of the magnetic flux generated in the corresponding interior area portion. As an example, for sensing element SEN2, the signal contribution from the first sensing element active area portion F EffASEN is a nominally positive contribution that is not reduced by the overlapping signal modulating element SME. The signal contribution from the second sensing element active area F EffASEN is a nominally negative contribution (due to negative magnetic flux), but this contribution is reduced or substantially eliminated by the overlapping signal modulating element SME. As a result, the net signal contribution of sensing element SEN2 for the illustrated scale position is a net positive signal contribution. The signal contributions of other sensing elements SEN and / or for other scale positions can be understood by analogy with the above discussion and / or as detailed in the '199 patent.

[0146] As indicated above, the sum of the first and second detector element effective area portions F EffASEN and S EffASEN of a detector element S E can be interpreted as the detector element effective area EffASEN for two-track embodiments, and this interpretation is applied appropriately in determining the average detector element dimension D SENavg as outlined in Principle or Feature B1 of the two-track configuration.

[0147] Regarding an additional aspect of the interpretation of the sensing element average dimension DSENavg outlined in Principle or Feature B1, in the case of a two-track configuration, the sensing element effective area EffASEN of each sensing element that is aligned with or overlaps two internal regions (e.g., FINTA and SINTA) may be defined as having an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more internal regions (e.g., FINTA and SINTA) perpendicular to the measurement axis direction MA. In the particular embodiment shown in FIG. 13, the sensing element average dimension DSENavg (=EffASEN / EffYSEN) according to the above interpretation is illustrated to fall within the range of 0.33*W1±15%, which is in accordance with the previous discussion of Principle or Feature B1.

[0148] It will be understood that the first or second type embodiments disclosed herein with reference to the two-track configuration shown in Figure 13 and further shown below in Figure 17 are exemplary only and not limiting. More generally, one of ordinary skill in the art, having the benefit of this disclosure and the teachings herein, will be able to adapt various spatial filtering configurations according to certain relationship principles or features of the first or second types disclosed and claimed herein for use with various other two-track embodiments, such as those disclosed in the '199 patent.

[0149] It will be understood that the sensing element sets SETSEN disclosed in the various embodiments of the first type described above with reference to Figures 9 through 13 are exemplary only and not limiting. For example, any of the sensing element sets SETSEN may be modified to include additional sensing elements SEN (or, in certain disclosed embodiments, a fewer number of sensing elements), provided that they are shaped and positioned such that the resulting sensing element set SETSEN has at least one of the features A1, B1, and C1, and the features D1 and E1, in the predetermined relationship as described above.

[0150] 9-13, but is not required in all embodiments, provided that feature E1 is included in at least one respective set of sensing elements. As one specific example with reference to FIG. 11A, if the shift direction of all sensing elements SEN in sensing element set SETSEN-Ph0 is reversed and all of the sensing elements SEN shown in FIG. 11A are replaced with sensing elements SEN shown in FIG. 6 (having a maximum dimension DSEmax of approximately 0.5*W1), the resulting encoder can be described as follows: The encoder comprises a plurality of respective sensing element sets (e.g., SETSEN-Ph0 and SETSEN-Ph90) corresponding to a plurality of respective spatial phases (e.g., Ph0 and Ph90), each of the sensing element sets comprising features A1, B1, and C1 (e.g., SETSEN-Ph0 does not include features D1 or E1), and at least one of the plurality of respective sensing element sets further comprises at least feature E1 (e.g., SETSEN-Ph90). The electromagnetic induction encoder is then configured to provide a plurality of spatially filtered detector signals that can be used to reduce or suppress potential unwanted third-order spatial harmonic detector signal components and potential unwanted Kth (fifth)-order spatial harmonic detector signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. The resulting encoder can be further described as follows: Each of the plurality of respective detector element sets (e.g., SETSEN-Ph0 and SETSEN-Ph90) has an area centroid of its total detector element active area located within its range along the measurement axis, and the plurality of respective detector element sets are configured such that their respective area centroids are located at nominally the same location along the measurement axis direction. Furthermore, the resulting encoder may be configured such that each positive or negative polarity loop included in any one of the plurality of respective detector element sets provides a respective detector element active area EffASEN that does not overlap with the detector element active area EffASEN of another respective positive or negative polarity loop included in the same one of the plurality of respective detector element sets.

[0151] If desired, a similar three-phase encoder could also be constructed to include three sets of sensing elements having features A1, B1, and C1, with at least two of the sets having feature E1.

[0152] Thus, while preferred embodiments of a first type have been shown and described, numerous variations in the arrangement of features shown and described will be apparent to those skilled in the art based on this disclosure.

[0153] 14-17 are partially illustrative, partially schematic, plan views illustrating certain aspects of various exemplary configurations of sensing element sets SETSEN configured or arranged in accordance with a second type of predetermined relationship principle disclosed herein such that the sensing elements SEN are configured to provide spatially filtered signals for use in the detectors (e.g., 1467, 1567, 1767, etc.) of an electromagnetic induction encoder such as that shown in FIG. 1. Also depicted are compatible field-generating coils FGC and scale patterns (e.g., 980, 1380). By convention, embodiments conforming to the second type of predetermined relationship principle (described in more detail below) may be referred to as second type embodiments for brevity.

