Inductive encoder with shield structures

Abstract

To provide an improved combination of consistency of measurements, high accuracy, high resolution, robustness to contamination, compact size, ease of use, low cost, and the like.SOLUTION: An inductive encoder system comprises a scale including a periodic scale pattern, and a detector portion configured to move along a measuring axis direction relative to the periodic scale pattern. The detector portion includes a magnetic field generating portion configured to generate a changing magnetic flux, one or more sets of sensing elements, and a sensing portion configured to provide detector signals that respond to a local effect on the changing magnetic flux provided by the periodic scale pattern. Each set of sensing elements is coupled to a set of sensor vias. The detector portion further includes a plurality of shield structures SST, each shield structure SST is located proximate to a set of sensor vias and includes a plurality of shield vias, and in each shield structure, one or more shield loops are formed by the plurality of shield vias, which are coupled together by conductor portions.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to metrology, and more particularly, to inductive encoders. [Background technology]

[0002] Various position encoder configurations may include various types of inductive, optical, capacitive, magnetic, displacement, and / or position transducers that use various geometric configurations (e.g., transmitters and receivers) in a detector portion (e.g., as included in a readhead) to measure displacement between the detector portion and a scale.

[0003] As some examples of inductive encoders, U.S. Patent Nos. 6,011,389 (the '389 patent) and 6,124,708 (the '708 patent) describe induced current position transducers that can be used in high precision applications, U.S. Patent Nos. 5,973,494 (the '494 patent) and 6,002,250 (the '250 patent) describe incremental position calipers and linear scales that include signal generation and processing circuitry, and U.S. Patent Nos. 5,886,519 (the '519 patent), 5,841,274 (the '274 patent), and 5,894,678 (the '678 patent) describe absolute position calipers and electronic tape measures that use induced current 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 that are useful for improving the accuracy, robustness, and ease of alignment of inductive encoders. All of the foregoing are incorporated herein by reference in their entireties.

[0004] As described in these patents, inductive encoders can be manufactured using printed circuit board (PCB) technology and are largely immune to contamination. However, such systems may be limited in their ability to provide a particular combination of features desired by a user, such as a combination of measurement consistency, high accuracy, high resolution, robustness to contamination, compact size, ease of use, low cost, etc. Inductive encoder configurations that provide an improved combination of such features are desirable. Summary of the Invention

[0005] This Summary is provided to introduce selected 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] According to one aspect, an inductive encoder system configured to measure a relative position between two elements along a measurement axis direction is provided. The system includes a scale extending along a measurement axis direction, the scale including a periodic scale pattern with signal modulating elements, and a detector portion disposed proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern. The detector portion includes a magnetic field generating portion PRTFGE configured to generate a varying magnetic flux in response to a drive signal, and a sensing portion PRTSEN comprising one or more sets of sensing elements disposed along the measurement axis direction. Each set of sensing elements is coupled to a set of sensor vias, and the sensing portion PRTSEN is configured to provide a detector signal responsive to a localized effect on the varying magnetic flux provided by adjacent signal modulating elements of the periodic scale pattern. The detector portion also includes a plurality of shield structures SST disposed proximate to the set of sensor vias. Each shield structure SST includes a plurality of shield vias, and in each shield structure SST, one or more shield loops are formed by the plurality of shield vias coupled to each other by a conductor portion.

[0007] In an exemplary implementation, the plurality of shielding structures SST are configured to at least partially shield the set of sensor vias from stray magnetic fields resulting from the operation of the magnetic field generating unit PRTFGE. According to such an exemplary implementation, shielding the set of sensor vias is technically advantageous for reducing offset signal portions in the detector signal that would otherwise result from stray magnetic fields coupling into parasitic loops that may be formed by at least some of the set of sensor vias.

[0008] According to a further aspect, a method is provided for operating an inductive encoder system configured to measure a relative position between two elements along a measurement axis direction. The method generally includes three steps. A first step includes providing a drive signal to a magnetic field generating unit PRTFGE to generate a varying magnetic flux, where operation of the magnetic field generating unit PRTFGE generates one or more stray magnetic fields. A second step includes receiving a detector signal from the sensing unit PRTSEN, where at least one set of sensor vias is at least partially shielded from the one or more stray magnetic fields by a plurality of shield structures. A third step includes determining a relative position between the detector unit and the scale based at least in part on the detector signal.

[0009] According to a further aspect, a detector section is provided for use in an inductive encoder configured to measure a relative position between two elements along a measurement axis direction. The encoder includes a scale extending along the measurement axis direction, the scale including a periodic scale pattern including signal modulating elements. The detector section is disposed proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern. The detector section includes a magnetic field generating section PRTFGE configured to generate a varying magnetic flux in response to a drive signal, and a sensing section PRTSEN comprising one or more sets of sensing elements disposed along the measurement axis direction. Each set of sensing elements is coupled to a plurality of sensor vias, and the sensing section PRTSEN is configured to provide a detector signal responsive to a localized effect on the varying magnetic flux provided by adjacent signal modulating elements of the periodic scale pattern. The detector section further includes a plurality of shielding structures SST, each shielding structure SST disposed proximate to a set of sensor vias. Each shielding structure SST includes a plurality of shielding vias, and in each shielding structure SST, one or more shielding loops are formed by a plurality of shielding vias coupled to each other by a conductor section. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a block diagram of an inductive encoder system. [Diagram 2] FIG. 2 is a diagram of an implementation of a transducer including a detector portion and a scale such as may be used in the inductive encoder system of FIG. 1. [Diagram 3] FIG. 13 illustrates connections from a set of sensing elements of the detector portion to a set of sensor vias and to a processing portion, the connections forming a parasitic sensor loop. [Figure 4] FIG. 7 shows a shielding structure SST placed adjacent to a set of sensor vias as shown in FIGS. 3 and 6. [Diagram 5] FIG. 5 is a top view of the configuration of FIG. 4, further illustrating the stray magnetic field generated by current passing through the magnetic field generating vias. [Figure 6] FIG. 6 is an isometric view of an implementation of a transducer including a detector portion and a scale as may be used in the inductive encoder system of FIG. 1, showing magnetic field generating vias along with a shielding structure SST positioned adjacent to a set of sensor vias in a configuration similar to that of FIGS. 4 and 5. [Figure 7] FIG. 1 illustrates a cross-sectional portion of a printed circuit board (PCB) of a detector portion including two shielded vias that extend through six layers of the PCB. [Figure 8] FIG. 7 illustrates an isometric top view of the sensor vias along with the shielding structure SST of FIG. 6, in which the shielding vias of the shielding structure SST are shown coupled to each other by conductor portions (e.g., upper conductor portions) as part of a ground layer (e.g., layer L3) of the PCB. [Figure 9] FIG. 9 shows an isometric bottom view of the configuration of FIG. 8 (e.g., a view from below of the same layer L3 of FIG. 8), in which the shielding vias of the shielding structure SST are also shown coupled to each other by a conductor portion (e.g., a lower conductor portion) in a layer of the PCB different from the ground layer L3 (e.g., layer L4, not shown), thus forming a shielding loop within the shielding structure SST. [Figure 10] FIG. 1 shows two shield structures SST, each including four shield vias in a linear arrangement, arranged adjacent to both sides of a set of sensor vias including four sensor vias in a linear arrangement. [Figure 11] FIG. 1 shows two shield structures SST, each including six shield vias in a linear arrangement, arranged adjacent to both sides of a set of sensor vias including six sensor vias in a linear arrangement. [Figure 12] FIG. 7 is a diagram showing a shielding structure SST in a two-box arrangement surrounding a set of sensor vias having a configuration similar to that of FIGS. 4 to 6. [Figure 13] FIG. 4 is a flow diagram illustrating an example of a routine for operating an inductive encoder system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] FIG. 1 is a block diagram of example components of an inductive encoder system 100, including an inductive encoder 101. In various implementations, the inductive encoder 101 includes a scale 170 and a detector portion 167, which together form a transducer TDR. The inductive encoder 101 includes suitable user interface features, such as a display 138 and / or user-operable control elements 136 (e.g., switches, buttons, etc.). In some implementations, the inductive encoder 101 may be used as part of a wireless-only device or other configuration (e.g., the encoder 101 does not include a display). For example, the system 100 may include a corresponding remote display, such as part of a phone or tablet, via Bluetooth or other connection. The encoder 101 may further include a power source 165. All of these elements of the encoder 101 are coupled to a processing portion 166 (e.g., including one or more signal processors and, in some implementations, memory), which in various implementations may be embodied as signal processing and display electronics in an integrated circuit (IC) chip.

