Position detection device

Abstract

The present invention provides a position detection device for improving position detection accuracy. The position detection device includes an absolute track on which a recorded binary sequence is recorded. The recorded binary sequence is generated based on the position detection binary sequence. When N is an integer greater than or equal to 2, no identical sequence exists regardless of which N consecutive items are extracted from the position detection binary sequence. An absolute sensor unit reads the recorded binary sequence from the absolute track. The multiple items included in the recorded binary sequence are composed of two binary values. When the two binary values ​​are assumed to be 1 and 0, the recorded binary sequence is a sequence obtained by replacing one of the two values ​​included in the position detection binary sequence with 10 and replacing the other value in the position detection binary sequence with 01.

Description

[0001] This application is based upon and claims the benefit of priority from Japanese patent application JP2020-070606, filed on April 9, 2020, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0002] The present invention relates to a position detection device. Background Art

[0003] In the above-mentioned technical field, Patent Document 1 discloses a position detection device that detects a position by reading a magnetic signal recorded on a magnetic medium based on a non-repetitive code using a magnetic sensor.

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 01-079619 Summary of the Invention

[0005] However, according to the technology described in the above document, the non-repetitive code may include a portion where multiple "1"s appear repeatedly, corresponding to the length of the detection head, or a portion where "0"s and "1"s appear alternately. Therefore, in the method of associating one item of the non-repetitive code with magnetic recording in one direction, there may be portions where the magnetization reversal interval is long and portions where the magnetization reversal interval is short.

[0006] In this case, the waveform interference of the magnetic signal generated by the absolute track is significant, and therefore, there is a concern that the magnetic signal with the waveform interference may affect the position detection accuracy.

[0007] An exemplary embodiment of the present invention provides a position detection device, comprising:

[0008] an absolute track, wherein a recording binary sequence is recorded in the absolute track, the recording binary sequence is generated based on the position detection binary sequence, and when N is an integer greater than or equal to 2, no identical sequence exists no matter which N consecutive items are extracted from the position detection binary sequence; and

[0009] Absolute sensor unit, reads and records binary sequence from absolute track,

[0010] Wherein, a plurality of items included in the record binary sequence are composed of two binary values, and when it is assumed that the two binary values ​​are 1 and 0, the record binary sequence is a sequence obtained by replacing one of the two values ​​included in the position detection binary sequence with the two values ​​10 and replacing the other value in the position detection binary sequence with the two values ​​01.

[0011] According to the present invention, it is possible to provide a position detection device that can ensure sufficient magnetic position detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1A is a block diagram showing the arrangement of the position detection device of the first embodiment.

[0013] Figure 1B It is a diagram for explaining the effects of the position detecting device of the first embodiment.

[0014] Figure 2 is a block diagram for explaining the arrangement of a position detection device of the second embodiment.

[0015] Figure 3A is a block diagram for explaining the detailed arrangement of the position detection device of the second embodiment.

[0016] Figure 3B is a block diagram showing the detailed arrangement of the position detection device of the second embodiment.

[0017] Figure 3C 1 is a flowchart showing the processing procedure of the position detection device of the second embodiment.

[0018] Figure 4 1 and 2 are views for explaining the arrangement of sensors of the position detection device of the second embodiment.

[0019] Figure 5A is a block diagram showing the detailed arrangement of the position detection device of the third embodiment.

[0020] Figure 5B is a block diagram showing the detailed arrangement of a position detection device of the fourth embodiment.

[0021] Figure 5C 1 is a flowchart showing the processing procedure of the position detection device of the second embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangements of the constituent elements, numerical expressions, and numerical values ​​described in these embodiments do not limit the scope of the present invention.

[0023] [First embodiment]

[0024] Reference Figure 1A and Figure 1B The position detecting device 100 of the first embodiment will be described. Figure 1A As shown, the position detection device 100 includes an absolute rail 101 and a sensor unit 102 .

[0025] The absolute track 101 records a recorded binary sequence 112 generated based on the position detection binary sequence 111 , wherein no matter which N consecutive items (N is an integer greater than or equal to 2) are extracted from the position detection binary sequence 111 , there is no identical sequence. Figure 1A An example of N=4 is shown.