[0154] The principles outlined below with reference to Figures 9-13 are advantageous in various alternative embodiments for arranging sensing elements SEN to spatially filter potential third, fifth, seventh, or ninth spatial harmonic components in a detected signal, and are particularly advantageous for forming sensing elements SEN to spatially filter potential fifth spatial harmonic components when used in combination with sizing sensing elements SEN according to the principles outlined above such that the dimensions DSENavg of the sensing elements SEN are configured to spatially filter potential third harmonic components in a detected signal. However, their application is not limited to the examples disclosed below. More generally, these principles can be used in combination with various other sensing element set SEN configurations and signal modulation elements SME in addition to those disclosed herein (e.g., as known in the prior art) and still provide significant advantages.

[0155] FIG. 14 is a plan view illustrating certain aspects of a first sensing element set SETSEN-Ph90 (abbreviated as SETSEN in some contexts below) corresponding to a first spatial phase Ph90, which is a first exemplary configuration of sensing element sets configured according to a second type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , along with the first compatible field-generating coil FGC and scale pattern 980 shown in FIG. 9 , including various dimensions that characterize sensing element configurations according to principles disclosed herein. FIG. 14 includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in previous figures, particularly FIGS. 9 and / or 11A , which can be understood similarly unless otherwise indicated. Briefly, the overall operation of the embodiment shown in FIG. 13 and the various elements therein can be understood by analogy with the description of FIGS. 9 and 11A above (and others, as applicable). The most significant difference between the sensing element set SETSEN-Ph90 shown in FIG. 14 and FIG. 11A is that the geometry of each sensing element SEN shown in FIG. 14 includes two “intra-loop” shift ratios, shifted in opposite directions by a predetermined amount, for the purpose of providing the desired spatial filtering within each sensing element SEN. When this feature is implemented in the second type of embodiment, the desired spatial filtering is achieved without the need to implement the principle or function C1 required in the first type of implementation. Because the overall sensing operation of the sensing element set SETSEN-Ph90 shown in FIGS. 14 and 11A is otherwise similar, the following description will emphasize only certain aspects of the configuration of the sensing element set SETSEN-Ph90 shown in FIGS. 14 and 11A that relate to the geometry of the sensing elements SEN and the intra-loop shift ratios they contain.

[0156] As disclosed below with reference to FIGS. 14-17, in various embodiments of a second type configured to provide a spatially filtered detection signal, at least a first respective set of sensing elements corresponding to a respective nominal spatial phase comprises features A2 and B2 defined as follows:

[0157] A1) It has a plurality of positive polarity loops corresponding to a first winding direction or polarity and an equal number of negative polarity loops corresponding to a second winding direction or polarity opposite to the first winding direction or polarity.

[0158] B2) At least half of the positive polarity loops and at least half of the negative polarity loops are configured such that the sensing element active areas are arranged in a predetermined intra-loop shift relationship with respect to the respective nominal spatial phase of the respective sensing element set.

[0159] The intra-loop shift relationships are configured such that, within each such loop, intra-loop shift ratios of up to half of their detector element active areas are shifted along the measurement axis direction in the first direction by (W1) / 4K relative to their respective nominal spatial phases, and nominally the same intra-loop shift ratios of their detector element active areas are shifted along the measurement axis direction in the opposite direction to the first direction by (W1) / 4K relative to their respective nominal spatial phases, whereby the two intra-loop shift ratios are shifted relative to each other by (W1) / 2K, where K is one of 3, 5, 7, or 9.

[0160] This results in a practical configuration whereby the set of detector elements corresponding to each nominal spatial phase (SETSENPh0) provides a spatially filtered detector signal or signals that can be used to reduce or suppress potential unwanted Kth spatial harmonic detector signal components that may cause errors in the determined relative position between the detector and the scale pattern.

[0161] As a result of implementing features A2 and B2 above, the set of detector elements SETSEN corresponding to each nominal spatial phase is thereby practically configured to provide a spatially filtered detector signal or signals that can be used to reduce or suppress potential unwanted Kth spatial harmonic detector signal components that may cause errors in the determined relative position between the detector and the scale pattern.

[0162] Each of Figures 14 to 17 includes a "reference grid" as previously described herein, with the central locations of the first track effective area FEffASEN and second track effective area SEffASEN of each sensing element SEN indicated by the location of a dashed center line CLSEN to illustrate how each sensing element SEN is configured in accordance with feature B2, as described in more detail below.