[0012] The processing unit 166 receives detector signals from the detector unit 167 and processes the detector signals to determine a position (e.g., in some implementations, an absolute position) of the detector unit 167 along the scale 170. It will be appreciated that the processing unit 166 can include any combination of signal processing circuitry and physical circuitry. In various implementations, the processing unit 166 and the detector unit 167 may be included as part of the electronic assembly 160 (e.g., disposed on a board, etc.). In various implementations, the control element 136, the display 138, and / or the power supply 165 may be included in the encoder 101 (and / or may be partially or completely included in a separate device or system, such as a host system or other device that may be part of the overall encoder system 100).

[0013] It will be appreciated that such inductive encoders have evolved over the years to provide a relatively optimized combination of high resolution and precision measurement, ease of use, compact size, low power operation, low cost, robustness to contamination, etc. Even small improvements in any of these factors are highly desirable but difficult to achieve, especially given the design constraints imposed to achieve commercial success in various applications. The principles disclosed herein provide improvements in some of these factors for a variety of applications.

[0014] Those skilled in the art will appreciate that the processing unit 166 and / or detector unit 167 (and / or any other control system or control portion described herein) may generally be implemented using any suitable computing device and / or system, including distributed or networked computing environments, etc. Such computing devices or systems may include one or more general-purpose or special-purpose processors (e.g., non-custom or custom devices) that execute software to perform the functions described herein. The software may be stored in memory, such as random access memory (RAM), read only memory (ROM), flash memory, etc., or a combination of such components. The software may also be stored in one or more storage devices, such as optical-based disks, flash memory devices, or any other type of non-volatile storage medium for storing data. The software may include program instructions that implement one or more program modules, including processes, routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In a distributed computing environment, the functionality of the program modules may be combined or distributed across multiple computing devices or systems, in either wired or wireless configurations, and may be accessed via service calls.

[0015] FIG. 2 is a diagram of an implementation of a transducer TDR' including a detector section 167' and a scale 170' (which may be, for example, a particular implementation of the transducer TDR, detector section 167, and scale 170 as described above with respect to FIG. 1). The detector section 167' includes a magnetic field generating section PRTFGE and a sensing section PRTSEN. In the simplified example of FIG. 2, the detector section 167' includes at least two substantially coplanar paths of wire or winding (PRTFGE and PRTSEN). The magnetic field generating section PRTFGE includes a magnetic field generating winding (e.g., in some implementations, it may also be called a transmitter winding or transmitter coil) that forms a large planar loop. In an exemplary implementation, the magnetic field generating winding defines (or surrounds) an interior region aligned with the periodic scale pattern 180 of the signal modulating element SME to generate a varying magnetic flux in the interior region in response to a magnetic field generating drive signal. The sensing unit PRTSEN includes a set of sensing elements SETSEN including sensing elements SEN+ and SEN- formed by a sensing winding (e.g., in some implementations, which may also be referred to as a receiver winding or receiver coil) that is substantially in the same plane or in a very close parallel plane (e.g., on an adjacent or otherwise very close layer of a PCB) as the magnetic field generating winding of the magnetic field generating unit PRTFGE.

[0016] The sensing windings of the sensing unit PRTSEN are laid out in one direction as indicated by the arrows in a zigzag or sinusoidal pattern, and then laid out in the opposite direction as indicated by the arrows, with the windings crossing over themselves (e.g., with insulation at the crossing points to avoid short circuits and / or on different PCB layers) to form alternating loops designated as sandwiched sensing elements SEN+ and SEN- as shown. As a result, each of the alternating loops of the sensing elements SEN+ and SEN- of the set of sensing elements SETSEN has a different winding direction compared to its adjacent loops. By applying an alternating (changing) current to the magnetic field generating unit PRTFGE, the magnetic field generating windings generate a time-varying magnetic field (changing magnetic flux) that extends through the loops of the sensing elements SEN+ and SEN- of the set of sensing elements SETSEN of the sensing unit PRTSEN.

[0017] The scale 170' includes a periodic scale pattern 180 that includes signal modulating elements SME. In various implementations, the periodic scale pattern 180 includes a first type of signal modulating elements SME that includes similar conductive plates (indicated by diagonal hatching in FIG. 2 ) that have a spatial wavelength WSME and that are arranged along a measurement axis direction MA that corresponds to the spatial wavelength WSME.

[0018] As a principle of operation, when the scale 170' including the scale periodic pattern 180 with the signal modulation elements SME approaches (proximity) the detector section 167', the changing magnetic field generated by the magnetic field generating section PRTFGE induces eddy currents in the proximity signal modulation element SME, which sets up a magnetic field from the signal modulation element SME that counteracts the changing magnetic field (changing magnetic flux). As a result, the magnetic flux experienced by the sense winding of the sensing section PRTSEN is changed or disrupted, which causes the sense winding to output a non-zero electromagnetic field (EMF) signal (voltage) at the output terminals V+ and V- of the sense winding of the sensing section PRTSEN, which increases or decreases and changes polarity as the signal modulation element SME moves in alignment between the "+" and "-" loops of the sensing elements SEN+ and SEN-, as will be explained in more detail below.

[0019] The distance between the locations of two sensing elements of the same polarity (e.g., between the location of a sensing element SEN+ and the location of the next sensing element SEN+) is defined as the pitch or wavelength WSEN of the set of sensing elements SETSEN of the sensing portion PRTSEN, which in certain implementations may be equal to the pitch or wavelength WSME of the periodic scale pattern 180 of the scale 170'. It can be seen that each sensing element SEN+ and SEN- thus has a length or maximum dimension 0.5*WSEN along the measurement axis direction MA. If the position of the signal modulating element SME (e.g., a conductive plate) proximate to the sensing portion PRTSEN changes continuously along the measurement axis direction MA, the alternating current (AC) amplitude of the signal output from the sensing portion PRTSEN changes continuously and periodically with the wavelength WSME due to the periodic changes of the sensing elements SEN+ and SEN- and the local disturbance of the transmit magnetic field caused by the signal modulating element SME. Thus, the signal output from the sensing portion PRTSEN can be utilized (e.g., processed) to indicate the relative position between the detector portion 167' and the scale 170'.

[0020] In operation, an alternating current may be provided, but to simplify certain parts of the description herein, only one direction of current is described (e.g., as an example of one direction of current and / or as may occur in configurations where diodes or other components / configurations are provided to restrict the current flow to one direction). As an example, a current (e.g., provided by a magnetic field generating drive signal, such as from the processing unit 166, and / or controlled by the processing unit 166) may flow from terminal "IN" to terminal "OUT" through the magnetic field generating winding of the magnetic field generating unit PRTFGE. More specifically, this indicates a current flow in a clockwise direction, which generates a corresponding magnetic flux, for example, in an internal region aligned with the sensing unit PRTSEN. As described above, such a current flow (with the resulting magnetic flux, for example, as affected by the signal modulation element SME) results in a signal being generated at the sensing elements SEN+ and SEN- in the sensing unit PRTSEN.

[0021] As an example of how the inductive encoder 101 operates, when the scale 170' and its signal modulating element SME move relative to the detector portion 167' (e.g., corresponding to the movement of the detector portion 167' relative to the scale 170' or vice versa), the signal modulating element SME alternately covers or is positioned adjacent to all the "+" loops of the sensing element SEN+ or all the "-" loops of the sensing element SEN-. In the position shown in FIG. 2, the signal modulating element SME is adjacent to or "overlaps" (e.g., is aligned with) all of the "-" loops of the sensing element SEN- in the sensing portion PRTSEN. When the magnetic field generating winding of the magnetic field generating portion PRTFGE inductively couples to the signal modulating element SME and induces eddy currents in the signal modulating element SME, the signal modulating element SME generates a magnetic field that counteracts the magnetic field passing through the sensing element SEN-. Thus, the sensing element SEN- generates less induced electromagnetic field (EMF) than the sensing element SEN+, which fully receives magnetic flux from the magnetic field. As a result, in this example, the sensing portion PRTSEN produces a net "positive" polarity EMF, current, and / or voltage at its output. The output signal varies over time because the magnetic field generating portion PRTFGE produces a time-varying magnetic field. The amplitude and polarity of the time-varying output signal relative to the input signal provides an indication of position between the detector portion 167' and the scale 170'.

