Abstract:
A magnetoresistive sensor system includes a plurality of chip carriers, such that each integrated circuit among the plurality of chip carriers is associated with a respective magnetoresistive sensing components. A plurality of magnetoresistive sensing components can be arranged in an array, wherein each magnetoresistive component among the plurality of magnetoresistive components is associated with a respective integrated circuit among the plurality of chip carriers and wherein the plurality of magnetoresistive sensing components comprises sensing components that are spaced irregular from one another in order to optimize the performance of the array and meet requirements of a particular magnetoresistive sensing application.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
   This patent application is a continuation-in-part of U.S. patent application Ser. No. 10/993,964 filed on Nov. 18, 2004, the disclosure of which is incorporated by reference herein in its entirety, and which issued as U.S. Pat. No. 7,173,414 on Feb. 7, 2007. This patent application is also a continuation-in-part of U.S. patent application Ser. No. 11/088,104, filed on Mar. 23, 2005, the disclosure of which is incorporated by reference in its entirety, and which issued as U.S. Pat. No. 7,112,962 on Sep. 26, 2006. 

   TECHNICAL FIELD 
   Embodiments are generally related to sensor methods and systems. Embodiments are also related to position detection devices. Embodiments are additionally related to magnetic sensors. Embodiments also relate to methods and systems for linear and rotary sensing applications. Embodiments additionally relate to thermal compensation methods and systems. 
   BACKGROUND 
   Magnetoresistive (MR) array technology is utilized in a variety of commercial, consumer and industrial detection applications. In some conventional MR systems an apparatus can be provided for determining the position of a member movable along a path. In such a device, a magnet can be attached to the movable member and an array of magnetic field transducers are located adjacent the path. As the magnet approaches, passes and moves away from a transducer, the transducer provides a varying output signal, which can be represented by a single characteristic curve that is representative of any of the transducers. 
   To determine the position of the movable member, the transducers are electronically scanned and data is selected from a group of transducers having an output that indicates relative proximity to the magnet. A curve-fitting algorithm can then be utilized to determine a best fit of the data to the characteristic curve. By placement of the characteristic curve along a position axis, the position of the magnet and therefore the movable member may be determined. 
   In another conventional MR device, a position determining apparatus can be implemented, which includes a magnet that is attached to a movable member that moves along a predefined path of finite length. An array of magnetic field transducers can be located adjacent to the predefined path. The transducers can provide an output signal as the magnet approaches passes and moves away from each transducer. A correction mechanism can also be provided to correct for residual error caused by the non-linearity of the transducers. 
   Such a correction mechanism preferably approximates the residual error with a predetermined function, and applies correction factors that correspond to the predetermined function to offset the residual error. By correcting for the non-linearity of the transducers, the length of the magnet may be reduced and/or the spacing of the transducers may be reduced. 
   An example of a conventional magnetic sensing approach is disclosed, for example, in U.S. Pat. No. 5,589,769, “Position Detection Apparatus Including a Circuit for Receiving a Plurality of Output Signal Values and Fitting the Output Signal Values to a Curve,” which issued to Donald R. Krahn on Dec. 31, 1996, and is assigned to Honeywell International Inc. Another example of a magnetic sensing approach is disclosed in U.S. Pat. No. 6,097,183, “Position Detection Apparatus with Correction for Non-Linear Sensor Regions,” which issued to Goetz et al. on Aug. 1, 2000 and is also assigned to Honeywell International Inc. U.S. Pat. Nos. 5,589,769 and 6,097,183 are incorporated herein by reference in their entirety. Such MR-based devices generally utilize discrete components on a Printed Circuit Board (PCB) assembly to yield the resulting function. 