[0163] Returning to further discussion of the embodiment shown in FIG. 14 , based on the reference grid and centerline indicators shown in FIG. 14 , it will be understood that the sensing element sets SETSEN shown in FIG. 14 satisfy the construction principles or features A2 and B2 outlined above, as follows: In the embodiment shown in FIG. 14 , each sensing element set SETSEN-Ph90 corresponding to a respective nominal spatial phase Ph90 includes a plurality of positive polarity loops (indicated by a “+” inside the loop) corresponding to a first winding direction or polarity, and an equal number of negative polarity loops (indicated by a “−” inside the loop) corresponding to a second winding direction or polarity opposite to the first winding. In the embodiment shown in FIG. 14 , all of the positive polarity loops and all of the negative polarity loops are configured such that the sensing element effective areas EffASEN are disposed at a predetermined intra-loop shift relationship with respect to the respective nominal spatial phase Ph90nom of each sensing element set SETSEN-Ph90. The intra-loop shift relationships are configured such that within each such loop SEN, the intra-loop shift ratios ILSP of up to half of their detector element active areas are shifted along the measurement axis direction MA by (W1) / 4K relative to their respective nominal spatial phases Ph90nom, and nominally the same intra-loop shift ratios ILSP of their detector element active areas are shifted along the measurement axis direction MA in the opposite direction to the first direction by (W1) / 4K relative to their respective nominal spatial phases Ph90nom, whereby two intra-loop shift ratios ILSP (e.g., F EffASEN and S EffASEN) are shifted by (W1) / 2K relative to each other, where K is one of 3, 5, 7, or 9. Each such sensing element SEN is configured to combine two spatially filtered detection signal components (e.g., resulting from two in-loop shift ratios ILSP (i.e., FEffASEN and SEffASEN)) for the Kth spatial harmonic that are 180 degrees out of phase with each other, and to nominally cancel or suppress such Kth spatial harmonic signal components in their combined signal contribution.

[0164] 14, the in-loop shift ratio ILSP (e.g., F EffASEN and / or S EffASEN) of a detector element S E is nominally half of its detector element effective area EffASEN, which can provide the best spatial filtering. However, as also implied in the definition of Feature B2, in some embodiments where the in-loop shift ratio ILSP is less than or equal to half of the detector element effective area EffASEN, the provided spatial filtering may be sufficient.

[0165] 14, all of the positive polarity loops SEN and all of the negative polarity loops SEN have their sensing element active areas (e.g., EffASEN=FEffASEN+SEffASEN) arranged in a predetermined intra-loop shift relationship, which can provide the best spatial filtering. However, as implied in the definition of Feature B2, in some embodiments where only a majority of the positive polarity loops and negative polarity loops are configured with their sensing element active areas arranged in a predetermined intra-loop shift relationship, the provided spatial filtering may be sufficient.

[0166] The total detector element effective area EffASEN of the detector element SEN shown in FIG. 14 is defined as outlined earlier in this specification. This refers to the area within the detector element SEN that is aligned with or overlaps one or more internal regions (e.g., INTA in FIG. 14 ) and may be defined to have an effective y-axis dimension EffYSEN along the y-axis direction that is the sum of the dimensions of the one or more internal regions (e.g., INTA in FIG. 14 ) perpendicular to the measurement axis direction MA. In a specific embodiment of the second type shown in FIG. 14 , K=5, and the detector elements SEN are configured such that the detector element average dimension DSENavg along the measurement axis direction is within the range of 0.33*W1±15%, such that each detector element set corresponding to a respective nominal spatial phase (SETSENPh0) is configured to provide a spatially filtered detection signal or signals that can be used to reduce potential unwanted third-order spatial harmonic detection signal components and potential unwanted fifth-order spatial harmonic detection signal components. However, as indicated earlier, this embodiment is illustrative and not limiting. In various other embodiments, K may be 5, 7, or 9. In such embodiments, each set of sensing elements configured with features A2 and B2 is configured to provide a spatially filtered detection signal or signals that can be used to reduce potential unwanted third order spatial harmonic detection signal components and potential unwanted Kth order spatial harmonic detection signal components that may contribute to errors in the determined relative position between the detector and the scale pattern.

[0167] In the particular embodiment shown in FIG. 14 , the detector element set SETSEN-Ph90 includes two similar subsets or portions SETSEN-Ph01 and SETSEN-Ph02 arranged in mirror image of one another. One advantage of this configuration is that it reduces or eliminates position error sensitivity to lateral offset deviations (i.e., deviations of the detector portion 1667 and / or the scale pattern 980 due to translation along the y-axis) compared to using one of the portions SETSEN-Ph01 and SETSEN-Ph02 alone. However, this two-portion configuration is illustrative and not limiting. For example, either portion SETSEN-Ph01 or SETSEN-Ph02, each including features A2 and B2, could be used alone (e.g., as is, or by replicating the pattern of those detector elements SEN to increase their length), and the spatial filtering benefits described above would still be obtained in various embodiments.

[0168] FIG. 15 is a plan view illustrating certain aspects of a first sensing element set SETSEN-Ph90 (abbreviated as SETSEN in some contexts below) corresponding to a first spatial phase Ph90, which is a second exemplary configuration of sensing element sets configured according to a second type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 , along with the first compatible field-generating coil FGC and scale pattern 980 shown in FIG. 14 . FIG. 15 includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in FIG. 14 , and which can be understood similarly unless otherwise indicated. Therefore, the following description will highlight only certain differences between the configurations shown in FIG. 15 and FIG. 14 .

[0169] Briefly, the overall operation of the embodiment shown in Figure 15 and the various elements therein can be understood by analogy with the description of Figure 14 above (and others, as applicable). The only significant difference between Figure 15 and the sensing element set SETSEN-Ph90 shown in Figure 14 is that the orientation of some of the sensing elements SEN shown in Figure 15 is inverted or "inside out" compared to their orientation as shown in Figure 14. In particular, the pair of sensing elements SEN1 and SEN2 and the pair of sensing elements SEN5 and SEN6 are inverted or inside out compared to their orientation as shown in Figure 14.

