Patent Description:
The invention is defined by a system according claim <NUM>.

Embodiments of the claimed invention are defined in the dependent claims <NUM>-<NUM>.

The foregoing features may be more fully understood from the following description of the drawings in which:.

<FIG> is a planar top-down view of a target strip <NUM>, according to aspects of the disclosure. The target strip <NUM> may include a first array <NUM> of conductive features <NUM>, and a second array <NUM> of conductive features <NUM>. The conductive features <NUM> may be arranged along a line L1-L1 and spaced apart from one another by voids <NUM>. The conductive features <NUM> may be arranged along a line L2-L2 and spaced apart from one another by voids <NUM>. Although lines L1-L1 and L2-L2 are straight lines in the present example, alternative implementations are possible in which they are curved. According to the present example, the conductive features <NUM> and <NUM> are made of metal and they are disposed on a substrate <NUM>. The substrate <NUM> may be formed of any suitable type of dielectric material. The substrate <NUM> may be either rigid or flexible. For example, the substrate may be a plastic film. Although in the present example, the conductive features <NUM> and <NUM> are disposed on the substrate <NUM>, alternative implementations are possible in which the conductive features <NUM> and <NUM> are integrated into the substrate <NUM>. In such implementations, the target strip <NUM> may be implemented as a printed circuit board (PCB).

Array <NUM> may include N conductive features <NUM>, where N is a positive integer greater than or equal to <NUM>. Array <NUM> may include N+I conductive features <NUM>, where I is an integer greater than or equal to <NUM>. As a result of this arrangement, the target strip <NUM> may include a greater number of conductive features <NUM> than conductive features <NUM>. Each of the conductive features <NUM> may have a width W1 and each of the conductive features <NUM> may have a width W3, where W3<W1. Each of the voids <NUM> may have a width W2 and each of the voids <NUM> may have a width W4. According to the present example, the width W2 is greater than the width W4. However, alternative implementations are possible in which the width W2 is less than or equal to the width W4. Preferably, in some implementations, W1 may be equal to W2 and W3 may be equal to W4. However, the present disclosure is not limited thereto.

In some implementations, the target strip <NUM> may be defined in accordance with the following equations: I=<NUM> and N*<NUM>*W1 = (N+<NUM>)*<NUM>*W3. Optionally, as noted above, W1 may be equal to W2 and W3 may be equal to W4. However, the present disclosure is not limited thereto. In other words, the widths of the conductive features in the target strip <NUM> may be such that the two sets of features (i.e., conductive features <NUM> and <NUM>) fit in the same length. As is discussed below, a target strip that includes N conductive features <NUM> and N+<NUM> conductive features <NUM>, and which complies with the above equations, may also include at least one of: (i) one or more additional conductive features <NUM> (full or partial), (ii) one or more additional conductive features <NUM> (full or partial), and (<NUM>) one or more additional voids <NUM> (full or partial) and one or more and one or more additional voids <NUM> (full or partial). Such additional conductive features and/or voids may be provided in order to prevent the coils from running off the edge of the target (which would cause edge effects). In other words, the additional features or voids may fall outside of the stroke of the of the target strip <NUM>. Ensuring the that the coils cannot run off the edge of the target strip <NUM> would, under most circumstances, improve the accuracy of measurements of the position of the target.

The conductive features <NUM> and <NUM> may extend from a first end region <NUM> of the target strip <NUM> to a second end region <NUM> of the target strip <NUM>. The conductive features <NUM> in the array <NUM> may be staggered with respect to the conductive features <NUM> in the array <NUM>, such that each conductive feature <NUM> is aligned with at least one conductive feature <NUM> and the void <NUM> that is immediately adjacent to the conductive feature <NUM>, and separates the conductive feature <NUM> from a neighboring conductive feature.

In one example, the conductive feature <NUM>-<NUM> (shown in <FIG>) is aligned with the conductive feature <NUM>-<NUM>, as well as the void <NUM> that separates conductive features <NUM>-<NUM> and <NUM>-<NUM>. As another example, the conductive feature <NUM>-<NUM> is aligned with the conductive features <NUM>-<NUM> and <NUM>-<NUM>, as well as the void <NUM> that separates conductive features <NUM>-<NUM> and <NUM>-<NUM>. As yet another example, the conductive feature <NUM>-<NUM> is aligned with the conductive feature <NUM>-<NUM>, as well as the void <NUM> that separates conductive features <NUM>-<NUM> and <NUM>-<NUM>. In the example of <FIG>, a given conductive feature <NUM> is aligned with a given conductive feature <NUM> if the given conductive feature <NUM> is depicted directly above at least a portion of the given conductive feature <NUM>. Similarly, in the example of <FIG>, a given conductive feature <NUM> is aligned with a given void <NUM>, if the given conductive feature <NUM> is depicted directly above at least a portion of the given void <NUM>. Moreover, in the example of <FIG>, a given conductive feature <NUM> may overlap with a given void <NUM> if the given conductive feature <NUM> is depicted directly below at least a portion of the given void <NUM>. In general, two conductive features <NUM> and <NUM> may be aligned when the receiving coil arrays <NUM> and <NUM> would sense, at the same time, reflected magnetic fluxes originating from those conductive features. Or put differently, two conductive features <NUM> and <NUM> may be aligned if they are capable of being positioned under the receiving coil arrays <NUM> and <NUM> (or the sensor <NUM>) at the same time.

In some respects, each of the conductive features <NUM> may be offset (along the width of the target strip <NUM>) to a different degree from its nearest conductive feature <NUM>. As a result of this arrangement, each location of the sensor <NUM> relative to the target strip <NUM>, would correspond to a different pair (M1, M2), where M1 is the reflected magnetic flux through the receiving coil array <NUM> and M2 is the reflected magnetic flux through the receiving coil array <NUM>. This in turn permits a one-to-one mapping between: (i) the location of the target <NUM> and (ii) the magnetic fluxes through the receiving coil arrays <NUM> and <NUM> and/or the pair of signals that are generated by the receiving coil arrays <NUM> and <NUM>.