   One of the problems with magnetoresistive sensors, particularly anisotropic magnetoresistive (AMR) sensors based on an array configuration, is that such systems typically rely upon the use of an array of magnetoresistive elements configured with equal spacings. In the case of linear arrays, this means that the linear centerline-to-centerline spacings are nominally equal. While appropriate for some configurations, this regular spacing prevents high accuracy sensing. One approach for improving sensing involves introducing additional magnetoresistive elements. This approach, however, only adds to the overall production costs of the sensor device. It is therefore believed that a solution to the problems associated with such prior art sensor devices is the design and configuration of an array based on regular spacing, but on irregular spacing, as discussed in greater detail herein. 
   BRIEF SUMMARY 
   The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
   It is, therefore, one aspect of the present invention to provide for improved sensor methods and systems. 
   It is another aspect of the present invention to provide for an improved position detection device 
   It is a further aspect of the present invention to provide for an improved AMR sensor. 
   It is an additional aspect of the present invention to provide for improved linear and rotary sensing applications. 
   It is yet another aspect of the present invention to provide a magnetoresistive sensor array system wherein magnetoresistive sensing components thereof are spaced from one another in an irregular manner in order to optimize sensor data results thereof. 
   The aforementioned aspects of the invention and other objectives and advantages can now be achieved as described herein. A magnetoresistive sensor system is disclosed, which includes a plurality of chip carriers, such that each integrated circuit among the plurality of chip carriers is associated with a respective magnetoresistive sensing components. A plurality of magnetoresistive sensing components can be arranged in an array, wherein each magnetoresistive component among the plurality of magnetoresistive components is associated with a respective integrated circuit among the plurality of chip carriers and wherein the plurality of magnetoresistive sensing components comprises sensing components that are spaced irregular from one another in order to optimize the performance of the array and meet requirements of a particular magnetoresistive sensing application. 
   This can be configured as a linear array or a rotary array, depending upon design considerations. The array can also be configured on a printed circuit board (PCB). In general, by decreasing the spacing between two elements in a particular region of interest, increased accuracy can be achieved over this region. Varying element spacings can be designed into the array to offer varying performance levels by region. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the principles of the disclosed embodiments. 
       FIG. 1  illustrates a top view of a magnetoresistive array sensor system; 
       FIG. 2  illustrates a graph depicting example curves for an eight element magnetoresistive array sensor with regular spacing; 
       FIG. 3  illustrates a graph depicting normalized and compensated generated as a result of processing a magnetoresistive array algorithm; 
       FIG. 4  illustrates a graph depicting data generated by a magnetoresistive array algorithm, wherein sensor ratios remain constant with respect to temperature; 
       FIG. 5  illustrates a graph depicting data generated by a magnetoresistive array algorithm, wherein such data comprises a straight line fit based on linearization achieved with a Fourier compensation; 
       FIG. 6  illustrates an example linear magnetoresistive array that can be implemented based on a PCB configuration; 
       FIG. 7  illustrates an example rotary magnetoresistive array in the form of a segment that can be implemented based on a PCB configuration; 
       FIG. 8  illustrates an example rotary magnetoresistive array in the form of a semi-circle that can be implemented based on a PCB configuration; 
       FIG. 9  illustrates an example rotary magnetoresistive array in the form of a low resolution circle that can be implemented based on a PCB configuration; 
       FIG. 10  illustrates an example rotary magnetoresistive array in the form of a high resolution circle that can be implemented based on a PCB configuration; 
       FIG. 11  illustrates an eight element magnetoresistive array sensor system with equal element spacing thereof; 
       FIG. 12  illustrates a graph depicting data, which can be generated by the eight element magnetoresistive array sensor system depicted in  FIG. 11 ; 
       FIG. 13  illustrates an eight element magnetoresistive array sensor system with equal element spacing thereof, wherein such spacing differs from the spacing present in the configuration depicted in  FIG. 11 ; 
       FIG. 14  illustrates a graph depicting data, which can be generated by the eight element magnetoresistive array sensor system depicted in  FIG. 13 ; 
       FIG. 15  illustrates an eight element magnetoresistive array sensor system with irregular element spacing thereof, in accordance with a preferred embodiment; 
       FIG. 16  illustrate a graph depicting data, which can be generated by the magnetoresistive array sensor system depicted in  FIG. 15 ; 
       FIG. 17  illustrates a rotary magnetoresistive array sensor system with wider angular spacing in accordance with an alternative embodiment; 
       FIG. 18  illustrates a graph depicting data, which can be generated by the rotary magnetoresistive array sensor system depicted in  FIG. 17 , in accordance with an alternative embodiment; 
       FIG. 19  illustrates a rotary magnetoresistive array sensor system with narrower angular spacing in accordance with an alternative embodiment; and 
       FIG. 20  illustrates a graph depicting data, which can be generated by the rotary magnetoresistive array sensor system depicted in  FIG. 19 , in accordance with an alternative embodiment. 