[0170] The embodiment of the sensing element set SETSEN-Ph90 shown in FIG. 15 can be generally described as follows without reference to FIG. A first respective sensing element set SETSEN-Ph90 is configured according to features A2 and B2 and includes at least a first pair of positive and negative polarity loops (e.g., pair SEN1-SEN2 or pair SEN7-SEN8) configured to have nominally congruent shapes relative to their sensing element active areas, and at least a second pair of positive and negative polarity loops (e.g., pair SEN3-SEN4 or pair SEN5-SEN6) configured to have nominally congruent shapes relative to their sensing element active areas, wherein the congruent shapes in the first and second pairs are nominally mirror images of each other, and the positive and negative polarity loops of the first and second pairs are positioned adjacent to each other (e.g., pair SEN1-SEN2 and pair SEN3-SEN4, or pair SEN5-SEN6 and pair SEN7-SEN8).

[0171] Such a "mirror pair" configuration may, in some embodiments, provide improved accuracy and / or robustness to certain misalignments, such as reduced position error detection for pitch misalignment combined with lateral offset, or pitch misalignment combined with yaw misalignment (i.e., rotation of the detector 1767 or scale pattern 980 about the Z axis).

[0172] The embodiment of the sensing element set SETSEN-Ph90 shown in FIG. 15 can be further described as follows. Each first respective sensing element set SETSEN-Ph90 includes at least a first end pair of positive and negative polarity loops (e.g., pair SEN1-SEN2) configured to have nominally congruent shapes about their sensing element effective areas EffASEN within the first end pair, and at least a second end pair of positive and negative polarity loops (e.g., pair SEN7-SEN8) configured to have nominally congruent shapes about their sensing element effective areas EffASEN within the second end pair, where the nominally congruent shapes between the first and second end pairs are also nominally congruent between the first and second end pairs. It will be understood that the first and second end pairs are located at the first and second ends of the first respective sensing element set SETSEN-Ph90.

[0173] The advantages of a configuration with "mirror image pairs" may be enhanced in some embodiments when further comprising congruent end pairs, as outlined above and shown in Figure 15. However, it should be understood that a configuration with "mirror image pairs" that does not include congruent end pairs (e.g., a configuration with additional sensing elements and more mirror image pairs than illustrated in Figure 15) can still provide significant advantages as described above.

[0174] FIG. 16 is a plan view showing a particular side of the second sensing element set SETSEN-Ph0 corresponding to the second spatial phase Ph0 (denoted as Ph0nom in FIG. 16). It is a third exemplary configuration of sensing element sets configured according to the second type of predetermined relationship principle disclosed herein. It is shown in FIG. 16 together with the first sensing element set SETSEN-Ph90 corresponding to the second spatial phase Ph90 illustrated in FIG. 15. For illustrative purposes, the first sensing element set SETSEN-Ph90 and the second sensing element set SETSEN-Ph0 are offset from each other in the vertical direction in FIG. 16. They are arranged in a quadrature relationship operable along the measurement axis direction, with the spatial phases of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 differing by 90 degrees. It will be understood that in an actual encoder, they are not offset from each other along the “y-axis” direction. Rather, they overlap one another, similar to the first and second sets of sensing elements shown in Figure 10. Figure 16 includes several numbered and / or named components that correspond to and / or may operate similarly or identically to similarly numbered or named components in Figure 15, and can be understood similarly unless otherwise indicated. The first set of sensing elements SETSEN-Ph90 in Figure 16 can be considered unchanged from the description of Figure 15. Therefore, the following description of Figure 16 will highlight only certain aspects of the configuration of the second set of sensing elements SETSEN-Ph0.

[0175] Briefly, the differences between the embodiments of the second sensing element set SETSEN-Ph0 and the first sensing element set SETSEN-Ph90 shown in FIG. 16 are that the first portion SETSEN-Ph01 is shifted to the right by (W1) / 4 relative to the first portion SETSEN-Ph901, and the second portion SETSEN-Ph02 is shifted to the left by (W1) / 4 relative to the first portion SETSEN-Ph901. As a result, the effective loop polarity of sensing element SEN is as shown in FIG. 16. An output signal connection is provided to sensing element SEN5, which remains associated with the trace of the positive polarity loop for conceptual continuity with FIG. 15. In the particular embodiment shown in FIG. 16, only one output signal connection location is required because the first portion SETSEN-Ph01 and the second portion SETSEN-Ph02 are connected by a series connection in the alignment trace zone ATZ in the manner already outlined with reference to FIG. 9.

[0176] 16 can be generally described as follows: The first detector element set SETSEN-Ph0 and the second detector element set SETSEN-Ph90 corresponding to the nominal spatial phase Ph90 are configured according to features A2 and B2 and have a two-part configuration including a first separator SETSEN-Ph90sub1 having the same number of positive and negative polarity loops, and a second separator SETSEN-Ph90sub2 that is nominally aligned with the first separator SETSEN-Ph90sub1 along the measurement axis direction and has the same number of positive and negative polarity loops as the first separator SETSEN-Ph90sub1. The first isolation portion SETSEN-Ph90sub1 and the second isolation portion SETSEN-Ph90sub2 are separated by a gap located therebetween along the measurement axis direction, the gap being at least as wide as one of the positive polarity loops or the negative polarity loops along the measurement axis direction MA, and the effective area EffASEN of the positive polarity loop or the effective area EffASEN of the negative polarity loop of each first sensing element set SETSEN-Ph90 is not located within the gap. Each first sensing element set SETSEN-Ph90 is configured such that the loops of its first and second isolation portions that are closest to each other (i.e., SEN4 and SEN5) have the same loop polarity.