<FIG> is a planar side view of the implementation of the target strip <NUM>, which is shown in <FIG> illustrates that the target strip <NUM> may be provided on either a rigid or flexible sheet of dielectric material. In instances in which the target strip <NUM> is provided on a flexible sheet of dielectric material, the target strip <NUM> may adhere to mechanical parts whose position is desired to be monitored in a way that conforms to the shape of the mechanical parts (e.g., see <FIG>. The conductive features <NUM> and <NUM> may be formed of metal and or any other suitable type of electrically conductive material. In other words, the conductive features <NUM> and <NUM> may be metal tabs that are formed by using etching, die-pressing, laser cutting, metal deposition, and/or any other suitable type of technique. By way of example, in some implementations, the conductive features <NUM> and <NUM> may be formed by taking a sheet of metal (e.g., metal foil or thicker metal sheeting) and stamping the conductive features <NUM> and <NUM> out of the metal sheet. Each of the voids <NUM> and <NUM> may be an empty space or it may be filled with another material (e.g., a dielectric material).

<FIG> show an example of another implementation of the target strip <NUM>, according to aspects of the disclosure. In the implementation shown in <FIG>, the target strip <NUM> includes a spine <NUM> and the conductive features <NUM> and <NUM> are integrally formed with the spine <NUM>. Furthermore, in the example of FIG. <NUM>, the target strip is freestanding - in other words, it is not disposed on a substrate (because the conductive features <NUM> and <NUM> are held together by the spine <NUM>). Although in the example of <FIG> the target strip <NUM> is freestanding, alternative implementations are possible in which the target strip <NUM> is built into a printed circuit board or otherwise mounted on a substrate. Although in the example of <FIG>, the spine <NUM> is integral with the conductive features, alternative implementations are possible in which it is not. <FIG> is a planar side view of the implementation of the target strip <NUM>, which is shown in <FIG> illustrates that the target strip <NUM> may appear as a comparatively thin and elongated structure from the side.

<FIG> is a top-down view of an example of a system <NUM>, according to aspects of the disclosure. As illustrated, the system <NUM> may include the target strip <NUM> and a position sensor <NUM>. The position sensor <NUM> may be an inductive position sensor. As illustrated in <FIG> and <FIG>, the position sensor <NUM> may include a receiving coil array <NUM>, a receiving coil array <NUM>, a transmitting coil <NUM>, a transmitting coil <NUM>, and a processing circuitry <NUM> (shown in <FIG>). The transmitting coil <NUM> and the receiving coil array <NUM> may be formed on a substrate <NUM>. The receiving coil array <NUM> may be disposed inside the transmitting coil <NUM>, as shown in <FIG>. The receiving coil array <NUM> may include a receiving coil <NUM> and a receiving coil <NUM>. The receiving coil <NUM> may be configured to have a sinusoidal response, and the receiving coil <NUM> may be configured to have a co-sinusoidal response. Although in the present example the coils have a sinusoidal and co-sinusoidal response, it will be understood that any set of receiving coils that produces orthogonal signals can be used. The transmitting coil <NUM> and the receiving coil array <NUM> may be formed on the substrate <NUM>. The receiving coil array <NUM> may be disposed inside the transmitting coil <NUM>, as shown in <FIG>. The receiving coil array <NUM> may include a receiving coil <NUM> and a receiving coil <NUM>. The receiving coil <NUM> may be configured to have a CO-sinusoidal response, and the receiving coil <NUM> may be configured to have a sinusoidal response.

In operation, the sensor <NUM> may be positioned over the target strip <NUM>, such that substrate <NUM> is substantially parallel to the top surface <NUM> of the target strip <NUM>. The target strip <NUM> may perform a reciprocal motion with respect to the sensor <NUM>, in the direction indicated by arrow <NUM>. As the target strip <NUM> travels underneath the sensor <NUM>, the transmitting coil <NUM> may generate a first excitation electromagnetic flux and the transmitting coil <NUM> may generate a second excitation electromagnetic flux. In some implementations, the first transmitting coils <NUM> and <NUM> may be different portions of a single transmitting coil - i.e., they may be run in series as one total transmitting coil. The first excitation electromagnetic flux may induce eddy currents in the conductive features <NUM>, and the induced eddy currents may result in a first reflected electromagnetic flux being emitted from the conductive features <NUM>. The second excitation electromagnetic flux may induce eddy currents in the conductive features <NUM>, and the induced eddy currents may result in a second reflected electromagnetic flux being emitted from the conductive features <NUM>. The receiving coil <NUM> may detect the first reflected electromagnetic flux and generate a signal <NUM>, which is subsequently provided to the processing circuitry <NUM>. The receiving coil <NUM> may detect the first reflected electromagnetic flux and generate a signal <NUM>, which is subsequently provided to the processing circuitry <NUM>. The receiving coil <NUM> may detect the second reflected electromagnetic flux and generate a signal <NUM>, which is subsequently provided to the processing circuitry <NUM>. The receiving coil <NUM> may detect the first reflected electromagnetic flux and generate a signal <NUM>, which is subsequently provided to the processing circuitry <NUM>. The processing circuitry <NUM> may generate an output signal Sout based on the signals <NUM>-<NUM>. The signal Sout may be a digital signal that is indicative of the position of the target strip <NUM> relative to the sensor <NUM>. Further information on the operation of inductive position sensors may be found in <CIT> entitled "Magnetic Field Sensor for Detecting an Absolute Position of a Target Object". Although in the example of <FIG> the sensor <NUM> is an inductive position sensor, it will be understood that the concepts and ideas presented throughout the disclosure are not limited to this type of position sensor, and they can be applied to other types of position sensors, as well.