[0022] Alternatively, when the scale 170′ is moved (not shown) so that the signal modulating element SME overlaps (e.g., is aligned) with the “+” loop of the sensing element SEN+, the induced current generated in the signal modulating element SME cancels the magnetic flux of the magnetic field passing through the “+” loop of the sensing element SEN+. As a result, the sensing element SEN− generates more induced EMF than the sensing element SEN+. As a result, the sensing portion PRTSEN generates a net “negative” polarity EMF, current, and / or voltage at its output.

[0023] In one example, the circuitry of the processing unit 166 may be connected to a terminal V + and V -, which samples changes in the signal (e.g., changes in voltage or current) output from the sensing portion PRTSEN, thereby calculating the linear position / distance of the detector portion 167' along the scale 170'. Although FIG. 2 shows a single set of sensing elements for simplicity and to avoid visual clutter, in various implementations, as will be understood by those skilled in the art, the sensing portion PRTSEN includes one or more additional sets of sensing elements (e.g., similar to SETSEN as shown) at different spatial phase positions (e.g., to provide orthogonal signals). Additionally, in various implementations, one or more additional scale tracks (e.g., pattern portions) are included as part of the scale 170, along with one or more additional corresponding sets of sensing elements of the sensing portion PRTSEN. For example, in some implementations, the scale tracks may have a spatial phase offset with respect to one another, or the wavelength of each scale track set may be different from WSME and WSEN, and processing of the combined signal may provide an absolute measurement, etc. Particular examples of such principles are described in part in US Pat. Nos. 9,772,202 and 11,713,983, each of which is incorporated herein by reference in its entirety.

[0024] It will also be understood that the sensing element configurations described herein are exemplary only and not limiting. As an example, each sensing element loop may output an individual signal to a corresponding processing unit in some implementations, as disclosed, for example, in U.S. Pat. No. 9,958,294, which is incorporated herein by reference in its entirety. More generally, in various implementations, various known sensing element configurations may be used in combination with the principles disclosed and claimed herein for use in combination with various known scale patterns and signal processing schemes. In connection with such implementations, it will be understood that references herein to processing detector signals from a sensing portion PRTSEN of the detector portion 167 (e.g., to determine relative position) may include processing and / or combining signals from different sets SETSEN of sensing elements (e.g., in quadrature and / or from different scale tracks and / or as part of a three-phase or four-phase system, etc.).

[0025] The scale 170 and the detector section 167 and / or other elements described herein can be easily manufactured by conventional techniques. For example, the detector section 167 can be manufactured using known printed circuit board (PCB) techniques (on rigid or flexible substrates) by forming the magnetic field generating section PRTFGE and the sensing section PRTSEN (e.g., including its windings) on a PCB substrate. Appropriate insulators and / or elements or parts of different elements on different layers of the PCB may be included at the transition points between the "+" and "-" loops of the sensing elements SEN+ and SEN-, and the set of sensing elements SESTSEN crosses over itself to prevent shorting of the windings at the transition or crossover points. Similarly, the scale 170 can be manufactured using known PCB techniques by forming the signal modulating elements SME on a PCB substrate.

[0026] According to standard PCB manufacturing processes, "vias" may be utilized for connections between different layers of a PCB (e.g., vias may also be known as "plated through holes" or "through vias" in some cases in a PCB). As shown in FIG. 2, the terminal V + and V - There are two vias SN+ and SN- connected to the terminal V of the set SETSEN of the sensing element. The vias SN+ and SN- are correspondingly referred to as "sensor vias" in this specification. The signal lines SIG+ and SIG- are connected to the terminal V of the set SETSEN of the sensing element. + and V - are connected to sensor vias SN+ and SN−, which are then connected to processing unit 166 (e.g., electronics may be included on a different layer of the PCB relative to the layer containing the set of sensing elements SETSEN, and thus sensor vias SN+ and SN− provide the necessary connections between the different layers of the PCB).

[0027] As will be described in more detail below, in various implementations, some of the connections from the set of sensing elements SETSEN to the processing unit 166, particularly some of the connections to and from the sensor vias SN+ and SN-, may form a parasitic loop (e.g., a "parasitic sensor loop"). An example of such a parasitic sensor loop LSN-A is described in more detail below with respect to FIG. 3. As will be described in more detail below, any current induced in such a parasitic sensor loop may result in an offset signal that introduces an error into the position calculation / determination of the inductive encoder 101.

[0028] More specifically, as described above, in the case of ideal inductive encoder operation, detector signals are generated based on the interaction of the signal modulating element SME of the scale 170 with the magnetic field / flux generated by the magnetic field generating unit PRTFGE and sensed by the sensing element (e.g., part of the set of sensing elements SETSEN). These signals correspondingly provide a very accurate indication of the position of the detector unit 167 relative to the scale 170. However, if a "stray magnetic field" induces a current in a parasitic sensor loop (e.g., as described above), it can result in an offset signal in the detector signal received by the processing unit 166, which can result in an error in the position calculation / determination of the inductive encoder 101. As described in more detail below (e.g., with respect to Figures 5 and 6), in some cases, such a stray magnetic field can be generated by a current through a "magnetic field generating via" (i.e., a via utilized for connection between different layers of the PCB for the magnetic field generating unit PRTFGE). As will be further described in more detail below with respect to Figures 4-13, in accordance with the principles disclosed herein, to reduce the effects of such problems, a shielding structure including a shielding via (e.g., utilized to form a shielding loop) is provided located proximate to the sensor via (e.g., to provide a particular shielding effect, etc.).

[0029] 3 illustrates the connections from four sets of sensing elements SETSEN-A, SETSEN-B, SETSEN-C and SETSEN-D to four sets of sensor vias SSN-A (including two sensor vias SN1A / SN2A), SSN-B (including two sensor vias SN1B / SN2B), SSN-C (including two sensor vias SN1C / SN2C) and SSN-D (including two sensor vias SN1D / SN2D). A larger set of sensor vias SSN-AB combines the two sets of sensor vias SSN-A and SSN-B to include four sensor vias SN1A / SN2A and SN1B / SN2B. A larger set of sensor vias SSN-CD combines the two sets of sensor vias SSN-C and SSN-D to include four sensor vias SN1C / SN2C and SN1D / SN2D. Signal lines SIG-A, SIG-B, SIG-C, and SIG-D carry signals from the sets of sensing elements SETSEN-A, SETSEN-B, SETSEN-C, and SETSEN-D included in the sensor portion PRTSEN' to the four sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D. Connections CON166 are signal lines from the four sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D to a processing unit (e.g., processing unit 166), and these connections may form a parasitic loop (e.g., a parasitic sensor loop).

[0030] Specifically, the connections CON166 to and from the sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D to the processing unit 166 may form a parasitic sensor loop (e.g., currents may be induced by a "stray magnetic field," as described in more detail below). As an example of such a parasitic sensor loop, the parasitic sensor loop LSN-A is shown in FIG. 2 in dashed lines, with at least a portion of the interior of the parasitic sensor loop LSN-A shown in hatching. As shown, the parasitic sensor loop LSN-A includes at least a first set of sensor vias SSN-A (including two sensor vias SN1A and SN2A), such as a portion of the connections CON166 to the processing unit 166. Although only one parasitic sensor loop LSN-A is shown, it should be understood that additional parasitic sensor loops LSN-B, LSN-C, and LSN-D may be similarly formed based on the connections CON166 from the other sets of sensor vias SSN-B, SSN-C, and SSN-D to the processing unit 166. Any current induced (e.g., introduced by stray magnetic fields) in such a parasitic sensor loop LSN-A or the like may result in an offset signal that may introduce errors in the position calculation / determination of the inductive encoder 101. As described in more detail below, to address such issues, a shielding structure (e.g., at least partially shielding the sensor vias) may be provided to help prevent / reduce currents from being induced in the parasitic sensor loop.

[0031] Fig. 4 illustrates a shield structure SST arranged in proximity to a set of sensor vias SSN (such as the set of sensor vias SSN shown in Figs. 3 and 6) configured according to an embodiment of the present invention. Fig. 4 illustrates three shield structures SST-A, SST-B, and SST-C arranged in proximity to the sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D and configured to at least partially shield the sensor vias SN included in those sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D (e.g., to at least partially shield the sensor vias from stray magnetic fields that may induce currents in parasitic sensor loops including the sensor vias). Each shield structure SST comprises a number of shield vias SH, and in each shield structure SST, one or more shield loops SL are formed by a number of shield vias SH coupled to each other by conductor parts CP such that currents (e.g., eddy currents) can flow in the loops through each of the shield loops SL (e.g., as part of the shielding function to effectively shield the sensor vias).