[0026] The sensor unit 102 reads the recorded binary sequence 112 from the absolute track 101 while moving in the left-right direction.

[0027] Each of the plurality of items included in the recording binary sequence 112 is formed of one of two values, and it is assumed that the two values ​​are 1 and 0. In this case, the recording binary sequence 112 is a sequence obtained by replacing one of the two values ​​included in the position detection binary sequence 111 with 10 and the other value in the position detection binary sequence with 01.

[0028] According to the above arrangement, since there is no case where three or more 1s or 0s continue in a recorded binary sequence, it is possible to provide a position detection device that detects a position using a magnetic signal that is less affected by waveform interference.

[0029] Figure 1B Graph 120 is an example of a graph showing a change in magnetic flux according to position in conventional technology. Graph 130 is an example of a graph showing a change in magnetic flux according to position in this embodiment.

[0030] In graph 120, significant waveform interference occurs in portion 123 where magnetization occurs three or more times in a row in the same direction (i.e., consecutive 0s or 1s). Because of this, the difference between maximum value 121 in the smallest portion of the waveform and minimum value 122 in the largest portion is so small that it is difficult to determine the value's origin based solely on the magnetic flux at that location.

[0031] On the other hand, in the present embodiment shown in graph 130, since magnetization occurs in the same direction only twice consecutively in any portion, the maximum value 131 of the minimum portion of the waveform and the minimum value 132 of the maximum portion are separated, making them easy to distinguish. This results in high position detection accuracy.

[0032] [Second embodiment]

[0033] Next, we will refer to Figure 2 The position detecting device 200 of the second embodiment will be described. Figure 2As shown, the position detection device 200 includes a magnetic medium 201 and a detection head 202 as a sensor unit, wherein the magnetic medium 201 includes at least one absolute track 211 and at least one incremental track 212. A non-repetitive code is recorded in the absolute track 211, and a repetitive code is recorded in the incremental track 212.

[0034] Magnetic recording is performed by magnetizing the magnetic material in various regions of magnetic medium 201. When used as a linear encoder, magnetic medium 201 has a long plate shape, while when used as a rotary encoder, it has a cylindrical or disk shape. Magnetization is performed in the positive direction or in the negative direction opposite to the positive direction relative to a specific axis. This axis can be longitudinal or perpendicular to magnetic medium 201.

[0035] The detection head 202 is movable relative to the magnetic medium 201. The detection head 202 is a magnetic encoder that includes an incremental sensor unit 221 and an absolute sensor unit 222, which are magnetic detectors that convert magnetic signals into electrical signals, and a signal processor 223 that converts the electrical signals into position information. The relative positions of the incremental sensor unit 221 and the absolute sensor unit 222 in the detection head 202 do not change.

[0036] The incremental sensor unit 221 reads the leakage magnetic field generated from the incremental rail 212 and outputs a signal. The incremental sensor unit 221 and the incremental rail 212 function as a front-back detector, detecting the front-back position of the detection head 202 in one cycle λ.

[0037] The absolute sensor unit 222 reads the leakage magnetic field generated from the absolute track 211 and outputs a signal. The signal processor 223 converts the signal representing the leakage magnetic field into position data 224 representing the position of the detection head 202 on the magnetic medium 201 and outputs the position data to the external system 250.

[0038] Figure 3A and 3B It is a view for explaining an example of the positional relationship between the sensor and the track in magnetic recording. Figure 3A and Figure 3B There is a difference in the position of the absolute sensor unit 222 .

[0039] Absolute track 211 records a recorded binary sequence 312 generated based on position detection binary sequence 311. In position detection binary sequence 311, no identical sequence exists in any of N consecutive items (N is an integer greater than or equal to 2) extracted. Absolute sensor unit 222 reads at least N items from recorded binary sequence 312 every other item and determines the position of the detected sequence within the entire position detection binary sequence, thereby determining the position of detection head 202 on magnetic medium (encoder 201).

