Position detection device

Abstract

Position detection device, with: a recording medium which is configured with a first recording track in which a non-repetitive signal formed from binary information is recorded, and with a second recording track on which a signal for specifying a reading range within a range of information of one unit for the non-repetitive signal is recorded, and an information reading device for reading each 1-unit piece of information of the non-repetitive signal from the first recording track by using a detection head in the reading area within a range of 1-unit information for the non-repetitive signal, which is specified according to the signal recorded in the second recording track, wherein in the first recording track each 1-unit piece of information is recorded in an effective area that is longer than the read area within the area of ​​the 1-unit information for the non-repetitive signal, wherein the first recording track is formed with an invalid area which records information that is different from the information recorded in the effective area, and which is located at a boundary between areas in which non-repetitive signals are continuously recorded which are formed from the same binary information.

Description

Background of the invention; Field of the invention

[0001] The invention relates to a position detection device, e.g. for use in a machine tool for metal processing, an industrial machine, a robot or the like. Technical background

[0002] A main unit or housing for various machine tools, industrial robots, or the like includes a position detection device for detecting the shift amount and position of a moving part or area, such as a table, stage, or similar. Recently, several cases have come to light where an absolute-type encoder scale was used as the position detection device in industrial machines, which typically contain a machine tool. Technological background information can be found, for example, in US 2003 / 0187609 A1.

[0003] The absolute-type encoder scale has a design in which the mechanical displacement is read as absolute positional information using binary codes or similar methods, based on non-repetitive codes recorded on the scale. Since the absolute-type encoder scale always provides position confirmation relative to the origin, it is not necessary to detect the origin (a return to the origin) each time the power supply is switched on. Furthermore, the absolute position of the corresponding point can be obtained even if the detection head deviates from the scale, namely by the detection head returning to a predetermined position on the scale.

[0004] In the case of a linear encoder of incremental or raster type, which was often used conventionally, it is necessary to perform a return operation to the origin when activating the device or when a problem occurs. However, the absolute encoder scale is advantageous in that no return operation to the origin is necessary.

[0005] A magnetic encoder of absolute type is known as an absolute-type encoder scale or encoder scale, which generates a code forming an absolute value using a non-repetitive arrangement or pattern (M-code arrangement of an M-sequence or the like) formed by combining polarized and non-polarized areas of a magnetic scale to output absolute data (see, e.g., patent documents 1 and 2, Japanese patent publication JP H09-264760A and Japanese patent publication JP 2007-33245A).

[0006] In an absolute-type magnetic encoder, the absolute value-generating code is read from the magnetic scale or magnetic scale, in which arrangement codes or pattern codes of the absolute value-generating code are recorded using the M-code pattern or M-code arrangement, using magnetic resistance effect elements (MR elements).

[0007] Magnetoresistance effect elements (MR elements) include AMR elements using the anisotropic magnetoresistance effect (AMR) of a ferromagnetic material (e.g., a Ni-Fe layer with a low saturated magnetic field, a Ni-Co layer with a high MR change rate, or the like), magnetoresistance effect elements (GMR elements) using a giant magnetoresistance effect (GMR) of the coupling type using a magnetic layer formed by a multilayer structure, and the like.

[0008] In AMR elements, an electrical resistance is enabled to change due to a comparatively small change in the magnetic field (a few Oe to several tens of Oe).

[0009] Furthermore, GMR elements exhibit a higher rate of change in resistance compared to AMR elements. Consequently, it is possible to obtain a better spacing characteristic and higher output signals compared to AMR elements. Since the resistance change is independent of the relative angle between the magnetic field and the electric current, the effects of a diamagnetic field can be reduced in the magnetic layer utilizing the GMR effect by arranging a signal magnetic field parallel to a detection subject material and the longitudinal direction of a field-sensitive array or pattern.

[0010] In the case of a position detection device in which an incremental track (INC) with S-poles and N-poles, which are arranged alternately next to each other in a regular manner, and an absolute track (ABS) with absolute value-forming codes using the M-code arrangement recorded on it are used in combination, as is the case in Fig. As shown in Figure 4, [1] and [0] of the M-code to be recorded in the ABS track correspond to a distance, step, or 1-pitch of the INC track = 1 wavelength (λ) of a playback signal. In response to code information, "presence of record" and "absence of record" are recorded in a medium for each INC 1 wavelength (λ).