[0032] Specifically, in FIG. 4, the first shield structure SST-A is disposed adjacent to the set of sensor vias SSN-AB, and includes three shield vias SH1A, SH2A, and SH3A to form first and second shield loops SL1A and SL2A. The first shield loop SL1A is formed by the shield vias SH1A and SH2A coupled to each other by a first conductor portion CP1A (indicated by a dashed line) near the top of the shield vias SH1A and SH2A and a second conductor portion CP2A near the bottom of the shield vias SH1A and SH2A. This allows a current to flow in a loop shape as shown by a current flow (arrow) CF1A through the first shield loop SL1A. Similarly, the second shield loop SL2A is formed by the shield vias SH2A and SH3A coupled to each other by a third conductor portion CP3A (indicated by a dashed line) near the top of the shield vias SH2A and SH3A and a fourth conductor portion CP4A near the bottom of the shield vias SH2A and SH3A. This allows current to flow in a loop as shown by current flow (arrow) CF2A through the second shield loop SL2A. The first and third conductor portions CP1A and CP3A (shown as dashed lines) may be formed in the ground layer or another layer of the PCB used to form the detector portion 167, as described in more detail below with reference to other figures. For ease of explanation, the ground layer (or other layers corresponding to the first and third conductor portions CP1A and CP3A and other odd-numbered conductor portions described below) are not explicitly shown in Figure 4, although similar layers are shown in Figures 8 and 9, as described in more detail below.

[0033] The second shield structure SST-B is disposed adjacent to (and between) the sensor via set SSN-AB and the sensor via set SSN-CD, includes two shield vias SH1B and SH2B, and forms one shield loop SL1B. The shield loop SL1B is formed by the shield vias SH1B and SH2B coupled to each other by a fifth conductor portion CP1B (shown as a dashed line) near the top of the shield vias SH1B, SH2B and a sixth conductor portion CP2B near the bottom of the shield vias SH1B and SH2B. As a result, a current may flow in a loop, forming a current flow (not shown) through the shield loop SL1B. The fifth conductor portion CP1B (shown as a dashed line) may be formed in the ground layer or another layer of the PCB used to form the detector portion 167, as described in more detail below.

[0034] The third shield structure SST-C is disposed adjacent to the set of sensor vias SSN-CD and includes three shield vias SH1C, SH2C, and SH3C to form first and second shield loops SL1C and SL2C. The first shield loop SL1C is formed by the shield vias SH1C and SH2C coupled to each other by a seventh conductor portion CP1C (shown by a dashed line) near the top of the shield vias SH1C and SH2C and an eighth conductor portion CP2C near the bottom of the shield vias SH1C and SH2C. This allows a current to flow in a loop and form a current through the first shield loop SL1C. Similarly, the second shield loop SL2C is formed by the shield vias SH2C and SH3C coupled to each other by a ninth conductor portion CP3C (shown by a dashed line) near the top of the shield vias SH2C and SH3C and a tenth conductor portion CP4C near the bottom of the shield vias SH2C and SH3C. This may cause the current to flow in a loop, forming a current through the second shield loop SL2C. The seventh and ninth conductor portions CP1C and CP3C (shown as dashed lines) may be formed on the ground layer or another layer of the PCB used to form the detector portion 167, as described in more detail below.

[0035] In various exemplary embodiments, in the presence of a stray magnetic field (e.g., resulting from vertical current flow in the vertical magnetic field generating vias, described in more detail below), eddy currents are induced to flow in the shield loops SL1A, SL2A, SL1B, SL1C, and SL2C of the shield structures SST-A, SST-B, and SST-C. Such eddy currents thus cancel the stray magnetic field and prevent it from undesirably coupling into the parasitic sensor loop LSN-A, etc. (e.g., as part of the shielding function to at least partially shield a sensor via that is part of the parasitic sensor loop).

[0036] FIG. 5 is a top view of the configuration of FIG. 4, showing the current through the magnetic field generating via FG1 (eg, as further illustrated in FIG. 6).

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[0042]

number

[0043]

number

[0044]

number

[0045] In certain implementations, at least some of the sensor vias SN (e.g., sensor vias SN in a set of SSN-A, SSN-B, SSN-C, or SSN-D) adjacent to the shield structures SST-A, SST-B, and SST-C are in a linear arrangement extending in a direction perpendicular to the measurement axis direction MA (e.g., parallel to the x-axis direction). According to some implementations, a distance length DL2 of the linear arrangement of shield vias of the shield structures SST-A, SST-B, or SST-C is at least as long as a distance length DL1 of the linear arrangement of sensor vias in the SSN-A, SSN-B, SSN-C, or SSN-D adjacent to the shield structures SST-A, SST-B, or SST-C.

[0046] In various implementations, it may be considered advantageous for a shielding structure SST to generally have fewer shielding vias SH and more corresponding shielding loops SL (e.g., this may be more effective in shielding with respect to the local strength of the magnetic field, and the total number may also be limited by some practical considerations, such as constraints / requirements of the PCB manufacturing process, etc.). For example, as shown in FIG. 5, in the third shielding structure SST-C, the first shielding loop SL1C formed by the lower and middle shielding vias (e.g., SH1C and SH2C in FIG. 4) is closer to the magnetic field generating via FG1 and the magnetic field is smaller than the second shielding loop SL2C formed by the upper and middle shielding vias (e.g., SH3C and SH2C in FIG. 4) that are further away from the magnetic field generating via FG1, as shown in FIG. 5.

[0047]

number

[0048] FIG. 6 is an isometric view of an implementation of a transducer TDR″ including a detector portion 167″ and a scale 170″ (which may be, for example, a particular implementation of the transducer TDR, detector portion 167, and scale 170 as described above with respect to FIG. 1). FIG. 6 also shows a magnetic field generating via FG (for example, in an arrangement similar to that of FIG. 4 and FIG. 5) along with a shielding structure SST arranged adjacent to the set of sensor vias SSN. The configuration of the shielding structures SST-A, SST-B, SST-C arranged adjacent to the sets of sensor vias SSN-AB and SSN-CD in FIG. 6 is similar to that of FIG. 4 and FIG. 5, and therefore a detailed description thereof will not be repeated.

[0049] It will be understood that certain aspects of the magnetic field generating elements (e.g., layers) and sensing elements (e.g., layers) of a detector portion (e.g., detector portion 167") as described herein may operate and be understood at least in part based on the principles as described above with respect to FIG. 2. In the implementation of FIG. 6, the scale 170", detector portion 167" and processing portion 166 (e.g., of FIG. 1) cooperate to provide an inductive encoder (e.g., inductive encoder 101) that can be used to measure the relative position between two elements (e.g., between detector portion 167" and scale 170" and / or elements attached thereto) along the measurement axis direction MA.

[0050] In various implementations, the scale 170" extends along a measurement axis direction MA (e.g., corresponding to the x-axis direction) and includes a first signal modulating element SME1 and a second signal modulating element SME2. The first signal modulating element SME1 is arranged along the measurement axis direction MA according to, and thus forms, a first scale pattern portion 180-1. The second signal modulating element SME2 is arranged along, and thus forms, the measurement axis direction MA according to, and thus forms, a second scale pattern portion 180-2. The first scale pattern portion 180-1 and the second scale pattern portion 180-2 are respective parts of a periodic scale pattern 180" of the scale 170". In various implementations, the first and second signal modulating elements SME1 and SME2 may have a spatial phase offset with respect to each other and, in various implementations, may be arranged according to the same wavelength or different wavelengths (e.g., according to an intended interaction with a set of sensing elements of the sensing portion PRTSEN", as will be understood by one of ordinary skill in the art). In various implementations, the periodic scale pattern 180'' may alternatively be referred to as a signal modulation pattern 180''.

[0051] Relative movement between the detector portion 167" and the scale 170" indicates a relative position and / or measurement (e.g., relative to a physical element that may be coupled to the detector portion 167" or the scale 170", such as a first and second object or portion to determine a relative position between the first and second objects or portions, or a first and second jaw (e.g., of a caliper), or other measuring element between which an object may be placed to measure a dimension of the object). The measured relative position or dimension may be displayed on a display (e.g., digital display 138 of FIG. 1). Inductive encoders may also include various known elements (e.g., physical mounting and / or motion elements, etc.) configured to guide movement (e.g., for sliding, etc.) of the detector portion 167" relative to the scale 170".