[0040] The position detection binary sequence 311 is a sequence generated by an N-bit (N is an integer greater than or equal to 2) LFSR (Linear Feedback Shift Register). The position detection binary sequence 311 is a sequence in which no repeating pattern exists in any of the N bits extracted. Here, the position detection binary sequence 311 generated by a 4-bit LFSR is shown (for example, 110101100100011). In this case, the feedback polynomial is x 4 +x 3 +1, with a period of 15.

[0041] The sequence table 301 is a table that extracts 4 items from the position detection binary sequence and makes them correspond to the position P. The following example is shown: Figure 3A The absolute track 211 shown has a recorded binary sequence 312 corresponding to a position detection binary sequence 311 of 10 items up to 1101011001. One item in the position detection binary sequence 311 is recorded based on a phase encoding method and using the reverse direction of the magnetic polarity. For example, Figure 3A In the example, when the position detection binary sequence 311 is 1, 10 is recorded in the recording binary sequence 312 so that the polarity is reversed from 1 to 0. When the position detection binary sequence 311 is 0, 01 is recorded in the recording binary sequence 312 so that the polarity is reversed from 0 to 1.

[0042] In incremental track 212, magnetic recording is performed by alternating the positive and negative directions, with a wavelength λ as a period. The incremental signal generated by this incremental recording has the same period λ as the recorded binary sequence 312. The incremental sensor unit 221 can detect the preceding and following positions within a period by reading the incremental signal. In other words, the incremental track 212 and incremental sensor unit 221 detect the position corresponding to one of the preceding and following values ​​in the recorded binary sequence 312, at which the detection head is located.

[0043] The signal processor 223 converts the sequence detected by the absolute sensor unit 222 into position data 224 based on the correspondence between the recorded binary sequence 312 and the position detection binary sequence 311. The position of the detection head is then detected based on the position of the converted sequence in the position detection binary sequence, the incremental track 212, and the detection results of the incremental sensor unit 221.

[0044] In the absolute track 211, magnetic recording is performed based on a bit string of 0s and 1s generated by an N-bit LFSR with a given tap sequence. As for this recording, according to the phase encoding method, recording corresponding to one item of the position detection binary sequence is performed within one incremental cycle. That is, this method is a method (2-bit method) in which two items of the recording sequence of the absolute track 211 correspond to one cycle (wavelength λ) of the incremental track 212. The absolute sensor unit 222 detects at least N items (N is an integer greater than or equal to 2) from the recording binary sequence 312 in a manner of every other item. Figure 3A N = 4) sequence.

[0045] If the signal generated by the recording of a given area read by the incremental track 212 is above a given threshold, a 1 is recorded in that area. Conversely, if the signal is below the threshold, a 0 is recorded in that area. These values ​​form a recorded binary sequence 312.

[0046] exist Figure 3A and Figure 3B In the example shown, regarding absolute recording using the phase encoding method, when the position detection binary sequence 311 is 1, the recorded binary sequence is 10 from left to right, and when the position detection binary sequence 311 is 0, the recorded binary sequence is 01. The two recorded binary sequence items corresponding to one item in the position detection binary sequence can also be reversed. That is, when the position detection binary sequence 311 is 1, the recorded binary sequence is 01 from left to right, and when the position detection binary sequence 311 is 0, the recorded binary sequence is 10. Regarding the sensor chips 302 of the absolute sensor unit 222 that read the absolute signal generated by the absolute recording, a group of sensor chips 302 are arranged at equal intervals for each λ.

[0047] Two sensor elements 321 are arranged at intervals of λ / 4 in one sensor chip 302. If the bit length of the LFSR is N, N or more sensor chips 302 are arranged so that at least N consecutive items in the position detection binary sequence will not be repeated. In other words, 2N or more sensor elements 321 are arranged. Figure 3A and Figure 3BIn the example shown, since the bit length of the LFSR is 4, four sensor chips 302 and eight sensor elements 321 are arranged.

[0048] The absolute sensor unit 222 detects and records the binary sequence 312 from the opposing absolute track 211 while moving in the left-right direction.