In another aspect, the receiving coil array <NUM> may have a width that is a multiple of the combined width of the conductive features <NUM> and the voids <NUM>. For example, the width of the receiving coil array <NUM> may be defined by Equation <NUM> below: <MAT> where WIDTH<NUM> is the width of the receiving coil array <NUM>, W1 is the width of any of the conductive features <NUM>, W2 is the width of any of the voids <NUM>, and M<NUM> is a positive integer greater than or equal to <NUM>. According to the present disclosure, it has been determined that configuring the receiving coil array <NUM> to have a width that is a multiple of the combined width of the conductive features <NUM> and the voids <NUM> reduces the error that is present in the signal Sout. In some respects, to minimize stray field impact and inaccuracy (shown in <FIG>), the receiving coil array <NUM> must spread over an integer number of conductive feature <NUM>/void <NUM> pairs.

Additionally or alternatively, the receiving coil array <NUM> may have a width that is a multiple of the combined width of the conductive features <NUM> and voids <NUM>. For example, the width of the receiving coil array <NUM> may be defined by Equation <NUM> below: <MAT> where WIDTH<NUM> is the width of the receiving coil array, W1 is the width of any of the conductive features <NUM>, W2 is the width of any of the voids <NUM>, and M<NUM> is a positive integer greater than or equal to <NUM>. According to the present disclosure, it has been determined that configuring the receiving coil array <NUM> to have a width that is a multiple of the combined with of the conductive features <NUM> and voids <NUM> reduces the error that is present in the signal Sout. In some implementations, the value of M<NUM> may be different from the value of M<NUM>. In some respects, to minimize stray field impact and angle inaccuracy (shown in <FIG>), the receiving coil array <NUM> must spread over an integer number of conductive feature <NUM>/void <NUM> pairs.

In some implementations, each of the arrays <NUM> and <NUM> may be configured to include at least one extra conductive feature on each one of its sides. Under this arrangement, the first and last conductive features in each of the arrays <NUM> and <NUM> may not travel under (or past) the sensor <NUM> when the reciprocal motion is performed to its full extent by the target strip <NUM> in one direction or the other In other words, the number of conductive features in each of arrays <NUM> and <NUM> may be selected, such that when the target strip <NUM> has moved all the way in one direction or the other, there would remain at least one conductive feature in each of arrays <NUM> and <NUM> that is not under and/or has not travelled past the sensor <NUM>. According to the present disclosure, it has been determined that configuring the target strip in this manner helps remove peaks in the error of the signals produced by receiving coil arrays <NUM> and <NUM> which would occur if the last or first conductive feature in one of the arrays <NUM> and <NUM> is under (or has traveled past) a respective one of the receiving coil arrays <NUM> and <NUM>. In the example of <FIG>, the conductive features <NUM>-<NUM> and <NUM>-<NUM> are the first features of arrays <NUM>-<NUM>, and conductive features <NUM>-<NUM> and <NUM>-<NUM> are the last features of arrays <NUM>-<NUM>.

<FIG> shows an example of one possible configuration of the receiving coil array <NUM>. In the example of <FIG>, the receiving coil array <NUM> may have a width A1 and the transmitting coil <NUM> may have a width A2 that is greater than the width A1 by a margin that permits one side of the receiving coil array <NUM> to be spaced by a distance D1 from the transmitting coil <NUM> and the other side of the receiving coil array <NUM> to be spaced by a distance D2 from the transmitting coil <NUM>. According to the present example, the distance D1 is the same as the distance D2, however alternative implementations are possible in which they are different. According to the present disclosure, it has been determined that sizing the receiving coil array <NUM> in a manner that leaves respective buffer spaces between the sides of the receiving coil array <NUM> and the transmitting coil <NUM> results in improved performance of the receiving coil array <NUM>. The nature of the improvement is illustrated in the plots shown in <FIG>.

Shown in <FIG> is a plot 500A of the signals generated by the receiving coils <NUM> and <NUM> (which form the receiving coil array <NUM>) when no buffer space is left between the coil array <NUM> and the transmitting coil <NUM>. An example of a configuration in which no buffer space is provided between the receiving coil array <NUM> and the transmitting coil <NUM> can be seen in <FIG>. Shown in <FIG> is a plot 500B of the signals generated by the coils <NUM> and <NUM> (which form the coil array <NUM>) when buffer spaces are provided between the coil array <NUM> and the transmitting coil <NUM>. An example of a configuration in which buffer space is provided between the receiving coil array <NUM> and the transmitting coil <NUM> is shown in <FIG>. The plots in <FIG> illustrate that providing buffer spaces between the receiving coil array <NUM> and the transmitting coil <NUM> may reduce the offset between the signals generated by coils <NUM> and <NUM>, thus improving the accuracy of the sensor <NUM>. In the absence of buffer spaces, the offset may appear because the vertical traces of the transmitting coil <NUM> (i.e., the traces that are separated by distances D1/D2 in <FIG>) would produce mutual inductance with the receiving coil array <NUM>. Because of its symmetry, the cosine coil (i.e., coil <NUM>) may have no mutual inductance with the sides of the transmitting coil <NUM>, but the sine coil (i.e., coil <NUM>) may have none or negligible mutual inductance, which in turn would result in the signals generated by the two coils being offset in the absence of buffer space.

<FIG> is a diagram illustrating an example of another optimization of the receiving coil array <NUM>. In the example of <FIG>, the width of the receiving coil array <NUM> is increased to cover multiple periods of the target strip <NUM> (by increasing the number of loops in the receiving coils while maintaining the same size and shape of the loops). <FIG> illustrates that increasing the width of the received coil array <NUM> over several conductive features of the target strip <NUM> may help increase the amplitude and reduce the angle error of the signals that are generated by the coils <NUM> and <NUM> (which are part of the receiving coil array <NUM>). The strength of the signals generated by the receiving coils <NUM> and <NUM> increases linearly (e.g., signals <NUM> and <NUM>) with increases in the width of the receiving coils <NUM> and <NUM>.