[0177] 16 further includes a second set of sensing elements SETSEN-Ph0 corresponding to a nominal spatial phase Ph0 that differs by 90 degrees from the nominal spatial phase Ph90. The second set of sensing elements SETSEN-Ph0 is configured according to features A2 and B2 and is also configured in a two-part configuration. The two-part configuration includes a first neighboring portion SETSEN-Ph0sub1 having the same number of positive and negative polarity loops, and a second neighboring portion SETSEN-Ph0sub2 that is nominally aligned with the first neighboring portion SETSEN-Ph0sub1 along the measurement axis direction and has the same number of positive and negative polarity loops as the first neighboring portion SETSEN-Ph0sub1. The first neighboring portion SETSEN-Ph0sub1 and the second neighboring portion SETSEN-Ph0sub2 are positioned closer to each other along the measurement axis direction than the width of one of the positive or negative polarity loops. The loops of the first adjacent portion and the second adjacent portion that are closest to each other (ie, SEN4 and SEN5) have opposite loop polarities.

[0178] 16, the first sensing element set SETSEN-Ph90 has a first area centroid CEN-SETSEN-Ph90 of the total sensing element active area located between its first isolation portion SETSEN-Ph90sub1 and second isolation portion SETSEN-Ph90sub2 along the measurement axis MA, and the second sensing element set SETSEN-Ph0 has a second area centroid CEN-SETSEN-Ph0 of the total sensing element active area located between its first neighboring portion SETSEN-Ph0sub1 and second neighboring portion SETSEN-Ph0sub2 along the measurement axis MA. The first sensing element set SETSEN-Ph90 and the second sensing element set SETSEN-Ph0 have their respective first area centroids CEN-SETSEN-Ph90 and second area centroids CEN-SETSEN-Ph0 arranged at the same position along the measurement axis direction, as shown in FIG.

[0179] 16 is configured to provide a spatially filtered detection signal or signals that can be used to reduce potential unwanted third-order spatial harmonic detection signal components and potential unwanted K-th order spatial harmonic detection signal components that may contribute to errors in the determined relative position between the detector and the scale pattern. Additionally, other features are included that eliminate position measurement errors associated with aligned area centroids and various types of misalignment. Furthermore, each positive or negative polarity loop (e.g., each detection element SEN) included in one of the first detection element set SETSEN-Ph90 or the second detection element set SETSEN-Ph9 is configured to provide a respective detection element effective area EffASEN that does not overlap with the detection element effective areas EffASEN of other respective positive or negative polarity loops included in the same one of the first or second detection element sets.

[0180] Generally speaking, it will be appreciated that the second type of embodiment outlined above with reference to Figures 14, 15 and 16 can provide unprecedented levels of spatial filtering that suppress multiple unwanted spatial harmonic signal components using a detector layout that is less complex, more powerful and more economical to manufacture than prior art spatial filtering detectors.

[0181] FIG. 17 is a plan view illustrating certain aspects of a first sensing element set SETSEN-Ph90 corresponding to a respective spatial phase Ph90, along with a second compatible field generating coil FGC and scale pattern 1380 shown in FIG. 13 , which is a fourth exemplary configuration of sensing element sets configured according to the second type of predetermined relationship principle disclosed herein to provide a spatially filtered signal for use in a detector of an electromagnetic induction encoder such as that shown in FIG. 1 . FIG. 17 is a “two-track” configuration including several numbered and / or named components that correspond to and / or may operate similarly to similarly numbered or named components of the two-track configuration shown in FIG. 13 , which may be similarly understood unless otherwise indicated. The configuration of sensing element set SETSEN-Ph90 shown in FIG. 17 is similar to sensing element set SETSEN-Ph90 shown and described with reference to FIGS. 15 and 16 in that both implement features A2 and B2 and arrange sensing elements SETSEN in a similar manner. The conductor layout of the sensing element SEN in FIG. 17 is adapted for cooperation with a two-track field generating coil FGC and scale pattern 1380, as can be understood by analogy with the description of FIG. 13 above.

[0182] Based on the foregoing discussion of similarities with previous figures, the embodiment shown in Figure 17, and its various advantages, can be understood by analogy with the previous discussion of Figures 13, 14, 15, and 16, and therefore need not be described in further detail here.

[0183] It will be understood that the sensing element set SETSEN in the various embodiments of the second type described above with reference to Figures 13 through 17 is illustrative only and not limiting. For example, any of the sensing element sets SETSEN, subsets, or portions may be modified to include additional sensing elements SEN, provided that the resulting sensing element set SETSEN is formed and configured to meet the predetermined relationship characteristics A2 and B2 as outlined above.