[0011] In this case, the AMR elements can measure the absolute value of a magnetic field. However, they cannot distinguish the polarity.

[0012] This means that in a detection case using AMR elements, the MR elements fundamentally exhibit a characteristic in which a resistance value changes depending on the magnitude of a magnetic field applied to an element in a direction perpendicular to the longitudinal direction of the element strips. As long as the magnetic field is applied, the resistance value is reduced from its value when no magnetic field is applied, regardless of the field's direction. Consequently, this method cannot distinguish between the polarized direction.

[0013] In the case where the AMR elements are used, information components of [1] and [0] or [H] and [L] in the respective bits of the M-code correspond to the components “presence of record” and “absence of record” of the magnetic information.

[0014] However, if "presence of record" and "absence of record" are or are recorded in the medium in association with the information [1] and [0] of the M-code for each INC 1 wavelength, the bit of "presence of record" adjacent to a bit corresponding to "absence of record" is provided with an expanded recording width, with the result that it becomes difficult to record / reproduce a signal correctly corresponding to a pitch or 1-pitch of the INC track = 1 wavelength (INC track = 1 wavelength (λ)) of the playback signal.

[0015] Therefore, in a case where the bit corresponding to "presence of record" is adjacent to a bit corresponding to "absence of record," the recording must be performed in such a way that the information is reproduced as accurately as possible by optimizing the recording conditions. However, such an optimization process is not simple and is also influenced by the order of the code sequence.

[0016] For example, the optimization conditions differ depending on a case where there are bits for "presence of record" on two sides, with "absence of record" in between, from a case where there are continuous bits for "presence of record" and the bit for "absence of record" propagates before the adjacent side.

[0017] In this way, the optimization process must be carried out according to the positions of the codes, resulting in a complicated optimization process.

[0018] Furthermore, in a case where information is read from the recording medium in the manner described above, the magnitude of the magnetic field from the medium is reduced when the distance between the MR element and the medium increases. However, because the optimized recording is not capable of exhibiting a uniform magnetization intensity, a uniform reduction is not achieved relative to a change in distance, resulting in the reproduced waveform being prone to variations. Consequently, the distance range for effective reproduction is narrow and limited.

[0019] On the other hand, to avoid the problems described above, a method was proposed in which a bias magnetic field is applied in a direction perpendicular to the longitudinal direction of the MR elements in such a way that the direction of a magnetic field can be distinguished by moving the diamagnetic field operation point to a mean point of change (hereinafter referred to as operation point bias).

[0020] In this case, it is necessary to imprint a uniform bias field or bias laterally on a group of sensors for use in M-code detection. Since a method using a bias field or bias magnet is prone to defects, requiring a strong magnet or magnetic field, this results in defects of a significant size. Consequently, high costs also arise due to the need to create a large distance from the INC track, which is located on the side of the device.

[0021] In a case where a magnetic device other than the MR element is used, e.g. in the form of a hole element, it is difficult, although the bias or premagnetic field described above is not necessary, to design a system capable of achieving a resolution from 10 nm down to the submicrometer range, which is necessary for machine tools and industrial machinery in a setup that uses a general-use hole element.

[0022] The following description can be applied to magnetic devices in general. At points where the same information components of [1] and [0] or [H] and [L] in the respective bits of the M-codes continue consecutively, recording operations in the same direction, i.e., polarization operations, are performed as many times as the number of contiguous or continuous positions. The result is that the polarized region with the same continuous information is brought into a state equivalent to a setup or structure in which a long magnet is formed or is formed. Therefore, depending on the relationship between the continuous or contiguous length and the spacing of the MR elements, as indicated by the solid line in Fig. 34 is indicated, in the vicinity of the midpoint or center in the longitudinal or long direction of the polarized area or region with the same continuous or connected function, i.e. the long magnet, a magnetic field which is or becomes imposed on the MR element, weaker, causing a decrease or reduction in the signal and sometimes also resulting in a detection error.