[0052] As shown in FIG. 6, the detector section 167″ may include a magnetic field generating section PRTFGE″ and a sensing section PRTSEN″ arranged along the measurement axis direction MA. In the example of FIG. 6, the sensing section PRTSEN″ includes four sets of sensing elements, each of which provides detector signals on a respective set of signal lines including the illustrated set of signal lines SIG-A, SIG-B, SIG-C, and SIG-D that couple to corresponding sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D. The signal lines SIG-A, SIG-B, SIG-C, and SIG-D and the corresponding sets of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D may be equivalent to those shown in FIGS. 3-5 and have similar connections.

[0053] Each set of signal lines SIG-A, SIG-B, SIG-C, and SIG-D may also be equivalent to the set of signal lines SIG+ and SIG- shown in FIG. 2. For example, for a first set of sensing elements in the sensing unit PRTSEN'', the corresponding set of signal lines SIG-A may include a SIG+ signal line and a SIG- signal line that are respectively coupled to the V+ and V- terminals of the first set of sensing elements. Similarly, for a second set of sensing elements in the sensing unit PRTSEN'', the corresponding set of signal lines SIG-B may include a SIG+ signal line and a SIG- signal line that are respectively coupled to the V+ and V- terminals of the second set of sensing elements, and similarly for the third and fourth sets of sensing elements having corresponding sets of signal lines SIG-C and SIG-D. In various implementations, in the sensing portion PRTSEN'', different sets of sensing elements may have spatial phase offsets relative to each other (e.g., in an orthogonal arrangement and / or as a four-phase system, etc., as will be understood by those skilled in the art and described in more detail in the incorporated references).

[0054] In various implementations, such a configuration may allow for determining an absolute position (e.g., of the sensing portion PRTSEN″ of the detector portion 167″) along the measurement axis direction MA relative to the scale 170″. Such determination / calculation may involve processing (e.g., by the processing portion 166) of detector signals provided by the detector portion 167″ (e.g., including detector signals provided by the sensing portion PRTSEN″ via a set of signal lines SIG-A, SIG-B, SIG-C, and SIG-D that are coupled to a set of sensor vias SSN-A, SSN-B, SSN-C, and SSN-D that are coupled / providing signals to the processing portion 166). As will be explained in more detail below, according to the principles described herein, the shielding structure SST can be utilized to reduce the effects of stray magnetic fields (e.g., generated by currents passing through the magnetic field generating vias, such as vias FG1-FG8), which may result in certain offset signals to the detector signal from the sensing unit PRTSEN″ and may result in certain errors in the position determination / calculation based on the detector signal from the sensing unit PRTSEN″. The current flow through the magnetic field generating vias FG1-FG8 and the corresponding stray magnetic fields are explained in more detail below in connection with the operation of the magnetic field generating unit PRTFGE″.

[0055] In various implementations, the magnetic field generating portion PRTFGE" may include several elongated portions FGE1 to FGE4 and ends ED1 to ED4. The elongated portions FGE may generally extend along the measurement axis direction MA (e.g., correspondingly the x-axis direction) and thus be parallel, while the ends ED may generally be transverse (e.g., perpendicular) to the measurement axis direction MA (e.g., intersecting the x-axis direction such that the ends ED may extend along the y-axis direction). The elongated portions FGE and ends ED may combine to form a region in which a magnetic flux that varies due to a current through the elongated portions FGE and ends ED resulting from the drive signal may be generated, and the region (e.g., an inner region) may include some of the sensing elements.

[0056] For example, in various implementations, the magnetic field generating portion PRTFGE" may include elongated portions FGE1, FGE2, FGE3, and FGE4 and ends ED1, ED2, ED3, and ED4 (e.g., in some implementations, may be considered as forming two magnetic field generating element loops, such as a figure-of-eight configuration, and / or as a single magnetic field generating element loop forming two loops in a configuration forming two interior regions). More specifically, the elongated portions FGE1 and FGE2 and ends ED1 and ED4 may be considered as forming a first half loop having a first interior region configured to be aligned with the first half pattern portion 180-1 of the periodic scale pattern 180". The elongated portions FGE3 and FGE4 and ends ED2 and ED3 may be considered as forming a second half loop having an interior region configured to be aligned with the second half pattern portion 180-2 of the periodic scale pattern 180".

[0057] 6, magnetic field generating vias FG1-FG8 provide connections between elongated portion FGE and end ED. In various implementations, elongated portion FGE and end ED may be included on different layers of a printed circuit board (PCB) and / or at different vertical locations (e.g., to achieve certain desired operating characteristics, such as with respect to the magnetic field from a current flow through elongated portion FGE being closer to and having more interaction with signal modulating element SME and sensing element SEN than the magnetic field from a current flow through end ED). Magnetic field generating vias FG provide connections between the different layers / vertical locations.

[0058] In the example of Figure 6, end ED1 is coupled to elongated portions FGE1 and FGE2 by magnetic field generating vias FG2 and FG3, respectively. End ED2 is connected to elongated portions FGE2 and FGE3 by magnetic field generating vias FG4 and FG5, respectively. End ED3 is connected to elongated portions FGE3 and FGE4 by magnetic field generating vias FG6 and FG7, respectively. End ED4 is connected to elongated portions FGE1 and FGE4 by magnetic field generating vias FG1 and FG8, respectively.

[0059] In various implementations, the end ED2 (e.g., or other portions of the magnetic field generating portion PRTFGE″) may be represented as including a port PT1 or other connection configuration. For example, the end ED2 may be split into two portions, such as by providing two contact points at the port PT1 for the magnetic field generating portion PRTFGE″, as shown in FIG. 6 . The contacts in the port PT1 may be used to receive a drive signal, such as where a signal line / circuit trace from the processing portion 166 can connect. In various implementations, the port PT1 may represent a general connection configuration (e.g., between magnetic field generating vias FG4 and FG5), such as being coupled to magnetic field generating drive electronics. Such magnetic field generating drive electronics may include electronic components, such as capacitors, transistors, etc., in various implementations, and may be at least partially or completely included in or coupled to the processing portion 166 to provide a drive signal for causing the magnetic field generating portion PRTFGE″ to generate a changing magnetic flux. As described herein (e.g., with respect to FIG. 5 ), a corresponding current flowing through the magnetic field generating portion PRTFGE″ may be a function of a stray magnetic field (e.g., a stray magnetic field

[0060]

number

[0061]

number

[0062] Signal lines / circuit traces from processing unit 166 connect to magnetic field generating unit PRTFGE″ (not shown) (e.g., to provide a drive signal). In operation, an alternating current may be provided, although to simplify the following description, only one direction of current is described (e.g., as an example of one direction and / or as may occur in configurations where diodes or other components / configurations are provided to restrict current flow to one direction). As an example, a current (e.g., as provided by a drive signal) may flow through a series of portions (e.g., in the following order for current in one direction): magnetic field generating via FG1, elongated portion FGE1, magnetic field generating via FG2, end ED1, magnetic field generating via FG3, elongated portion FGE4, magnetic field generating via FG5, end ED6, magnetic field generating via FG6, end ED7, magnetic field generating via FG7, end ED8, magnetic field generating via FG8, end ED9, magnetic field generating via FG9, end ED10, magnetic field generating via FG11, end ED11, magnetic field generating via FG12, end ED12, magnetic field generating via FG13, end ED14, magnetic field generating via FG15, end ED15, magnetic field generating via FG16, end ED16, magnetic field generating via FG17, end ED18, magnetic field generating via FG19, end ED19, magnetic field generating via FG21, end ED19, magnetic field generating via FG22, end ED11, magnetic field generating via FG23, end ED11, magnetic field generating via FG24, end ED11, magnetic field generating via FG25, end ED11, magnetic field generating via FG26, end ED11, magnetic field generating via FG27, end ED11, magnetic field generating via FG28, end ED11, magnetic field generating via FG29, end ED12, magnetic field generating via FG31, end The elongated portion FGE2, magnetic field generating via FG4, end ED2, magnetic field generating via FG5, elongated portion FGE3, magnetic field generating via FG6, end ED3, magnetic field generating via FG7, elongated portion FGE4, magnetic field generating via FG8, and end ED4. According to this example of current flow, it will be understood that the current flow is in the same direction (e.g., a first direction along the x-axis / measurement axis direction MA) through the elongated portions at the outer boundaries of the configuration (i.e., elongated portions FGE1 and FGE3) and in the same direction (e.g., a second direction opposite to the first direction along the x-axis / measurement axis direction MA) through the elongated portions in the middle of the configuration (i.e., elongated portions FGE2 and FGE4) as may be desired for a particular implementation.