[0184] Furthermore, while the various embodiments disclosed above are configured such that the sensing elements comprising the sensing element active areas do not overlap with other sensing element active areas of other conductive loops or conductive loop portions included in the respective sensing element sets, such embodiments are exemplary and not limiting. Generally speaking, features A2 and B2 can be implemented in any desired sensing element arrangement, including overlapping arrangements commonly used in the prior art. In such embodiments, sensing elements comprising features A2 and B2 may provide additional spatial filtering of the Kth spatial harmonic, as described above, to enhance such embodiments.

[0185] By way of example, the various embodiments described above correspond to K=5 and are configured with sensing elements having an average sensing element dimension DSENavg within the range of 0.33*W1±15%, but such combinations are illustrative and not limiting, as would be apparent to one skilled in the art.

[0186] As another example, the sensing element set SETSEN-PH0 shown in Figure 16 may have two "separate" sections with the gap between its sections modified in a manner similar to that described with reference to the sensing element set SETSEN-PH0 shown in Figure 16 to provide a quadrature encoder configuration. Thus, the general configuration of the first sensing element set SETSEN-Ph0 and the second sensing element set SETSEN-Ph90 shown in Figure 16 is illustrative and not limiting.

[0187] As another example, each of the sensing element sets of a three-phase encoder may be configured in a manner similar to any of the various embodiments of the second type described above. In such an embodiment, each of the plurality of respective sensing element sets corresponding to the plurality of respective spatial phases is configured to have features A2) and B2) to provide a spatially filtered detected signal that can be used to reduce or suppress potential unwanted Kth spatial harmonic detected signal components that may contribute to errors in the determined relative position between the detector and the scale pattern.

[0188] While preferred embodiments of the second type have been shown and described, numerous variations in the arrangement of features shown and described will be apparent to those skilled in the art based on this disclosure. A variety of alternatives can be used to implement features A2 and B2 of a given relationship as disclosed herein.

[0189] It will be appreciated that the principles disclosed and claimed herein can be readily and desirably combined with various features disclosed in the incorporated documents and in commonly assigned, co-pending U.S. patent application Ser. No. 16 / 826,842, entitled "TRANSMITTER AND RECEIVER CONFIGURATION FOR AN INDUCTIVE POSITION ENCODER," filed March 23, 2020, the disclosure of which is incorporated herein by reference in its entirety. The various embodiments described above can be combined to provide further embodiments. All U.S. patents and patent applications referred to herein are incorporated herein by reference in their entirety. Aspects of the embodiments can be modified, if necessary, to employ concepts from various patents and applications to provide still further embodiments. These and other changes can be made to the practice in light of the above detailed description. Generally, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but rather to include all possible embodiments, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. An electromagnetic induction encoder usable to measure the relative position between two elements along a measurement axis, comprising: a scale including a periodic scale pattern including at least a first type of signal modulating elements and having a spatial wavelength W1, the scale including an active area extending along a measurement axis and aligned with or overlapping an interior region of the magnetic field generating coil; a detector mounted proximate to the periodic scale pattern and configured to move along a measurement axis direction relative to the periodic scale pattern; a signal processing unit operatively connected to the detection unit to provide a coil drive signal, and configured to identify a relative position between the detection unit and the periodic scale pattern based on a detection signal input from the detection unit; the first type signal modulating element includes a plurality of conductive plates or a plurality of conductive loops arranged along the measurement axis direction in correspondence with a spatial wavelength W1; The detection unit a magnetic field generating coil fixed to a substrate, surrounding an interior region that is aligned in operation with an active area of ​​the periodic scale pattern of the signal modulating element, and configured to generate magnetic flux variations in the interior region in response to the coil drive signal; at least one respective set of sensing elements arranged along a measurement axis direction and fixed on the substrate, the respective sets of sensing elements corresponding to respective nominal spatial phases; a member of the set of sensing elements is comprised of a conductive loop or conductive loop portion that defines a sensing element effective area EffASEN corresponding to a portion of the sensing element that is aligned with or overlaps the interior region; the sets of sensing elements are configured to provide respective detection signals responsive to local contributions to magnetic flux variations provided by adjacent signal modulating elements of the periodic scale pattern, corresponding to respective nominal spatial phases; At least a first respective set of sensing elements corresponding to a respective nominal spatial phase comprises features A2 and B2 defined as follows: Feature A2 includes a plurality of positive polarity loops corresponding to a first winding direction or polarity and an equal number of negative polarity loops corresponding to a second winding direction or polarity opposite to the first winding direction or polarity; Feature B2 is configured such that at least half of the positive polarity loops and at least half of the negative polarity loops have sensing element active areas disposed in a predetermined intra-loop shift relationship with respect to the respective nominal spatial phases of the respective sensing element sets; the intra-loop shift relationships are configured such that, within each such loop, intra-loop shift ratios of up to half of the detector element active areas are shifted along the measurement axis by (W1) / 4K in the first direction relative to their respective nominal spatial phases, and the same intra-loop shift ratios of the detector element active areas are shifted along the measurement axis by (W1) / 4K in the opposite direction to the first direction relative to their respective nominal spatial phases, whereby the two intra-loop shift ratios are shifted relative to each other by (W1) / 2K, where K is one of 3, 5, 7, or 9; a set of sensing elements corresponding to each nominal spatial phase are arranged in a practical configuration to provide a spatially filtered sensed signal or signals that can be used to reduce or suppress potential unwanted Kth spatial harmonic sensed signal components that may cause errors in the determined relative position between a sensing portion and the periodic scale pattern.