<FIG> is a diagram illustrating an example of another optimization of the receiving coil array <NUM>. In the example of <FIG>, the coil <NUM> is incudes a first portion having a phase of X degrees and a second portion having a phase of X+<NUM> degrees. Similarly, coil <NUM> includes a first portion having a phase of Y degrees and a second portion having a phase of Y+<NUM> degrees. According to the present disclosure, it has been determined that using phase-shifted loops in any of the receiving coil arrays <NUM> and <NUM> may help increase the amplitude of the signals that are produced by the receiving coil arrays. In some instances, adding phase-shifted loops to the receiving coil arrays <NUM> and <NUM> would result in the output signals of the receiving coil arrays <NUM> and <NUM> being phase-shifted, as well. However, this will have no impact on the coils if the receiving coil arrays <NUM> and <NUM> use the same phase shift. Furthermore, in some instances, the coil <NUM> may include many phase-shifted turns that result in zero phase shift total (e.g., a -<NUM> degree turn and a +<NUM> degree turn). In any event, benefits of using phase shifted coils may include increased signal, reduced harmonic errors, as well as reduced offset errors.

Although in the present example each of the receiving coils in the receiving coil arrays <NUM> and <NUM> includes two phase-shifted loops, alternative implementations are possible in which any of the receiving coils includes any number of receiving coils. The table below illustrates the amount of improvement that can be achieved by adding phase shifted loops to each of receiving coils <NUM> and <NUM>. The first (top) row illustrates the amplitude of signals that are output by receiving coils <NUM> and <NUM> when each of them includes only one loop. The second row illustrates the amplitude of signals that are output by receiving coils <NUM> and <NUM> when each of them includes two coils that are phase-offset from each other by <NUM> degrees. The third row illustrates the amplitude of signals that are output by receiving coils <NUM> and <NUM> when each of them is provided with three phase-shifted loops. In the example of the third row, the phase offset between the first and second loops is <NUM> degrees and the phase offset between the second and third loops (in each of the receiving cols) is also <NUM> degrees. The fourth (bottom) row illustrates the amplitude of signals that are output by receiving coils <NUM> and <NUM> when each of them is provided with three phase-shifted loops. In the example of the fourth row, the phase offset between the first and second loops is <NUM> degrees and the phase offset between the second and third loops (in each of the receiving cols) is <NUM> degrees.

Although the examples of <FIG> and <FIG> are provided with respect to the receiving coil array <NUM> and the transmitting coil <NUM>, it will be understood that the same optimizations may be performed on the receiving coil array <NUM> and the transmitting coil <NUM>, as well.

<FIG> is a diagram of a portion of the system <NUM>, in accordance with another implementation. According to the present disclosure, it has been determined that the presence of the spine <NUM> in the target strip <NUM> may increase the angle error in signals <NUM>-<NUM>. In this regard, <FIG> shows an optimization that can reduce the amount of angle error in the signals <NUM>-<NUM> that is caused by the presence of the spine <NUM> in the target strip <NUM>. In the example of <FIG>, the transmitting coil <NUM> and the coil array <NUM> are spaced from the spine <NUM> by a distance D1, and the transmitting coil <NUM> and the coil array <NUM> are spaced from the spine <NUM> by a distance D2. According to the present example, the distance D1 is the same as the distance D2, however alternative implementations are possible in which the distance D1 is different from the distance D2. According to the present disclosure, it has been determined that, when the width of the coils is <NUM>, setting the distances D1 and D2 to values greater than <NUM> can help reduce angle error in the signals generated by the coils <NUM> and <NUM>.

<FIG> is a diagram of a portion of the system <NUM>, in accordance with another implementation. In the example of <FIG>, the receiving coil arrays <NUM> and <NUM> and the transmitting coils <NUM> and <NUM> are duplicated. In this regard, in the example of <FIG>, the sensor <NUM> further includes a receiving coil array <NUM>', a receiving coil array <NUM>', a transmitting coil <NUM>', and a transmitting coil <NUM>', all of which are formed on the substrate <NUM>.

The receiving coil array <NUM>' may be the same or similar to the receiving coil array <NUM>. The receiving coil array <NUM>' may be formed inside the transmitting coil <NUM>'. The receiving coil array <NUM>' may include coils <NUM>' and <NUM>', as shown. Coil <NUM>' may have a sinusoidal response and coil <NUM>' may have a co-sinusoidal response. In some implementations, the coils <NUM> and <NUM>' may have opposite polarities and the coils <NUM> and <NUM>' may also have opposite polarities. In the example of <FIG>, the signal <NUM> may be generated by subtracting the received signals that are output by the coils <NUM> and <NUM>' and the signal <NUM> may be generated by subtracting the received signals produced by the coils <NUM> and <NUM>'.

The receiving coil array <NUM>' may be the same or similar to the receiving coil array <NUM>. The receiving coil array <NUM>' may be formed inside the transmitting coil <NUM>'. The receiving coil array <NUM>' may include coils <NUM>' and <NUM>', as shown. Coil <NUM>' may have a sinusoidal response and coil <NUM>' may have a co-sinusoidal response. In some implementations, the coils <NUM> and <NUM>' may have opposite polarities and the coils <NUM> and <NUM>' may also have opposite polarities. In the example of <FIG>, the signal <NUM> may be generated by subtracting the received signals that are output by the coils 306and <NUM>' and the signal <NUM> may be generated by subtracting the received signals produced by the coils <NUM> and <NUM>'.