[0063] In various implementations, the detector portion 167" is mounted proximate to the periodic scale pattern 180" of the scale 170" and configured to move along the measurement axis direction MA relative to the periodic scale pattern 180" of the scale 170". In various implementations, the magnetic field generating portion PRTFGE" and the sensing portion PRTSEN" of the detector portion 167" may be formed according to a variety of alternative configurations used in combination with a variety of corresponding signal processing schemes, as will be appreciated by those skilled in the art.

[0064] It will be appreciated that various elements may be present on different fabrication layers located in different planes along the z-axis direction, as necessary, to provide various operating gaps and / or insulating layers, as would be apparent to one of ordinary skill in the art based on the description herein and the incorporated references. It will be appreciated that 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, and that they are not intended to contradict the various design principles and relationships described herein.

[0065] FIG. 7 illustrates a cross-sectional portion of a printed circuit board (PCB) including two shielding vias SH1A and SH2A that extend through six layers of the PCB. In various implementations, the illustrated portion may be a portion of an overall PCB, which may be referred to as a "detector substrate" on which a detector portion (e.g., detector portion 167" of FIG. 6) is formed. As shown in FIG. 7, the PCB includes six layers L1-L6, where each of the labeled layers L1-L6 is an electrical layer, and the layers between the labeled electrical layers L1-L6 are insulating layers. It will be understood that this configuration is intended to be illustrative only.

[0066] In various implementations, layers L1 and L2 comprise electronics layers and routing layers, respectively, and may include at least a portion of a processing unit that may be part of and / or otherwise coupled to processing unit 166 (FIG. 1) and / or may assist in providing and / or processing drive signals to the magnetic field generating unit PRTFGE″ and / or detector signals from the sensing unit PRTSEN″, etc. Layer L3 comprises a ground layer (GND) (e.g., for providing a ground layer (GND) or other common connection, etc.). Layer L4 comprises a magnetic field generating element layer that may include at least some of the elements / portions of the magnetic field generating unit (e.g., PRTFGE″ in FIG. 6). Layers L5 and L6 comprise a sensing element layer that may include at least some of the elements / portions of the sensing unit (e.g., PRTSEN″ in FIG. 6). In various implementations, layers L5 and L6 can include most or all of the set of sensing elements of sensing unit PRTSEN'', with different traces on different layers L5 and L6 (e.g., to provide electronic isolation at crossings, etc.), and connections between layers L5 and L6 for the sensing elements can be made by a particular type of via (e.g., a microvia that extends only between layers L5 and L6 and, in some implementations, may also be referred to as a blind via and / or a buried via).

[0067] As mentioned above, the particular diagram of FIG. 7 shows two shielding vias SH1A and SH2A extending through six layers L1-L6 of a PCB. According to a particular standard process, the vias may be made by a mechanical drill that drills holes through the layers of a printed circuit board, and the holes are then plated (e.g., with copper) to form the vias. According to particular design rules for PCBs, the vias, traces, and / or other components or elements must have a particular spacing between them, as well as other restrictions on particular types of geometric relationships, etc. It is noted that the shielding structure SST with the shielding vias SH disclosed herein may be formed according to such a standard process.

[0068] Unlike more typical vias (e.g., sensor via SN and magnetic field generating via FG) that are connected to other electronic circuits (e.g., connected to processing unit 166), in various implementations, the shield via SH and corresponding shield structure SST described herein are standalone independent elements and are not connected to other electronic circuits (e.g., processing unit 166) or are not part of a connection for signals from other electronic circuits. In one example, if shield vias SH1A and SH2A are each coupled to ground (e.g., layer L3 (GND)) to form an upper conductor portion CP1A (see FIG. 4) and each coupled to layer L4 to form a lower conductor portion CP2A (see FIG. 4), a corresponding shield loop SL1A is formed, and current can flow (e.g., in one particular exemplary direction) up the shield via SH1A, across layer L3, down the shield via SH2A, and across layer L4. In general, the conductor portions CP for coupling the shield vias SH to each other are included in a particular layer of the PCB, as further shown in FIG. 8 and FIG. 9 below.

[0069] In various implementations, it may be desirable for the shield loop SL to extend at least between layers L3 and L4. More specifically, in certain implementations, the distance between layers L3 and L4 may be relatively large (e.g., on the order of 1.0 mm), while the distance between layers L1 and L3 or between layers L4 and L6 may be relatively small (e.g., on the order of 0.1 mm, and for the above examples, certain z-axis dimensions of each layer as shown in FIG. 7, e.g., between L1 and L3 and between L4 and L6, are exaggerated for clearer illustration of each layer). In such examples, the relative distance (e.g., along the z-axis) between layers L3 and L4 (e.g., about 1.0 mm) may be more than 10 times the relative distance between layers L1 and L2, or between layers L2 and L3, or between layers L4 and L5, or between layers L5 and L6. In certain implementations where a parasitic loop (e.g., LSN-A) includes a connection between layer L1 and layer L5 or L6 and thus spans longer than the distance between layers L3 and L4, it may be desirable for the shield loop SL to span at least the greater distance between layers L3 and L4 in order to effectively shield at least a majority of the area of ​​the parasitic loop. As a particular example, when connecting shield via SH1A to shield via SH2A, if layer L3 (or L1 or L2) is selected to form upper conductor portion CP1A, it may be desirable for the lower conductor portion to be in at least layer L4 (or L5 or L6).

[0070] FIG. 8 is an isometric top view of the sets of sensor vias SSN-AB and SSN-CD along with the shielding structure SST of FIG. 6, in which the shielding vias SH of the shielding structure SST are shown coupled to each other by a conductor portion CP (e.g., an upper conductor portion) as part of a ground layer (e.g., layer L3 (GND)) of the PCB. Specifically, the upper conductor portion CP1A connecting the shield via SH1A and the shield via SH2A in the first shield structure SST-A, the upper conductor portion CP3A connecting the shield via SH2A and the shield via SH3A in the first shield structure SST-A as well, the upper conductor portion CP1B connecting the shield via SH1B and the shield via SH2B in the second shield structure SST-B, the upper portion CP1C connecting the shield via SH1C and the shield via SH2C in the third shield structure SST-C, and the upper portion CP3C connecting the shield via SH2C and the shield via SH3C in the third shield structure SST-C as well are all formed in the ground layer L3 (GND) in the illustrated example. In this example, technically, all the shield vias SH are coupled to each other on one side by the layer L3 (e.g., the ground layer L3) and coupled to each other on the other side by a conductor portion in another layer (e.g., the layer 4) to complete the shield loop SL as shown in FIG. 9.

[0071] 9 shows an isometric bottom view of the configuration of FIG. 8 (e.g., a view from below of the same layer L3 of FIG. 8), in which the shield vias SH of the shield structure SST are also shown coupled to each other by a conductor part CP (e.g., a lower conductor part) in a layer of the PCB different from the ground layer L3 (GND) (e.g., layer L4), thus forming a shield loop SL within the shield structure SST. Specifically, for each shield structure SST-A, SST-B, or SST-C, the multiple shield vias include at least a first shield via SH (e.g., SH1A) and a second shield via SH (e.g., SH2A), which are coupled to each other by a first conductor part CP (e.g., the upper conductor part CP1A of FIG. 8) and are coupled to each other by a second conductor part (e.g., the lower conductor part CP2A of FIG. 9). As a result, the first shield via (e.g., SH1A), the first conductor portion (e.g., CP1A), the second shield via (e.g., SH2A), and the second conductor portion (e.g., CP2A) form a first respective shield loop SL (e.g., SL1A) of one or more shield loops (e.g., SL1A and SL2A in FIG. 4). Similarly, lower conductor portions CP4A, CP2B, CP2C, CP4C may be formed on layer L4 to complete the other shield loops SL2A, SL1B, SL1C, SL2C, respectively.

[0072] 9, which may be provided in layer L4, may also or alternatively be referred to as "conductor straps." In an alternative implementation, assuming that the other (upper) conductor portions CP1A, CP3A, CP1B, CP1C, and CP3C of all shield vias SH are included in one of layers L1, L2, or L3 (e.g., in an upper portion of the PCB), conductor portions CP2A, CP4A, CP2B, CP2C, and CP4C may be included in one of the other layers L5 or L6 (e.g., in a lower portion of the PCB as explained above). In various implementations, the (upper) conductor portions CP1A, CP3A, CP1B, CP1C, and CP3C may also be formed as "conductor straps" (e.g., as included in one of layers L1 or L2, in which case not all of the shield vias SH are coupled to each other on one side by a layer such as ground layer L3).