2. In feature B2, in the positive polarity and negative polarity loops configured by arranging the sensing element effective areas in the predetermined intra-loop shift relationship, the intra-loop shift ratio is half of the sensing element effective areas of those loops.

3. Feature B2: The electromagnetic induction encoder according to claim 1, wherein all of the positive polarity loops and negative polarity loops are configured in a state in which the sensing element effective areas thereof are arranged in a predetermined intra-loop shift relationship.

4. 2. The electromagnetic induction encoder of claim 1, wherein at least the first respective set of sensing elements is configured in accordance with Features A2 and B2, and includes at least a first pair of positive and negative polarity loops configured to have congruent shapes relative to their sensing element active areas, and at least a second pair of positive and negative polarity loops configured to have congruent shapes relative to their sensing element active areas, the congruent shapes in the first and second pairs being mirror images of each other, and the positive and negative polarity loops of the first and second pairs being positioned adjacent to each other.

5. 5. The electromagnetic induction encoder of claim 4, wherein the first respective set of sensing elements comprises at least a first end pair of positive and negative polarity loops configured to have congruent shapes about the sensing element active areas thereof within a first end pair, and at least a second end pair of positive and negative polarity loops configured to have congruent shapes about the sensing element active areas thereof within a second end pair, further configured to have congruent shapes between the first end pair and the second end pair, the first and second end pairs being located at first and second ends of the first respective set of sensing elements.

6. 2. The electromagnetic induction encoder according to claim 1, wherein K=5.

7. 7. The electromagnetic induction encoder of claim 6, wherein each sensing element in each sensing element set configured to have features A2 and B2 has a total sensing element effective area EffASEN that is aligned with or overlaps one or more of the internal regions, and is defined as having an effective y-axis dimension EffYSEN along a y-axis direction that is a sum of dimensions of the one or more internal regions perpendicular to the measurement axis direction, and at least half of the sensing elements in each sensing element set are configured such that an average sensing element dimension DSENaVg=(EffASEN / EffYSEN) along the measurement axis direction is within a range of 0.33*W1±15%, and each sensing element set is configured to thereby provide a spatially filtered sensing signal or signals usable to reduce potential undesired third and fifth spatial harmonic detected signal components that may contribute to errors in a determined relative position between a sensing feature and the periodic scale pattern.

8. 8. The electromagnetic induction encoder of claim 7, wherein each of the positive polarity or negative polarity loops included in each of the sensing element sets configured to have features A2 and B2 is configured to provide the respective sensing element effective areas EffASEN that do not overlap with the sensing element effective areas EffASEN of other respective positive polarity or negative polarity loops included in the first respective sensing element set.

9. at least a first respective set of sensing elements corresponding to each nominal spatial phase is configured according to features A2 and B2 and is a two-part configuration; The two-part configuration includes a first separation section having an equal number of positive and negative polarity loops; a second separation portion aligned with the first separation portion along the measurement axis direction and including the same number of positive polarity loops and negative polarity loops as the first separation portion; 2. The electromagnetic induction encoder according to claim 1, wherein the first separation portion and the second separation portion are separated by a gap located along the measurement axis direction between the first separation portion and the second separation portion, the gap being at least as wide as one of the positive polarity loop or the negative polarity loop along the measurement axis direction, and an effective area of ​​the positive polarity loop or the negative polarity loop of each of the first sensing element sets is not located within the gap.

10. It comprises either M1 or M2 below: Feature M1 is further characterized in that the first isolation portion in the first respective set of sensing elements is configured to output a first detection signal, the second isolation portion in the first respective set of sensing elements is configured to output a second detection signal, and the signal processor is configured to determine a relative position between the detection portion and the periodic scale pattern based at least in part on a combination of the first and second signals; 10. The electromagnetic induction encoder of claim 9, wherein feature M2 is configured such that the first isolated portion in the first respective set of sensing elements is connected in series with the second isolated portion in the first respective set of sensing elements to form a composite signal, the series connection being configured such that signal contributions of each of the first and second isolated portions are summed in the composite signal, and the signal processing unit is configured to determine a relative position between the sensing portion and the periodic scale pattern based at least in part on the composite signal.

11. each of the first sets of sensing elements is configured such that the loops of the first and second separation portions that are closest to each other have the same loop polarity; the electromagnetic induction encoder further comprising at least a second respective set of sensing elements corresponding to a respective nominal spatial phase that differs by 90 degrees from a nominal spatial phase of the first respective set of sensing elements, the second respective set of sensing elements being configured to include features A2 and B2 and having a two-part configuration; The two-part configuration comprises: a first adjacent portion having an equal number of positive polarity loops and negative polarity loops; a second adjacent portion aligned with the first adjacent portion along the measurement axis direction and including the same number of positive polarity loops and negative polarity loops as the first adjacent portion; the first and second adjacent portions are located closer to each other along the measuring axis direction than the width of one of the positive and negative polarity loops, and the loops of the first and second adjacent portions closest to each other have opposite loop polarities; each of the first sensing element sets has a first area centroid of its total sensing element active area located along a measurement axis between its first and second separations; the second respective set of sensing elements has a second area centroid of its total sensing element active area located along the measurement axis between its first and second neighbors; 10. The electromagnetic induction encoder according to claim 9, wherein the first and second sets of sensing elements have their respective area centroids arranged at the same position along the measurement axis direction.