[0049] Each of the multiple entries included in recording binary sequence 312 is formed from one of two values. Assuming that the two values ​​are 1 and 0, recording binary sequence 312 is a sequence in which one of the two values ​​included in position detection binary sequence 311 is replaced with 10, while the other value in the position detection binary sequence is replaced with 01 (so-called biphasic). This sequence replacement eliminates the deviation in magnetic flux caused by the same recording signal being repeated multiple times. During reading, the values ​​in the position detection binary sequence are replaced with 1 and 0 in reverse direction (from positive to negative or from negative to positive), not in accordance with the positive / negative direction of the magnetic force.

[0050] Signal processor 223 includes inverter 303, discriminator 304, searcher 305, and position detector 306. Inverter 303 generates inversion sequence 332 by bit-inverting detection sequence 331 detected by absolute sensor unit 222. Discriminator 304 determines whether to search for detection sequence 331 or inversion sequence 332 based on the front and back positions detected by incremental sensor unit 221.

[0051] The searcher 305 searches the position detection binary sequence 311 for the detection sequence 331 or the inversion sequence 332 discriminated by the discriminator 304 .

[0052] The position detector 306 detects the position of the absolute sensor unit 222 based on the position of the detection sequence 331 or the inversion sequence 332 found by the searcher 305 in the position detection binary sequence (for example, P=6 here) and the front and back positions detected by the incremental sensor unit 221.

[0053] Since the positional relationship between the incremental sensor unit 221 and the absolute sensor unit 222 does not change, it is possible to determine the position of all the absolute sensor units 222 within one cycle of the absolute track 211 through the incremental signal. Figure 3A As shown, the absolute sensor unit 222 is located in the front half, it can be inferred that the detection sequence 331 is directly part of the position detection binary sequence 311. Figure 3BSince the absolute sensor unit 222 is located in the second half, it can be inferred that the position detection binary sequence includes a read inversion sequence, wherein all items of the read inversion sequence are bit-reversed. The occurrence sequence P (here, P=8) obtained by searching the occurrence sequence in the position detection binary sequence is the position of the detection sequence.

[0054] Conversely, the absolute sensor unit 222 is configured to read N or more bits of magnetic signals in the first or second half. Based on the position within one cycle of the incremental track 212, the detection sequence and its inverse sequence read by the absolute sensor unit 222 can be inferred as a non-repeating code in which one sequence is recorded. By decoding the inferred code into position information, the relative position of the magnetic medium 201 and the detection head 202 can be determined.

[0055] Figure 3C 33 is a flowchart for explaining the processing procedure executed by the signal processor 223. In step S331, the discriminator 304 discriminates the front-back position of the absolute sensor unit 222 based on the signal from the incremental sensor unit 221.

[0056] When the position is determined to be the front position, the searcher 305 searches the position detection binary sequence for the detection sequence 331 itself in step S333. On the other hand, when the position is determined to be the back position, the inverter 303 inverts the detection sequence in step S335 to generate the inverted sequence 332. Furthermore, in step S337, the searcher 305 searches the position detection binary sequence for the inverted sequence 332.

[0057] Next, in step S339 , the position P derived by the search of the searcher 305 is combined with the front and rear positions detected by the incremental sensor unit 221 to detect the position of the absolute sensor unit 222 .

[0058] The above-mentioned processing is realized by executing software on a processor, which can be realized using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0059] Since the position in one cycle of incremental recording can be known from the incremental signal, the signal processor 223 needs to know the position of the recording sequence in the magnetic medium 201 when reading the recording sequence.

[0060] like Figure 4As shown, since the absolute signal approaches the judgment threshold at the end of a region where the magnetic recording is 1 or 0, stable reading cannot be performed. Therefore, an area 401 available for stable reading is set in the center region (1 / 2 width) outside the end. Sensor elements 321 are arranged at intervals of 1 / 2 width.