<FIG> is a diagram illustrating an example of the operation of the implementation of the sensor <NUM>, which is shown in <FIG>. In the example of <FIG>, the conductive features <NUM> and <NUM> are sufficiently long to accommodate the additional transmitting/receiving coils. Specifically, the transmitting coils <NUM> and <NUM>' may have a combined length L1 that is smaller than the length of the L2 of the conductive features <NUM>, and the transmitting coils <NUM> and <NUM>' may have a combined length L3 that is smaller than the length L4 of the conductive features <NUM>. As illustrated, the receiving coil arrays <NUM> and <NUM>', as well as the transmitting coils <NUM> and <NUM>', may be positioned over the conductive features <NUM>. Similarly, the receiving coil arrays <NUM> and <NUM>', as well as the transmitting coils <NUM> and <NUM>', may be positioned over the conductive features <NUM>. Duplicating the coils on each side of the spine <NUM> is advantageous because it may increase the magnetic coupling between sensor <NUM> and the target strip <NUM>. This is because most of the coupling between the receiving coil arrays and the target strip <NUM> takes place in proximity to the transmitter coils. Furthermore, imparting opposite polarities on the receiving coils that are disposed on the same side of the spine <NUM> is advantageous because it reduces cross-talk talk between any of the receiving coil arrays that are disposed on one side of the spine <NUM> and the conductive features that are disposed on the other side.

<FIG> is a diagram of the processing circuitry <NUM>, according to one implementation. As illustrated, the processing circuitry may include channels <NUM>-<NUM>, an oscillator <NUM>, a driver <NUM>, an arctan unit <NUM>, an arctan unit <NUM>, a subtraction unit <NUM>, a correction unit <NUM>, and a temperature sensor <NUM>. The driver <NUM> may be configured to drive the transmitting coils <NUM> and <NUM> in response to a signal <NUM> that is provided by the oscillator <NUM>.

The channel <NUM> may include an amplifier <NUM>, a demodulator <NUM>, a gain/offset adjustment unit <NUM>, an analog-to-digital converter (ADC) <NUM>, and a gain/offset adjustment unit <NUM>. The amplifier <NUM> may receive the signal <NUM> from the coil <NUM> and amplify the received signal. The demodulator <NUM> may demodulate the amplified signal based on the signal <NUM>, which is generated by the oscillator <NUM>. The gain/offset adjustment unit <NUM> may perform coarse gain and/or offset adjustment of the demodulated signal to center the demodulated signal into the ADC <NUM>. The ADC <NUM> may digitize the signal output from the gain/offset adjustment unit <NUM>. The gain/offset adjustment unit <NUM> may generate a signal <NUM> by performing temperature compensation and/or any other type of adjustment on the digitized signal that is output by the ADC <NUM>. The gain/offset adjustment unit <NUM> may provide the signal <NUM> to the arctan unit <NUM>.

The channel <NUM> may include an amplifier <NUM>, a demodulator <NUM>, a gain/offset adjustment unit <NUM>, an analog-to-digital converter (ADC) <NUM>, and a gain/offset adjustment unit <NUM>. The amplifier <NUM> may receive the signal <NUM> from the coil <NUM> and amplify the received signal. The demodulator <NUM> may demodulate the amplified signal based on the signal <NUM> which is generated by the oscillator <NUM>. The gain/offset adjustment unit <NUM> may perform coarse gain and/or offset adjustment of the demodulated signal to center the demodulated signal into the ADC <NUM>. The ADC <NUM> may digitize the signal output from the gain/offset adjustment unit <NUM>. The gain/offset adjustment unit <NUM> may generate a signal <NUM> by performing temperature compensation and/or any other type of adjustment on the digitized signal that is output by the ADC <NUM>. The gain/offset adjustment unit <NUM> may provide the signal <NUM> to the arctan unit <NUM>.

The channel <NUM> may include an amplifier <NUM>, a demodulator <NUM>, a gain/offset adjustment unit <NUM>, an analog-to-digital converter (ADC) <NUM>, and a gain/offset adjustment unit <NUM>. The amplifier <NUM> may receive the signal <NUM> from the coil <NUM> and amplify the received signal. The demodulator <NUM> may demodulate the amplified signal based on the signal <NUM> which is generated by the oscillator <NUM>. The gain/offset adjustment unit <NUM> may perform coarse gain and/or offset adjustment of the demodulated signal to center the demodulated signal into the ADC <NUM>. The ADC <NUM> may digitize the signal output from the gain/offset adjustment unit <NUM>. The gain/offset adjustment unit <NUM> may perform temperature compensation and/or any other type of adjustment on the digitized signal, and provide a signal <NUM> to an arctan unit <NUM>.

The arctan unit <NUM> may calculate the arctangent of the quotient of the signals <NUM> and <NUM> to produce a signal S<NUM>. The signals <NUM> and <NUM> have sinusoidal and co-sinusoidal waveforms as a result of the response of coils <NUM> and <NUM>. Accordingly, the signal S<NUM> may indicate _the phase of conductive features 102_. However, the signal S<NUM> alone is not sufficient to identify the absolute position of the target strip <NUM> relative to the sensor <NUM>. A plot of the signal S<NUM> is shown in <FIG>.

The arctan unit <NUM> may calculate the arctangent of the quotient of the signals <NUM> and <NUM> to produce a signal S<NUM>. The signals <NUM> and <NUM> have sinusoidal and co-sinusoidal waveforms as a result of the response of coils <NUM> and <NUM>. Accordingly, the signal S<NUM> may indicate _the phase of conductive features 104_. However, the signal S<NUM> alone is not sufficient to identify the absolute position of the target strip <NUM> relative to the sensor <NUM>. A plot of the signal S<NUM> is shown in <FIG>.

The subtraction unit <NUM> is configured to generate a signal Sd by subtracting the signal S<NUM> from the signal S<NUM>. The signal Sd may indicate the absolute position of the target strip <NUM> relative to the sensor <NUM>. This is made possible because the conductive features <NUM> are staggered with the conductive features <NUM>, which causes each of the conductive features <NUM> to overlap to a different degree with one of the conductive features <NUM>. As noted above, at any given time, the sensor <NUM> measures the reflected electromagnetic fluxes that are generated by a pair of overlapping features <NUM> and <NUM>. Because the overlapping features <NUM> and <NUM> in each pair overlap to a different degree, the difference between magnetic flux through the receiving coil array <NUM> (which is attributable to the conductive feature <NUM>) and the magnetic flux through the receiving coil array <NUM> (which is attributable to the conductive feature <NUM>) can be uniquely attributed to a specific position of the target strip <NUM> relative to the sensor <NUM>. A plot of the signal Sd is shown in <FIG>.