[0073] 10 illustrates two shielding structures SST-A' and SST-B', each including four shielding vias SH in a linear arrangement (e.g., along the y-axis direction in FIG. 10) and disposed adjacent to either side of a set of sensor vias SSN'. In the illustrated example, the set of sensor vias SSN' includes a first set of sensor vias SSN-A' including two sensor vias and a second set of sensor vias SSN-B' also including two sensor vias, to which signal lines SIG' carry signals from respective sets of sensing elements (not shown).

[0074] Since each shielding structure SST' includes four shielding vias SH in the illustrated example, each shielding structure SST' may form at least three shielding loops SL. Specifically, in the first shielding structure SST-A', the first and second shielding vias SH1A, SH2A may be coupled to each other by the first and second conductor portions CP1A, CP2A to form a first shielding loop SL1A, the second and third shielding vias SH2A, SH3A may be coupled to each other by the third and fourth conductor portions CP3A, CP4A to form a second shielding loop SL2A, and the third and fourth shielding vias SH3A, SH4A may be coupled to each other by the fifth and sixth conductor portions CP5A, CP6A to form a third shielding loop SL3A. Similarly, in the second shield structure SST-B', the first and second shield vias SH1B, SH2B may be coupled to each other by the first and second conductor portions CP1B, CP2B to form a first shield loop SL1B, the second and third shield vias SH2B, SH3B may be coupled to each other by the third and fourth conductor portions CP3B, CP4B to form a second shield loop SL2B, and the third and fourth shield vias SH3B, SH4B may be coupled to each other by the fifth and sixth conductor portions CP5B, CP6B to form a third shield loop SL3B.

[0075] As shown in FIG. 10, at least some of the sets of sensor vias (e.g., sensor vias in the sets of SSN-A' and SSN-B') adjacent to the multiple shield structures SST-A' and SST-B' are in a linear arrangement extending in a direction perpendicular to the measurement axis direction MA (e.g., parallel to the x-axis direction). According to a specific implementation, the distance length (e.g., DL2) of the linear arrangement of the shield vias SH of the shield structures SST (e.g., SST-A', SST-B') is at least as long as the distance length (DL1) of the linear arrangement of the sensor vias (e.g., sensor vias in SSN') adjacent to the shield structures (e.g., SST-A' or SST-B'). In the specific example of FIG. 10, DL2 may be approximately equal to DL1, and a similar dimensional ratio (having approximately equal distance lengths) is shown in FIG. 11 below.

[0076] FIG. 11 is a diagram showing two shielding structures SST-A″ and SST-B″, each including six shielding vias SH in a linear arrangement (e.g., along the y-axis direction). The two shielding structures SST-A″ and SST-B″ are positioned adjacent to and on either side of a sensor via set SSN″ including six sensor vias in a linear arrangement, with signal lines SIG″ carrying signals from a respective set of sensing elements (not shown).

[0077] In this example, since each shielding structure SST″ includes six shielding vias SH1 to SH6, each structure SST″ has the potential to form at least five shielding loops SL. Specifically, in the first shielding structure SST-A″, the first and second shielding vias SH1A, SH2A are connected to each other by upper and lower conductor portions CP to form a first shielding loop SL1A, the second and third shielding vias SH2A, SH3A are connected to each other by upper and lower conductor portions CP to form a second shielding loop SL2A, the third and fourth shielding vias SH3A, SH4A are connected to each other by upper and lower conductor portions CP to form a third shielding loop SL3A, the fourth and fifth shielding vias SH4A, SH5A are connected to each other by upper and lower conductor portions CP to form a fourth shielding loop SL4A, and the fifth and sixth shielding vias SH5A, SH6A are connected to each other by upper and lower conductor portions CP to form a fifth shielding loop SL5A. Similarly, In the second shield structure SST-B″, the first and second shield vias SH1B, SH2B may be coupled to each other by upper and lower conductor portions CP to form a first shield loop SL1B, the second and third shield vias SH2B, SH3B may be coupled to each other by upper and lower conductor portions CP to form a second shield loop SL2B, the third and fourth shield vias SH3B, SH4B may be coupled to each other by upper and lower conductor portions CP to form a third shield loop SL3B, the fourth and fifth shield vias SH4B, SH5B may be coupled to each other by upper and lower conductor portions CP to form a fourth shield loop SL4B, and the fifth and sixth shield vias SH5B, SH6B may be coupled to each other by upper and lower conductor portions CP to form a fifth shield loop SL5B.

[0078] FIG. 12 is a diagram showing two shielding structures SST'' in a box arrangement, each of which surrounds a set of sensor vias SSN arranged similarly to FIG. 4 to FIG. 6. Specifically, the first box arrangement SST-AB'' is formed from a first shielding structure SST-A''' in which two shielding vias SH1A and SH2A are coupled to each other by an upper conductor portion CP1A'''' and a lower conductor portion CP2A'''' to form a first shielding loop SL1A having a current loop CL1A (e.g., parallel to the YZ plane of the coordinate system), and a second shielding structure SST-B'''' in which two shielding vias SH1B and SH2B are coupled to each other by an upper conductor portion CP1B'''' and a lower conductor portion CP2B'''' to form a second shielding loop SL1B having a current loop CL1B (e.g., parallel to the YZ plane). Furthermore, in the first box arrangement SST-AB''', the first and second shield structures SST-A''' and SST-B''' are coupled to each other by upper conductor portions CP1AB''' and CP3AB''' and lower conductor portions CP2AB''' and CP4AB''' to form third and fourth shield loops SL1AB and SL2AB having current loops CL1AB and CL2AB (e.g., parallel to the XZ plane).

[0079] In certain implementations, the shield current flowing in the XZ plane (e.g., through current loops CL1AB and CL2AB) may distort the magnetic field passing through scale 170 in the XY plane (e.g., in accordance with the operations described above in Figures 2 and 6), changing the quality / accuracy of the detector signal, in which case the box arrangement SST-AB''' may be considered less desirable than other configurations of shield structure SST described above. Alternatively, in certain implementations, it may be desirable for the shield current to flow in the XZ plane (e.g., through current loops CL1AB and CL2AB), in which case the box arrangement SST-AB''' may be considered more desirable.

[0080] Similar to the first box arrangement SST-AB'''', the second box arrangement SST-CD''' is formed from a first shielding structure SST-C''' in which two shielding vias SH1C and SH2C are coupled to each other by an upper conductor portion CP1C'''' and a lower conductor portion CP2C'''' to form a first shielding loop SL1C having a current loop CL1C (e.g., parallel to the YZ plane of the coordinate system), and a second shielding structure SST-D'''' in which two shielding vias SH1D and SH2D are coupled to each other by an upper conductor portion CP1D'''' and a lower conductor portion CP2D'''' to form a second shielding loop SL1D having a current loop CL1D (e.g., parallel to the YZ plane). Furthermore, in the second box arrangement SST-CD'''', the first and second shield structures SST-C'''' and SST-D'''' are coupled to each other by upper conductor portions CP1CD'''' and CP3CD'''' and lower conductor portions CP2CD'''' and CP4CD'''' to form third and fourth shield loops SL1CD and SL2CD having current loops CL1CD and CL2CD (e.g., parallel to the XZ plane).

[0081] In the first and second box arrangements SST-AB''', SST-CD''', the shield current may further flow in the XY plane, for example, through upper conductor portions CP1A''', CP1AB''', CP1B''', and CP3AB''', or through lower conductor portions CP2A''', CP2AB''', CP2B''', and CP4AB''', or through upper conductor portions CP1C''', CP1CD''', CP1D''', and CP3CD''', or through lower conductor portions CP2C''', CP2CD''', CP2D''', and CP4CD'''. As with potential currents flowing in the XZ plane, in various implementations potential currents flowing in the XY plane may be deemed more or less desirable.

[0082] 13 is a flow diagram illustrating a routine 1300 for operating an inductive encoder system that may be configured as described in detail above. The method generally includes three steps. In block 1310, a first step includes providing a drive signal to generate a varying magnetic flux to a magnetic field generating portion PRTFGE of a detector portion 167 of an inductive encoder 101. Operation of the magnetic field generating portion PRTFGE generates one or more stray magnetic fields, and the detector portion 167 includes a sensing portion PRTSEN that includes one or more sets SETSEN of sensing elements arranged along a measurement axis direction MA. Each set SETSEN of sensing elements is coupled to a set of sensor vias SN, and the detector portion 167 is configured to move along the measurement axis direction MA relative to a scale 170 that includes a signal modulating element SME.