[0061] In this case, one of the two sensor elements 321 in a group is always present in the usable area 401. Since the position of the sensor chip 302 in a certain area can be determined with sufficient accuracy using the incremental signal, the sensor element 321 in the group of two sensor elements 321 that is present in the usable area 401 can be determined. Therefore, it is possible to determine whether the absolute record in the area is 1 or 0.

[0062] According to the above arrangement, since at most two portions are magnetized in the same direction continuously at any one portion, the position detection accuracy becomes high.

[0063] It should be noted that the incremental sensor unit and incremental rail are described here as components that detect the front-to-back position of the absolute sensor unit. However, the present invention is not limited to this. Any component that detects the front-to-back position with the same period as the absolute rail can be used. Any component that can detect a periodic signal can be used.

[0064] [Third embodiment]

[0065] Next, refer to Figure 5A and Figure 5B A position detecting device 500 of the third embodiment will be described. Figure 5A and Figure 5B This figure illustrates the layout of position detection device 500 of this embodiment. Position detection device 500 of this embodiment differs from that of the second embodiment in that the absolute track recording density is half that of the second embodiment, and the number of absolute track sensor chips is five, with a spacing of 2λ. Furthermore, the structure and operation of signal processor 523 are different. The remaining structure and operation are the same as those of the second embodiment. Therefore, identical reference numerals denote identical structures and operations, and detailed descriptions thereof will be omitted.

[0066] In the absolute track 511, information corresponding to one bit of the position detection binary sequence 513 is magnetically recorded based on the phase encoding method during two periods of the repetitive code of the incremental track 212. The position detection binary sequence 513 is generated by an LFSR having an even number of taps.

[0067] The absolute sensor unit 522 includes a sensor chip 502 that detects a sequence of (N+1) or more items (here, five items) from a recorded binary sequence in a manner of every other item. In other words, the number of sensor chips 502 is equal to the number of bits of the code generated by the LFSR plus 1.

[0068] Two sensor elements 521 are arranged at an interval of λ / 2 in the sensor chip 502. If the bit length of the LFSR is N (for example, 4 in this case), the number of sensor chips 502 is (N+1) or more (for example, 5 in this case).

[0069] If the binary sequence is recorded in the absolute track 211 as in the second embodiment, each magnet becomes smaller and the magnetic force is weakened. Figure 5A and 5B As shown, the size of each magnet of the absolute track 511 is doubled to record the binary sequence 512. That is, one value of the absolute track 511 is recorded in two periods (2λ) of the incremental track 212. Although the recording density (i.e., resolution) is lower than that of the first embodiment, the accuracy is higher due to the strong magnetic force.

[0070] Due to the characteristics of the detection sequence 331 and the inversion sequence 332 read by the absolute sensor unit 522, only one of them exists at one point in the entire position detection binary sequence 513 generated by the LFSR. Utilizing this characteristic, the signal processor 523 estimates the recorded position detection binary sequence 513 and decodes the estimated code into position information, thereby determining the relative position of the magnetic medium 501 and the absolute sensor unit 522.

[0071] The signal processor 523 includes an inverter 303, a searcher 504, a discriminator 505, and a position detector 506. Unlike the searcher 305 of the second embodiment, the searcher 504 searches for both the detection sequence 331 and the inversion sequence 332 in the position detection binary sequence.

[0072] Searcher 504 notifies discriminator 505 of which position of position detection binary sequence 513 contains detection sequence 331 or inversion sequence 332. Discriminator 505 detects which position of absolute track 511 absolute sensor unit 522 faces, based on which position of position detection binary sequence 513 contains detection sequence 331 or inversion sequence 332. In other words, discriminator 505 calculates a rough position. Position detector 506 combines the output of incremental sensor unit 221 with the position discriminator 505's discriminant position to determine the correct position of absolute sensor unit 522.

[0073] Figure 5C3 is a flowchart for explaining the processing procedure performed by the signal processor 523. In step S531, the inverter 303 inverts the detection sequence 331 to generate the inverted sequence 332. Next, in step S533, the searcher 504 searches the position detection binary sequence 513 for the detection sequence 331 and the inverted sequence 332.