   

   DETAILED DESCRIPTION 
   The particular values and configurations discussed in these nonlimiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope of the invention. 
     FIG. 1  illustrates a top view of a magnetoresistive sensing system  100 , which is described for general illustrative purposes and to depict the context in which a preferred embodiment can be implemented. System  100  generally includes a group of chip carriers, such as, for example, chip carriers  160 ,  162 , and  164 , which function as a housing or carrier for maintaining respective magnetoresistive bridge circuits  121 ,  123  and  125 . Bridge circuits  121 ,  123 , and  125  can each be preferably implemented as anisotropic magnetoresistive (AMR) Wheatstone bridge circuits, depending upon design considerations. System  100  further includes a biasing magnet  102 . The direction of the bias magnet movement associated with biasing magnet  102  is generally indicated by arrows  104  and  106 . Magnetic field lines  110  and  108  associated with magnet  102  are also depicted in  FIG. 1 . 
   Chip carrier  160  includes a plurality of electrical connections or pins  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124 . Similarly, chip carrier  162  includes a plurality of electrical connections or pins  126 ,  128 ,  130 ,  132 ,  134 ,  136 ,  138 ,  140 . Likewise, chip carrier  164  includes a plurality of electrical connections or pins  142 ,  144 ,  146 ,  148 ,  150 ,  152 ,  154 ,  156 . In general the chip carriers  160 ,  162 ,  164  and respective AMR bridge circuits  121 ,  123 ,  125  can be grouped together to form a magnetoresistive array or system  100 . Note that although only three AMR bridge circuits  121 ,  123 ,  125  are depicted in  FIG. 1 , magnetoresistive array  100  can be configured with more or few AMR bridge circuits and associated chip carrier devices, depending upon design considerations. For example, it is possible to implement magnetoresistive array  100  with eight AMR bridge circuits. 
   The movement of the biasing magnet  102  generates a sinusoidal signal response from each magnetoresistive bridge circuit  121 ,  123 ,  125 . The AMR bridge outputs generated by magnetoresistive bridge circuits  121 ,  123 ,  125  are nearly identical to one another; however, their respective phases are shifted due to centerline-to-centerline spacing thereof. Varying sensing schemes can therefore be implemented to interpolate between the AMR bridge circuits  121 ,  123 ,  125  in order to achieve a high absolute accuracy. 
     FIG. 2  illustrates a graph  200  depicting example curves for an eight element magnetoresistive array sensor with regular spacing. Graph  200  includes a legend  202  which is associated with the data depicted in graph  200 . A y-axis  204  generally plots normalize sensor output data, while an x-axis  206  tracks position data in micrometers. 
     FIG. 3  illustrates a graph  300  depicting normalized and compensated generated as a result of processing a magnetoresistive array algorithm. Graph  300  is associated with a legend  302 , which tracks data depicted graph  300 . A y-axis  304  plots sensor response information in data units, while an x-axis  306  tracks position data in millimeters. 