[0083] In block 1320, the second step includes receiving a detector signal from the sensing unit PRTSEN, where at least one set of sensor vias SN are at least partially shielded from one or more stray magnetic fields by a plurality of shield structures SST. For example, at least some sensor vias SN of the at least one set of sensor vias SSN form at least a part of one or more parasitic loops, and the shield of the at least one set of sensor vias SSN reduces an offset signal portion in the detector signal resulting from one or more stray magnetic fields coupling to one or more parasitic loops in the absence of the shield structure SST.

[0084] In block 1330, a third step includes determining a relative position between the detector portion 167 and the scale 170 based at least in part on the detector signal. To this end, the multiple shield structures SST may be configured such that the determined relative position does not include at least a portion of the position error caused by the offset signal portion that would occur in the absence of the shield structure SST.

[0085] It will be appreciated that the principles disclosed and claimed herein may be readily and desirably combined with various features disclosed in the incorporated references. The various implementations described above may be combined to provide further implementations. All U.S. patents and U.S. patent applications referenced herein are incorporated herein by reference in their entirety. Aspects of the implementations may be modified, if necessary, to use concepts from the various patents and applications to provide further implementations. These and other changes can be made to the implementations in light of the above detailed description. In general, the terms used in the following claims should not be construed to limit the scope of the claims to the specific implementations disclosed in the specification and claims, but should be construed to include all possible implementations along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. An inductive encoder system configured to measure a relative position between two elements along a measurement axis, the system comprising: a scale extending along the measurement axis direction, the scale including a periodic scale pattern including signal modulating elements; a detector portion disposed proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern, the detector portion comprising: A magnetic field generating unit PRTFGE configured to generate a magnetic flux that changes in response to a drive signal; A sensing portion P having one or more sets of sensing elements arranged along the measurement axis direction. a detector portion comprising: a sensing portion PRTSEN, each set of sensing elements coupled to a set of sensor vias, the sensing portion PRTSEN configured to provide a detector signal responsive to a local effect on the changing magnetic flux provided by an adjacent signal modulating element of the periodic scale pattern; a plurality of shielding structures SST, each of which is disposed adjacent to a set of sensor vias and includes a plurality of shielding vias, and in each of the shielding structures SST, one or more shielding loops are formed by the plurality of shielding vias coupled to each other by conductor portions; 1. An inductive encoder system comprising:

2. 2. The system of claim 1, wherein for each shielding structure SST, the plurality of shielding vias includes at least a first shielding via and a second shielding via, the first shielding via and the second shielding via are coupled to each other by a first conductor portion and coupled to each other by a second conductor portion, and the first shielding via, the first conductor portion, the second shielding via, and the second conductor portion form a first respective shielding loop of the one or more shielding loops.

3. 3. The system of claim 2, wherein for one or more shielding structures SST of the plurality of shielding structures SST, the plurality of shielding vias comprises at least a third respective shielding via, the third respective shielding via being coupled to the second shielding via by a third conductor portion and coupled to the second shielding via by a fourth conductor portion, and the second shielding via, the third conductor portion, the third shielding via, and the fourth conductor portion form a second respective shielding loop of the one or more shielding loops.

4. The system of claim 3 , wherein for each shielding structure SST, the plurality of shielding vias are in a linear arrangement.

5. 3. The system of claim 2, wherein the first conductor portion is in a first layer of a printed circuit board and the second conductor portion is in a second layer of the printed circuit board.

6. The system of claim 1 , wherein the plurality of shielding structures SST includes at least a first shielding structure and a second shielding structure.

7. The system of claim 6 , wherein the first shielding structure SST and the second shielding structure SST are disposed on either side of a set of sensor vias including at least two sensor vias.

8. The system of claim 6 , wherein the first shield structure SST and the second shield structure SST are disposed on either side of a set of sensor vias including at least four sensor vias.

9. The system of claim 1 , wherein the plurality of shielding vias are configured to at least partially shield the sensor via from one or more magnetic fields resulting from current flowing in one or more magnetic field generating vias.

10. The system of claim 1 , wherein each shield structure SST includes a linear arrangement of the plurality of respective shield vias extending in a direction perpendicular to the measuring axis direction.

11. The system of claim 10 , wherein at least some of the set of sensor vias adjacent to which the plurality of shielding structures SST are disposed are in a linear arrangement extending in a direction perpendicular to the measurement axis direction.

12. The system of claim 11 , wherein a linear arrangement of shielding vias of a first shielding structure (SST) is at least as long as a linear arrangement of sensor vias adjacent to said first shielding structure (SST).

13. 2. The system of claim 1, wherein the magnetic field generating portion PRTFGE comprises one or more magnetic field generating elements surrounding an internal region that is aligned with at least a portion of the periodic scale pattern of a signal modulating element during operation, the one or more magnetic field generating elements configured to generate the changing magnetic flux in the internal region in response to the drive signal.

14. The system of claim 13 , wherein each shield structure SST is configured to at least partially shield a proximate set of sensor vias from stray magnetic fields resulting from the operation of the magnetic field generating portion PRTFGE.

15. The system of claim 1 , wherein the members of the set of sensing elements comprise loops.

16. 2. The system of claim 1 , wherein the one or more sets of sensing elements comprise at least a first set of sensing elements and at least one additional set of sensing elements, each additional set of sensing elements having a spatial phase offset relative to the first set of sensing elements.

17. 1. A method of operating an inductive encoder system configured to measure a relative position between two elements along a measurement axis, comprising: The inductive encoder system comprises: a scale extending along the measurement axis direction, the scale including a periodic scale pattern including signal modulating elements; a detector portion disposed proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern, the detector portion comprising: A magnetic field generating unit PRTFGE configured to generate a magnetic flux that changes in response to a drive signal; A sensing portion P having one or more sets of sensing elements arranged along the measurement axis direction. a detector portion comprising: a sensing portion PRTSEN, each set of sensing elements coupled to a plurality of sensor vias, the sensing portion PRTSEN configured to provide a detector signal responsive to a local effect on the changing magnetic flux provided by adjacent signal modulating elements of the periodic scale pattern; a plurality of shielding structures (SST), each of which is disposed adjacent to a set of sensor vias and includes a plurality of shielding vias, and in each of the shielding structures (SST), one or more shielding loops are formed by the plurality of shielding vias coupled to each other by conductor portions; The method comprises: providing a drive signal to the magnetic field generating unit PRTFGE to generate the varying magnetic flux, the operation of the magnetic field generating unit PRTFGE generating one or more stray magnetic fields; receiving a detector signal from the sensing unit PRTSEN, wherein at least one set of sensor vias is at least partially shielded from the one or more stray magnetic fields by the plurality of shielding structures; determining a relative position between the detector portion and the scale based at least in part on the detector signal.

18. 18. The method of claim 17, wherein at least some of the at least one set of sensor vias form at least a portion of one or more parasitic loops, and the shielding of the at least one set of sensor vias reduces an offset signal portion in the detector signal that would result from the one or more stray magnetic fields coupling to the one or more parasitic loops in the absence of the shielding structure.

19. The method of claim 17 , wherein the relative position does not include position errors that would occur if the shield structure were not present.

20. 1. A detector section for use in an inductive encoder configured to measure a relative position between two elements along a measurement axis direction, the encoder including a scale extending along the measurement axis direction, the scale including a periodic scale pattern having signal modulating elements, the detector section being positioned proximate to the periodic scale pattern and configured to move along the measurement axis direction relative to the periodic scale pattern, the detector section comprising: A magnetic field generating unit PRTFGE configured to generate a magnetic flux that changes in response to a drive signal; A sensing portion P having one or more sets of sensing elements arranged along the measurement axis direction. a sensing portion PRTSEN, each set of sensing elements coupled to a plurality of sensor vias, the sensing portion PRTSEN configured to provide a detector signal responsive to a local effect on the changing magnetic flux provided by adjacent signal modulating elements of the periodic scale pattern; A detector portion comprising: a plurality of shielding structures SST, each of which is arranged adjacent to a set of sensor vias and includes a plurality of shielding vias, and in each of the shielding structures SST, one or more shielding loops are formed by the plurality of shielding vias coupled to each other by conductor portions.

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