The correction unit <NUM>, is configured to receive the signal Sd and generate the output signal Sout based on the signal Sd. Specifically, the correction unit <NUM> may generate the output signal Sout by executing a process for removing the error that is present in the signal Sd. The process is discussed in further detail with respect to <FIG>.

<FIG> is provided as an example only. It will be understood that the present disclosure is not limited to any specific implementation of the processing circuitry <NUM>. Although in the present example the signal Sout is output from the sensor <NUM>, as is, alternative implementations are possible in which further processing, such as additional trimming and/or linearization, is performed on the signal Sout before it is output. In this regard, the phrases "output signal" or "output signal Sout", as used in the context of <FIG> and <FIG>, shall refer to the signal that is output by the correction unit <NUM> and/or the signal that is generated by executing the process described with respect to <FIG>, irrespective of whether this signal is fed directly to external circuitry or used as a basis for generating another output signal that is itself provided to the external circuitry. The term "unit" as used herein may refer to electronic circuitry configured to perform an action, software configured to perform the action, and/or a combination of software and hardware that are configured to perform the action.

<FIG> show a flowchart of an example of a process <NUM>, according to aspects of the disclosure.

At step <NUM>, the subtraction unit <NUM> receives the signal S<NUM>. At step <NUM>, the subtraction unit <NUM> receives the signal S<NUM>. At step <NUM>, the subtraction unit <NUM> generates the differential signal Sd by subtracting the signal S<NUM> from the signal S<NUM>.

At step <NUM>, the correction unit <NUM> generates an index signal Si<NUM>. The index signal Si<NUM> identifies the index of the conductive feature <NUM> that is in closest proximity to the receiving coil array <NUM> (i.e., closest proximity among all conductive features <NUM> in the target strip <NUM>). For example, if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; and if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'.

In some implementations, the signal Si<NUM> may be generated by rounding (up or down) the ratio of the signal Sd and the period of the array <NUM> of conductive features. In some implementations, the signal Si<NUM> may be calculated based on Equation <NUM> below: <MAT> where N is the number of conductive features in the array <NUM> and (<NUM>/N) is the period of the array <NUM>. The constant '<NUM>' is the maximum value of the signal Sd. As used throughout the disclosure, the phrase "period of an array of conductive features" may refer to any value that is related to the density of the conductive features along the width of a target strip. In the present example, the period of the array <NUM> is represented as the inverse of the density of conductive features <NUM> per unit of signal Sd.

At step <NUM>, the correction unit <NUM> calculates an offset index signal So<NUM>. In some implementations, the signal Si<NUM> may be generated by offsetting and rounding down the ratio of the signal Sd and the period of the array <NUM> of conductive features. In some implementations, the signal So<NUM> may be calculated based on Equations <NUM> and <NUM> below: <MAT> <MAT> where K is an offset constant. According to the present example, K is equal to <NUM>. The value of K may be derived using equation <NUM> above. As can be readily appreciated, the signal So<NUM> is an alternative index signal. The signal So<NUM> would be equal to the signal Si<NUM> in circumstances when a given one of the conductive features <NUM> is distinctly most proximate to the receiving coil array <NUM> (i.e., when the given conductive feature <NUM> is directly under receiving coil array <NUM>). The signal So<NUM> would be greater (by <NUM>) than the signal Si<NUM> when the two different conductive features are at roughly the same distance from the receiving coil array <NUM>, but due to noise and other uncertainties in the processing pipeline, it is unclear which one is the closest. In other words, under many (or ideally all) circumstances, one of the signals So<NUM> and Si<NUM> is always guaranteed to identify correctly the index of the target feature <NUM> that is in closest proximity to the receiving coil array <NUM>.

At step <NUM>, the correction unit <NUM> generates an index signal Si<NUM>. The index signal Si<NUM> identifies the index of the conductive feature <NUM> that is in closest proximity to the receiving coil array <NUM> (i.e., closest proximity among all conductive features <NUM> in the target strip <NUM>). For example, if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'; and if the target feature <NUM>-<NUM> is directly underneath or in closest proximity to the receiving coil array <NUM>, the signal Si<NUM> would have the value of '<NUM>'.

In some implementations, the signal Si<NUM> may be generated by rounding off the ratio of the signal Sd and the period of the array <NUM> of conductive features. In some implementations, the signal Si<NUM> may be calculated based on Equation <NUM> below: <MAT> where N+I is the number of conductive features <NUM> in the array <NUM> and (<NUM>/(N+I)) is the period of the array <NUM>. In the present example, the period of the array <NUM> is represented as the inverse of the density of conductive features <NUM> per unit of signal Sd.

At step <NUM>, the correction unit <NUM> calculates an offset index signal So<NUM>. In some implementations, the signal Si<NUM> may be generated by offsetting and rounding off the ratio of the signal Sd and the period of the array <NUM> of conductive features. In some implementations, the signal So<NUM> may be calculated based on Equations <NUM> and <NUM> below: <MAT> <MAT> where K is an offset constant. According to the present example, K is equal to <NUM>. However, alternative implementations are possible in which K is another positive value that is greater than <NUM> and less than <NUM>. As can be readily appreciated, the signal So<NUM> is an alternative index signal. The signal So<NUM> would be equal to the signal Si<NUM> in circumstances when a given one of the conductive features <NUM> is distinctly most proximate to the receiving coil array <NUM> (i.e., when the given conductive feature <NUM> is directly under receiving coil array <NUM>). The signal So<NUM> would be greater (by <NUM>) than the signal Si<NUM> when the two different conductive features are at roughly the same distance from the receiving coil array <NUM>, but due to noise and other uncertainties in the processing pipeline, it is unclear which one is the closest. In other words, under many (or ideally all) circumstances, one of the signals So<NUM> and Si<NUM> is always guaranteed to identify correctly the index of the target feature <NUM> that is in closest proximity to the receiving coil array <NUM>.