     FIG. 4  illustrates a graph  400  depicting data generated by a magnetoresistive array algorithm, wherein sensor ratios remain constant with respect to temperature. Graph  400  includes a legend  402 , which is associated with the data plotted in graph  400 . A y-axis  402  tracks sensor ration data while an x-axis tracks position data in millimeters. The sensor ratios depicted in graph  400  thus remains constant over temperature. The sensor ratio is generally provided by the formulation SA/(SA−SB), wherein SA is associated with an “A” sensor and sensor SB is associated with a “B” sensor. 
     FIG. 5  illustrates a graph  500  depicting data generated by a magnetoresistive array algorithm, wherein such data comprises a straight line fit based on linearization achieved with Fourier compensation. A legend  501  is associated with graph  500  and relates to compensated and raw data plotted in graph  500 . A y-axis  502  generally tracks scaled output data, while an x-axis  504  tracks position data in millimeters. 
     FIG. 6  illustrates an example linear magnetoresistive array  600  that can be implemented based on a PCB configuration.  FIG. 7  illustrates an example rotary magnetoresistive array  700  in the form of a segment that can be implemented based on a PCB configuration. Similarly,  FIG. 8  illustrates an example rotary magnetoresistive array  800  in the form of a semi-circle that can be implemented based on a PCB configuration. Likewise,  FIG. 9  illustrates an example rotary magnetoresistive array  900  in the form of a low resolution circle that can be implemented based on a PCB configuration. Finally,  FIG. 10  illustrates an example rotary magnetoresistive array  1000  in the form of a high resolution circle that can be implemented based on a PCB configuration. The magnetoresistive arrays depicted in  FIGS. 6-10  are presented in order to demonstrate that many different magnetoresistive array shapes are possible. 
     FIG. 11  illustrates an eight element magnetoresistive array sensor system  1100  with equal or regular element spacing thereof. Note that in  FIGS. 1 and 11 , identical or similar parts or elements are indicated by identical reference numerals. Thus, the eight element magnetoresistive array sensor system  1100  is essentially a variation to the three element configuration of sensor system  100  depicted in  FIG. 1 . In addition to the inclusion of chip carriers  160 ,  161 , and  164 , the eight element magnetoresistive array sensor system  1100  includes chip carriers  166 ,  168 ,  170 ,  172 , and  174  which are essentially identical to one or more of chip carriers  160 ,  161 ,  165 . Chip carriers  166 ,  168 ,  170 ,  172 , and  174  are respectively associated with AMR bridge circuits  127 ,  129 ,  131 ,  133 , and  135 . Spacing between AMR bridge circuits is indicated respectively in  FIG. 11  by a length represented by the variable x. In one possible implementation, the variable x can be, for example, 12.00 millimeters. 
   It is important to appreciate that all previous magnetoresistive array and sensing configurations utilize an array of elements configured with equal spacing. In the case of linear arrays, this means that the linear centerline-to-centerline distance is nominally equal. In the case of rotary arrays, this means that the centerline-to-centerline arc is nominally equal. 
   Through simulation and analysis, it has been determined that a unique ability exists for optimizing the absolute accuracy in a particular region of an array by decreasing the spacing between the pair of elements in a region of interest. The spacing between the remaining elements within the array can then be increased to preserve the overall length of the array. Example simulated data is therefore described herein, which illustrates the significant performance increase that can be gained utilizing this approach. 
     FIG. 12  illustrates a graph  1200  depicting data, which can be generated by the eight element magnetoresistive array sensor system  1100  depicted in  FIG. 11 . Graph  1200  generally includes a legend  1206  which represents the error plot depicted in graph  1200 . A y-axis  1202  generally tracks error data in LSB (i.e., “least significant bits” or quantization levels), while an x-axis  1204  tracks position data in millimeters. Graph  1200  illustrates position error data in LSB&#39;s at 25 degree Celsius based on data generated from an eight element 84.00 linear magnetoresistive array or system with equal element spacing of 12.00 mm, such as, for example, the eight element magnetoresistive array sensor system  1100  depicted in  FIG. 11 . 