[0074] Next, in step S535, it is determined whether the sequence detected in the position detection binary sequence 513 is the detection sequence 331 or the inverted sequence 332. In step S537, the discriminator 505 determines the approximate position of the absolute sensor unit 522 based on the position at which one of the detection sequence 331 and the inverted sequence 332 in the position detection binary sequence 513 is detected and which one is detected.

[0075] Furthermore, in step S537 , the correct position of the absolute sensor unit 222 is determined based on the signal from the incremental sensor unit 221 .

[0076] The above processing is implemented by executing software through a processor, which can be implemented using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0077] This embodiment utilizes the following characteristic: in a sequence generated by an LFSR having an even number of taps, no matter which partial sequence of (N+1) consecutive items is extracted, the sequence obtained by inverting all items of the partial sequence does not exist within a cycle of the sequence generated by the same LFSR. In other words, the detection sequence 331 and the inverted sequence 332 are never simultaneously included in the position detection binary sequence 513. By determining which sequence is present in the sequence, it is possible to determine whether the leading or trailing item is being read in the recorded binary sequence 312 (i.e., the two magnets) of the two items corresponding to one item in the position detection binary sequence 513.

[0078] As described above, according to this embodiment, the size of the magnet and the sensor can be doubled without changing the resolution.

[0079] It should be noted that in this embodiment, five sensor chips 502 are provided. However, the present invention is not limited thereto, and the number of sensor chips 502 may also be six or seven.

[0080] (The reason why only one of the detection sequence and the reversal sequence exists in one position of the binary sequence)

[0081] Assume that (N+1) sensor chips 502 are located at positions facing a given position to detect a binary sequence {b1, b2, ..., bN, bN+1} (here 11010). Figure 5AAs shown in the example, the detection sequence 331 in the first half of the 2λ region corresponding to one bit of the position detection binary sequence is still {b1, b2, ..., bN, bN+1} (here, 11010). On the other hand, the detection sequence 331 in the second half of the 2λ region is {~b1, ~b2, ..., ~bN, ~bN+1} (here, the symbol ~ indicates inversion, Figure 5B In the example shown, the sequence is 00101). The sequence obtained by extracting only the tap sequence from {b1, b2, ..., bN} is {t1, t2, ..., tm}.

[0082] When the sequence generated by the LFSR cycles with a period of 2 or more, the number of taps is always an even number, so m is an even number. Considering that it is generated by a Fibonacci LFSR, (bN+1) is the result of calculating the exclusive OR of all terms {t1, t2, ..., tm}.

[0083] Therefore, the value of (bN+1) depends on the parity of the number of 1s or 0s in {t1, t2, ..., tm}. Similarly, the next generated term of {~b1, ~b2, ..., ~bN} is the result of calculating the exclusive OR of all terms in {~t1, ~t2, ..., ~tm}. Since the parity of the number of 1s or 0s between {t1, t2, ..., tm} and {~t1, ~t2, ..., ~tm} is the same, the next term in {~b1, ~b2, ..., ~bN} is bN+1.

[0084] Therefore, {~b1, ~b2, ..., ~bN, bN+1} exists in the position detection binary sequence. At this point, since {~b1, ~b2, ..., ~bN} only exists at one point in the entire sequence, {~b1, ~b2, ..., ~bN, ~bN+1} does not exist. Therefore, if {~b1, ~b2, ..., ~bN, bN+1} exists in all sequences generated by the N-bit LFSR, then {~b1, ~b2, ..., ~bN, ~bN+1} does not exist. In other words, only one of the detection sequence and the inversion sequence exists at one point in the position detection binary sequence.