At step <NUM>, the current value of a selector function SEL<NUM> is calculated. The selector function SEL<NUM> is a square wave function. The value of the selector function SEL<NUM> may be either logic-high (i.e., TRUE) or logic-low (i.e., FALSE). The value of the selector function SEL<NUM> at any given time may be based on the value of the remainder that is discarded as a result of evaluating the floor function (or another rounding function) when the values of signals Si<NUM> and So<NUM> are calculated at the given time. In some implementations, the selector function SEL<NUM> may be represented by Equation <NUM> below: <MAT> where rem is the remainder function. Equation <NUM> provides that when the remainder that is discounted by the floor function of Equation <NUM> is less than <NUM>, the selector function SEL<NUM> is set to logic-high. Otherwise, the selector function is set to logic-low. In other words, in circumstances in which Equation <NUM> is likely to underestimate the correct value for the signal Si<NUM> (as gleaned from the sheer size of the remainder that was discarded), the selector function SEL<NUM> would be set to logic-high.

At step <NUM>, the current value of a selector function SEL<NUM> is calculated. The selector function SEL<NUM> is a square wave function. The value of the selector function SEL<NUM> may be either logic-high (i.e., TRUE) or logic-low (i.e., FALSE). The value of the selector function at any given time may be based on the value of the remainder that is discarded as a result of evaluating the floor function (or another rounding function) when the values of signals Si<NUM> and So<NUM> are calculated at the given time. In some implementations, the selector function SEL<NUM> may be represented by Equation <NUM> below: <MAT> where rem is the remainder function. Equation <NUM> provides that when the remainder that is discounted by the floor function of Equation <NUM> is less than <NUM>, the selector function SEL<NUM> is set to logic-high. Otherwise, the selector function is set to logic-low. In other words, in circumstances in which Equation <NUM> is likely to underestimate the correct value for the signal Si<NUM> (as gleaned from the sheer size of the remainder that was discarded), the selector function SEL<NUM> would be set to logic-high.

At step <NUM>, the correction unit <NUM> selects one of the value of the signal Si<NUM> and the value of the signal So<NUM>. Specifically, if the value of the selector function SEL<NUM> is logic-high, the value of the signal Si<NUM> is selected. Otherwise, if the value of the selector function SEL<NUM> is logic-low, the value of the signal So<NUM> is selected. In other words, step <NUM> effectively selects one of the conductive feature indices that are represented by the signals Si<NUM> and So<NUM>.

At step <NUM>, the correction unit <NUM> calculates an unwrapped electrical angle Ua<NUM> based on the selected one of the signals Si<NUM> and So<NUM> (at step <NUM>). If, at step <NUM>, the signal Si<NUM> is selected, the value of the unwrapped electrical angle Ua<NUM> is calculated based on Equation <NUM> below. If, at step <NUM>, the signal So<NUM> is selected, the value of the unwrapped electrical angle Ua<NUM> is calculated based on Equation <NUM> below. <MAT> <MAT>.

According to the present disclosure, an unwrapped signal S<NUM> may be any signal that is generated, at least in part, by multiplying the index value (selected at step <NUM>) by the constant of '<NUM>', and adding the signal S<NUM> modulo <NUM> to the resulting product.

At step <NUM>, the correction unit <NUM> calculates the output signal Sout based on the difference between the values of Ua<NUM> and Ua<NUM>. In some implementations, the signal Sout may be calculated based on Equation <NUM> below: <MAT>.

<FIG> is a plot of the signals Si<NUM> and So<NUM>, and the selector function SEL<NUM>. The Y-axis of the plot is conductive feature index. The X-axis of the plot is position of the target strip <NUM> relative to the sensor <NUM>. <FIG> illustrates that the signals So<NUM> and Si<NUM> have a stepped waveform and the selector function SEL<NUM> has a square waveform. <FIG> shows the relationship between the current position of the target strip <NUM> and the values, which the signals Si<NUM> and So<NUM> would have at the same time.

<FIG> is a plot of the signals Si<NUM> and So<NUM>, and the selector function SEL<NUM>. The Y-axis of the plot is conductive feature index. The X-axis of the plot is position of the target strip <NUM> relative to the sensor <NUM>. <FIG> illustrates that the signals S0<NUM> and Si<NUM> have a step waveform and the selector function SEL<NUM> has a square waveform. <FIG> shows the relationship between the current position of the target strip <NUM> and the values, which the signals Si<NUM> and So<NUM> would have at the same time.

<FIG> is a plot of the signals S<NUM> and S<NUM>, and the signal Sd. The Y-axis of the plot is electrical angle (or signal value). The X-axis of the plot is position of the target strip <NUM> relative to the sensor <NUM>. <FIG> shows the relationship between the current position of the target strip <NUM> and the values, which the signals S<NUM>, S<NUM>, and Sd would have at the same time.

<FIG> is a plot of the error in the signals Sd and Sout, and the signal Sd. The Y-axis of the plot is position error. The X-axis of the plot is position of the target strip <NUM> relative to the sensor <NUM>. <FIG> shows the relationship between the current position of the target strip <NUM>, as it is identified by each of the signals Sd and Sout, and the error that is present in each of the signals Sout and Sd at the same time.