     FIG. 13  illustrates an eight element magnetoresistive array sensor system  1300  with equal element spacing thereof, wherein such spacing differs from the spacing present in the configuration depicted in  FIG. 11 . Magnetoresistive array sensor  1300  is also configured with equal spacing of “y” lengths and a total length of “z”. In one potential implementation, the variable y can represent a length of 9.43 millimeters, while the variable z can represent a total length of 66.00 millimeters. Thus, the magnetoresistive array sensor system  1300  can be implemented as an eight element, 66.00 mm linear array with equal spacing of 9.43 mm. 
     FIG. 14  illustrates a graph  1400  depicting data, which can be generated by the eight element magnetoresistive array sensor system  1300  depicted in  FIG. 13 . Graph  1400  is associated with a legend  1402  associated with the data plotted in graph  1400 . A y-axis  1404  tracks error data in LSB&#39;s, while an x-axis  1406  tracks position data in millimeters. Graph  1400  therefore depicts the absolute position error in LSB&#39;s at 24 degrees Celsius for an eight element, 66.00 mm linear array with equal spacing of 9.43 mm. 
     FIG. 15  illustrates an eight element magnetoresistive array sensor system  1500  with irregular element spacing thereof, in accordance with a preferred embodiment. Note that in  FIGS. 11 ,  13  and  15 , identical or similar parts or components are indicated by identical reference numerals. System  1500  differs from the systems depicted in  FIGS. 11 ,  13  and  15  in that system  1500  illustrates irregular spacing. For example, a length “s” is located between AMR bridge circuit  121  and AMR bridge circuit  123 , while a length “t” is present between AMR bridge circuit  123  and AMR bridge circuit  125 . Similarly, a different length “u” is present between AMR bridge circuit  125  and AMR bridge circuit  127 . Likewise, a different length “v” is located between AMR bridge circuit  127  and AMR bridge circuit  129 , and so forth. 
   The total length from the centerline of AMR bridge circuit  121  to the centerline of AMR bridge circuit  135  is represented by the variable “r”. Thus, in some implementations, the length “s” can be, for example, 12.00 mm, while the length “t” may be 10.00 mm. In such an implementation, the length “u” may be 8.00 mm, while the length or spacing “v” can be 6.00 mm. The length or spacing associated with the length “r” can be, for example, 66.00 mm. Thus, the eight element magnetoresistive array sensor system  1500  can be implemented, for example, as an eight element, 66.00 mm linear array with irregular spacing. 
     FIG. 16  illustrates a graph  1600  depicting data, which can be generated by the magnetoresistive array sensor system  1500  depicted in  FIG. 15 . Graph  1600  is associated with a legend  1602 , which represents the data plotted in graph  1600 . A y-axis  1604  generally tracks error data in LSB&#39;s, while an x-axis  1606  plots position data in millimeters. Graph  1600  generally represents the absolute position error in LSB&#39;s at 25 degrees Celsius base don an 8 element, 66.00 mm, linear magnetoresistive array with irregular spacing, such as that depicted in  FIG. 15 . 
   From the foregoing, it can be postulated that the Absolute Position Accuracy is a function of the amount of quantization levels (least significant bits or LSB&#39;s) per pair of elements and the spacing between those elements. The amount of quantization levels is determined by the electronic design and is fixed. However, the element spacing is a function of the magnetic circuit design and is easily optimized per application. Absolute accuracy is improved if the element spacing are moved closer together, but may be worsened if the element spacings are moved further apart. 
   If a high level of accuracy is desired across the whole length of the array, then a sufficient amount of elements must be utilized. However, if there is one particular region of interest within the array where a very high level of accuracy is desired but the accuracy does not have to be as high for the rest of the array, fewer elements may be utilized in the design. Only the particular area of interest where the high level of accuracy is desired needs to have small element spacing. 