12. 12. The electromagnetic induction encoder of claim 11, wherein each positive or negative polarity loop included in one of the first or second respective sensing element sets is configured to provide a respective sensing element effective area EffASEN that does not overlap with the sensing element effective area EffASEN of another respective positive or negative polarity loop included in the same one of the first or second respective sensing element sets.

13. each of the first sensing element sets is configured such that the loops of the first and second separation portions that are closest to each other have the same loop polarity; the electromagnetic inductive encoder further comprising at least a second respective set of sensing elements corresponding to a respective nominal spatial phase that differs by 90 degrees from a nominal spatial phase of the first respective set of sensing elements, the second respective set of sensing elements being configured in accordance with features A2 and B2 and having a two-part configuration; The two-part configuration includes a first separation section having an equal number of positive and negative polarity loops; a second separation portion aligned with the first separation portion along the measurement axis direction and including the same number of positive polarity loops and negative polarity loops as the first separation portion; the first and second separation portions are positioned apart from each other along the measurement axis direction by a distance greater than the width of one of the positive and negative polarity loops, and the loops of the first and second adjacent portions closest to each other have opposite loop polarities; each of the first sensing element sets has a first area centroid of its total sensing element active area located along a measurement axis between its first and second separations; each second set of sensing elements has a second centroid of its total sensing element active area located along the measurement axis between its first and second separations; 10. The electromagnetic induction encoder according to claim 9, wherein the first and second sets of sensing elements are arranged such that the centers of gravity of the first and second regions are located at the same position along the measurement axis direction.

14. the periodic scale pattern includes signal modulating elements arranged in first and second tracks extending along a measurement axis direction, the magnetic field generating coil is configured to surround a first internal region portion aligned with the first track and a second internal region portion aligned with the second track; 2. The electromagnetic induction encoder of claim 1, wherein at least one respective set of sensing elements corresponding to a respective nominal spatial phase comprises the sensing elements having features A2 and B2, the sensing elements comprising conductive loops each extending in the measurement axis direction across the first and second interior area portions and defining first and second sensing element active area portions corresponding to portions of the sensing element aligned with or overlapping the first and second interior area portions, respectively, and wherein a sensed signal contribution arising in each conductive loop is a combination of respective sensed signal contributions from its first and second sensing element active area portions.

15. the periodic scale pattern is composed of signal modulation elements or signal modulation element portions periodically arranged on the first track according to a wavelength W1, and signal modulation elements or signal modulation element portions periodically arranged on the second track according to a wavelength W1, and the periodic arrangements of the first track and the second track are relatively offset by (W1) / 2; 15. The electromagnetic induction encoder of claim 14, wherein the magnetic field generating coil is configured to generate magnetic flux changes of a first polarity in the first internal region portion and to generate magnetic flux changes of a second, opposite polarity in the second internal region portion.

16. 2. The electromagnetic induction encoder of claim 1, wherein a plurality of respective sets of sensing elements corresponding to a plurality of respective spatial phases comprise features A2 and B2, respectively, and the electromagnetic induction encoder is configured to thereby provide a plurality of spatially filtered detection signals usable to reduce or suppress potential unwanted Kth spatial harmonic detection signal components that may contribute to errors in the determined relative position between the detector and the periodic scale pattern.

17. each of the plurality of respective sensing element sets has an area centroid of its total sensing element active area located within the range along the measurement axis; 17. The electromagnetic induction encoder according to claim 16, wherein each of the plurality of sensing element sets is configured so that the area centroids of each of the sensing element sets are located at the same location along the measurement axis direction.

18. 2. The electromagnetic induction encoder according to claim 1, wherein each of the positive polarity or negative polarity loops included in any one of the plurality of respective sensing element sets is configured to provide the respective sensing element effective area EffASEN that does not overlap with the sensing element effective area EffASEN of another respective positive polarity or negative polarity loop included in the same one of the plurality of respective sensing element sets.

19. 20. The electromagnetic induction encoder of claim 18, wherein each sensing element in each of the plurality of sensing element sets has a total sensing element effective area EffASEN that is aligned with or overlapping one or more of the internal regions, and is defined as having an effective y-axis dimension EffYSEN along a y-axis direction that is a sum of dimensions of the one or more internal regions perpendicular to the measurement axis direction, and at least half of the sensing elements in each of the plurality of sensing element sets are configured such that an average sensing element dimension DSENaVg=(EffASEN / EffYSEN) along the measurement axis direction is within a range of 0.33*W1±15%, whereby the electromagnetic induction encoder is configured to provide a plurality of spatially filtered detected signals that can be used to reduce or suppress potential undesired third order spatial harmonic detected signal components and potential undesired Kth order spatial harmonic detected signal components that may contribute to errors in the determined relative position between the detector and the periodic scale pattern.

Images