[0085] The searcher 504 searches for the order of occurrence of the detection sequence 331 and the inversion sequence 332 in the position detection binary sequence 513. Figure 5A In the example shown, when located in the first half of the region, the occurrence order P (here, P=1) of the detection sequence 331 {b1, b2, ..., bN, bN+1} (here 11010) is obtained, but the occurrence order of the reverse sequence 332 is not obtained. On the contrary, if Figure 5BIn the example shown, when located in the second half of the region, the order of occurrence P (here, P = 1) of {b1, b2, ..., bN, bN+1} (here, 11010) of the inversion sequence 332 is obtained, but the order of occurrence of the detection sequence is not obtained. Therefore, when the order of occurrence of the detection sequence is obtained, it is known that the sensor faces the (2P-1)th (here, the first) magnet of the absolute track 511. When the order of occurrence of the inversion sequence is obtained, it is known that the sensor faces the (2P)th (here, the second) magnet of the absolute track 511. In this embodiment, if resolution is not a problem, the incremental track 212 and the incremental sensor unit 221 are not required. When the incremental track 212 and the incremental sensor unit 221 are used, the resolution can be doubled.

[0086] In the arrangement according to the third embodiment, since the phase encoding method has a maximum magnetization reversal interval of 2, fine-tuning labor can be reduced. The margin itself is also larger than that of NRZ. Furthermore, since each magnet is large, stability is high. It is preferable to selectively use the arrangement of the second embodiment or the arrangement of the third embodiment depending on the sensitivity of the sensor to be used and the distance between the sensor and the magnetic medium during use.

[0087] [Other embodiments]

[0088] Although the present invention has been particularly shown and described with reference to the embodiments, the present invention is not limited to these embodiments. Those skilled in the art will appreciate that various changes may be made to the construction and details without departing from the spirit and scope of the present invention as defined in the claims. Systems or devices including any combination of the features described in the embodiments are within the scope of the present invention.

[0089] In particular, in the above embodiment, a magnetic position detection device (magnetic scale) that detects a position by magnetic force has been described. This embodiment can also be applied to an optical position detection device (laser scale) that detects a position by a laser beam.

[0090] The present invention is applicable to systems including multiple devices or a single apparatus. The present invention is applicable even if an information processing program for implementing the functions of the embodiments is provided to the system or apparatus directly or from a remote site. Therefore, the present invention also includes a program installed in a computer that implements the functions of the present invention, a medium storing the program, and a WWW (World Wide Web) server that allows users to download the program. In particular, the present invention includes at least a non-transitory computer-readable medium storing a program that causes a computer to execute the processing steps included in the above-described embodiments.

Claims

1. A position detection device, characterized in that: include: an absolute track, wherein a first binary sequence generated based on the second binary sequence is recorded on the absolute track; an absolute sensor unit, the absolute sensor unit reading the first binary sequence from the absolute track; an inverter that generates an inversion sequence by bit-inverting the detection sequence detected by the absolute sensor unit; a searcher that searches the second binary sequence for the detection sequence and the inversion sequence; as well as a position detector that detects a position of the absolute sensor unit based on a position of the detection sequence or the inverted sequence in the second binary sequence found by the searcher, The first binary sequence consists of two values, 1 and 0, and the first binary sequence is a sequence obtained by replacing 0 with 10 and 1 with 01, or replacing 0 with 01 and 1 with 10, among the two values ​​1 and 0 contained in the second binary sequence. In the absolute sensor unit, when the recording period of the first binary sequence is set to λ, at least two sensor elements are arranged at intervals of λ / 2 or less.

2. The position detection device according to claim 1, characterized in that: The absolute sensor unit includes a sensor that detects a sequence of at least N+1 terms from the first binary sequence in a manner of every other term.

3. The position detection device according to claim 1, wherein: A discriminator is further included for discriminating which of the two values ​​of the first binary sequence replaced by one value of the second binary sequence is detected by the absolute sensor unit, based on whether the searcher has detected the detection sequence or the inversion sequence.

4. The position detection device according to claim 1, wherein: The absolute sensor unit detects a sequence of at least N items from the first binary sequence in a manner of detecting every other item, The position detection device further includes: a front-back detector that detects which of the two values ​​of the first binary sequence corresponds to a position faced by the absolute sensor unit; and a position detector that converts the sequence detected by the absolute sensor unit according to a correspondence between the first binary sequence and the second binary sequence, and detects the position of the absolute sensor unit based on a position of the converted sequence in the second binary sequence and detection results of the front and rear detectors.

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