   The previous figures generally rely upon linear magnetoresistive array configurations, which provide examples that explain the novelty of implementing irregular element spacings. This concept also applies to all rotary magnetoresistive array configurations as well, some examples of which are provided in greater detail as follows. 
     FIG. 17  illustrates a rotary magnetoresistive array sensor system  1700  with a wider angular spacing in accordance with an alternative embodiment. System  1700  is generally composed of four magnetoresistive sensing components S 4 , S 1 , S 3  and S 2 . An arrow M represents the angular position or magnetic vector associated with system  1700 . As indicated at block  1702 , system  1700  is indicated at an angular position of 37.5 degrees, while at block  1704 , system  1700  is illustrated at an angular position of 15.5 degrees. Thereafter, at block  1706 , system  1700  is depicted at an angular position of +15.5 degrees. Finally, as indicated at block  1708 , system  1700  is depicted at an angular position of +37.5 degrees. 
   The process depicted in  FIG. 17  indicates that as the bias magnet or magnetic circuit rotates in an angle, the resulting field on the die appears to be a uniform vector rotating about similar to the hand on a clock. The centerline of S 1  goes from −37.5 degrees to −15.5 degrees, then to +15.5 degrees and finally to +37.5 degrees. The angular spacings between magnetoresistive components or AMR elements can be provided as follows: (a) S 1  &amp; S 2 =22.0 degrees; (b) S 2  &amp; S 3 =31.0 degrees; and (c) S 3  &amp; S 4 =22.0 degrees. 
     FIG. 18  illustrates a graph  1800  depicting data, which can be generated by the rotary magnetoresistive array sensor system  1700  depicted in  FIG. 17 , in accordance with an alternative embodiment. Graph  1800  is generally associated with a legend  1802  which provides a key indicative of the data plotted in graph  1800 . A y-axis  1804  generally tracks error data in LSB&#39;s, while an x-axis  1806  tracks angular data in degrees. Graph  1800  generally plots example data generated from a four element, 75.0 degree rotary array with 31.0 angular spacing at zero. Graph  1800  is based on an absolute position error in LSB&#39;s at 25 degrees Celsius. 
     FIG. 19  illustrates a rotary magnetoresistive array sensor system  1900  with narrower angular spacing in accordance with an alternative embodiment. System  1900  is generally composed of four magnetoresistive sensing components S 4 , S 1 , S 3  and S 2 . An arrow M represents the angular position or magnetic vector associated with system  1900 . As indicated at block  1902 , system  1900  is indicated at an angular position of −37.5 degrees, while at block  1904 , system  1900  is illustrated at an angular position of −5.0 degrees. Thereafter, at block  1906 , system  1900  is depicted at an angular position of +5.0 degrees. Finally, as indicated at block  1908 , system  1900  is depicted at an angular position of +37.5 degrees. 
   The process depicted in  FIG. 19  indicates that as the bias magnet or magnetic circuit rotates in an angle, the resulting field on the die appears to be a uniform vector rotating about similar to the hand on a clock. The centerline of S 1  goes from −37.5 degrees to −5.0 degrees, then to +5.0 degrees and finally to +37.5 degrees. The angular spacings between magnetoresistive components or AMR elements can be provided as follows: (a) S 1  &amp; S 2 =32.5 degrees; (b) S 2  &amp; S 3 =10.0 degrees; and (c) S 3  &amp; S 4 =32.5 degrees. 
     FIG. 20  illustrates a graph  2000  depicting data, which can be generated by the rotary magnetoresistive array sensor system  1900  depicted in  FIG. 19 , in accordance with an alternative embodiment. Graph  2000  generally illustrates the absolute position error in LSB&#39;s at 25 degrees Celsius and is based on data generated by a four element 75 degree rotary array with 10 degree angular spacing at zero. A legend  2002  provides a key to the data plotted in graph  2000 , while a y-axis  2004  tracks error data in LSB&#39;s. An x-axis  2006  tracks angular data in degrees. 
   It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.