In one aspect, <FIG> illustrates some of the advantages of the sensor <NUM> over some conventional position sensors. Some conventional position sensors would use the signal Sd as their output signal. They may use a signal that is calculated in the same manner as the signal Sd as their output signal (or an angular/linear position that is directly derived from the signal) and may lack the processing step associated with the process <NUM>. <FIG> illustrates that the addition of the processing step (performed by process <NUM>) to the list of operations that are performed by the processing circuitry <NUM> can greatly improve the accuracy of the sensor <NUM>.

<FIG> is a diagram of a system <NUM>, according to aspects of the disclosure. In the example of <FIG>, the target strip <NUM> is formed on a flexible substrate, which is adhered around the circumference of a wheel <NUM>. The substrate <NUM> of the sensor <NUM> is imparted a curved shape (or C-shape) and arranged to face the circumference of the wheel <NUM>. In some respects, <FIG> is provided to illustrate that the concepts and ideas presented throughout the disclosure can be used with the same success to measure angular displacement, as they can be used to measure linear displacement.

<FIG> is a diagram of an example of a system <NUM>, according to aspects of the disclosure. In the example of <FIG>, the target <NUM> is configured as a patch, rather than a strip. Specifically, the target features <NUM> of the array <NUM> are arranged in a circle <NUM> and the target features <NUM> of the array <NUM> are arranged in a circle <NUM>. According to the present example, the circle <NUM> is centered with the circle <NUM>. Although, in the present example, the features <NUM> and <NUM> are arranged in a circle, alternative implementations are possible in which the target features in any of the arrays <NUM> and <NUM> are arranged in any type of loop (e.g., oval, etc.). In the example of <FIG>, the receiving coil array <NUM> is bent in an arch that has the same radius as the circle <NUM>, and the receiving coil array <NUM>, the receiving coil array is bent in an arch that has the same radius as the circle <NUM>. Furthermore, in the example of <FIG>, the transmitting coil <NUM> is shaped like the segment of a ring and the transmitting coil <NUM> is also shaped like the segment of a ring. <FIG> illustrates the receiving coil arrays <NUM> and <NUM> and the transmitting coils <NUM> and <NUM> in closer detail. <FIG> illustrates that the point of inflection of each sinusoidal (or co-sinusoidal) segment of the receiving coils in the arrays <NUM> and <NUM> may coincide with a respective point in one of the circles <NUM> and <NUM>. Although not shown in <FIG>, the features <NUM> and <NUM> may be mounted on a substrate (e.g., a flexible or rig substrate) or integrated into a PCB. Although not shown, the features <NUM> and <NUM> may be coupled with one another via a circular spine. <FIG> is provided as an example only, and the present disclosure is not limited to the specific implementation of the target <NUM>, which is shown in <FIG>. In operation, the implementation of the target <NUM>, which is shown in <FIG>, may be mounted on the side of a wheel, a gear, and/or any other moving element.

The concepts and ideas described herein may be implemented, at least in part, via a computer program product, (e.g., in a non-transitory machine-readable storage medium such as, for example, a non-transitory computer-readable medium), for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). Each such program may be implemented in a high-level procedural or object-oriented programming language to work with the rest of the computer-based system. However, the programs may be implemented in assembly, machine language, or Hardware Description Language. The language may be a compiled or an interpreted language, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or another unit suitable for use in a computing environment. A computer program may be deployed to be executed on one computer or multiple computers at one site or distributed across multiple sites and interconnected by a communication network. A computer program may be stored on a non-transitory machine-readable medium that is readable by a general or special purpose programmable computer for configuring and operating the computer when the non-transitory machine-readable medium is read by the computer to perform the processes described herein. For example, the processes described herein may also be implemented as a non-transitory machine-readable storage medium, configured with a computer program, where upon execution, instructions in the computer program cause the computer to operate in accordance with the processes. A non-transitory machine-readable medium may include but is not limited to a hard drive, compact disc, flash memory, non-volatile memory, or volatile memory. The term unit (e.g., an addition unit, a multiplication unit, etc.), as used throughout the disclosure may refer to hardware (e.g., an electronic circuit) that is configured to perform a function (e.g., addition or multiplication, etc.), software that is executed by at least one processor, and configured to perform the function, or a combination of hardware and software.

As is known, some of the above-described electromagnetic flux sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the electromagnetic flux sensing element, and others of the above-described electromagnetic flux sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the electromagnetic flux sensing element. In particular, planar Hall elements tend to have axes of sensitivity perpendicular to a substrate, while metal based or metallic magnetoresistance elements (e.g., GMR, TMR, AMR) and vertical Hall elements tend to have axes of sensitivity parallel to a substrate.

Claim 1:
A system, comprising:
a processing circuitry (<NUM>) configured to generate a signal Sd that is indicative of a position of a target (<NUM>) that includes a first array (<NUM>) of conductive features (<NUM>) and a second array (<NUM>) of conductive features (<NUM>);
a first receiving coil array (<NUM>) configured to sense a first magnetic field that is associated with the first array of conductive features; and
a second receiving coil array (<NUM>) configured to sense a second magnetic field that is associated with the second array of conductive features,
wherein the processing circuitry (<NUM>) is configured to generate the signal Sd based on a signal S<NUM> and a signal S<NUM>, the signal S<NUM> being generated with the first receiving coil array in response to the first magnetic field, and the signal S<NUM> being generated with the second receiving coil array in response to the second magnetic field; and
the processing circuitry is further configured to:
generate a first index signal based on the signal Sd, wherein the first index signal identifies one of the conductive features in the first array of conductive features that is adjacent to the first receiving coil array, and unwrap the signal S<NUM> based on the first index signal to produce an unwrapped signal Ua<NUM>;
generate a second index signal based on the signal Sd, wherein the second index signal identifies one of the conductive features in the second array of conductive features that is adjacent to the second receiving coil array, and unwrap the signal S<NUM> based on the second index signal to produce an unwrapped signal Ua<NUM>; and
generate an output signal Sout based on the unwrapped signals Ua<NUM> and Ua<NUM>, the output signal Sout being indicative of a position of the target.