[0023] The following description can be applied to magnetic-type devices in general. In general, with magnetic devices, the intensity of the resulting magnetic field is reduced exponentially with increasing recording pitches, because, according to the principles of magnetism, the change value in the element is subject to large fluctuations relative to fluctuations in the spacing. For this reason, the application region is limited. Furthermore, it is difficult to establish a stable signal within the application region.

[0024] With regard to the problems described above, commercially available magnetic absolute scale encoders currently use AMR elements for use in machine tools or industrial machines where a resolution in the 10-nano level without an operating point is required.

[0025] Consequently, the binary information depends on the presence or absence of a magnetic recording.

[0026] On the scale side, drums or plate-shaped elements with a length exceeding 4 meters or varying diameters are required. From a cost perspective, media suitable for practical application include coated media, such as alloy magnetic media or similar materials. All of these media possess anisotropy or isotropy in the longitudinal direction. To date, no vertical media capable of achieving such configurations or precision have been realized in practical applications.

[0027] In the case of industrial devices for use in transport operations or the like, where such high resolution and accuracy as described above are not necessary, a rubber magnet or the like can be used as a medium, even if the same MR elements are used, so that a vertical magnetic medium can be used practically.

[0028] In this system, the contiguous or continuous bits can be alternately polarized, since the bit corresponding to "presence of record" is the same regardless of the polarization or polarized directions. Consequently, the problem of contiguous or continuous bits causing a magnetic pole can be solved.

[0029] In the vicinity of a position where the polarized directions or polarization directions change, the magnetic field weakens to create the same state as that which occurs in "absence of record," thus inverting the resulting signal. However, as in Fig. As shown in Figure 34, more ABS sensors are arranged than would be necessary for the number of bits required to correct deviations between ABS bits and also between INC and ABS. Consequently, by providing such a configuration to prevent deviations in the scale or its reference scale, especially since these can cause a read error, the problem can be avoided.

[0030] In this method, an area or surface for use in the actual detection of the ABS corresponds to an area or section in the range of 50% to 60% or the like of a 1-bit length (derived from a setting and mapping of the detection system and a degree or measure of an additional margin), so that a stable area of ​​a signal can be detected.

[0031] In other words, this means that the detection output or detection output signal of the ABS sensor, which is located in the vicinity of the position where polarized directions or polarization directions are changed, which in Fig. 36 are indicated by a halftone dot hatching, which is not used.

[0032] Since the ABS track portion on the magnetic scale depends on the presence or absence of a magnetic recording of binary information, in this setup the bit for "presence of record" adjacent to a bit corresponding to "absence of record" has an expanded recording width as described above. This makes it difficult to correctly record / reproduce a signal corresponding to a distance or pitch (or 1-pitch) of the INC track = 1 wavelength (λ) of the playback signal. For this reason, for example, the following occur:due to the formation (recording) of a bit for "presence of record" adjacent to the bit corresponding to "absence of record" such that a recording must be carried out in order to reproduce information as accurately as possible by optimizing the recording conditions.

[0033] If the operation point bias is used, a binary signal is obtained by controlling polarized directions or polarization directions. In this case, no unpolarized region is localized, so compared to the presence of an unpolarized region, it is advantageous that a recording state and recording conditions for obtaining a more accurate signal can be created more easily. However, such a setup results in the same polarization direction being present in the continuous or connected units, so the problems described earlier persist.

[0034] One method for solving this problem is to specify a system, also known as a frequency modulation system, such as a bi-phase space system or the like, which serves as a method for digital magnetic recording.

[0035] In this system, even in the case of contiguous or continuous bits with the same value, the previously described problems due to flux reversal do not occur.

[0036] However, in this system, continuous or contiguous bits with the same value double the recording frequency (halving the wavelength).

[0037] Therefore, the magnetic field intensity read by the detection sensor is reduced, and the distance characteristics are degraded. Fluctuations in the magnetic field relative to the distance (spacing) become larger and cause a significant signal change. Furthermore, applying this system on a scale or measuring device results in a relationship where the frequency is doubled. This condition, as it exists, limits the effective detection range to 50% in a single bit. Since the binary state is essentially distinguished by the positive or negative of the signal, another problem arises: the effective detection range becomes 50% or less if fluctuations occur.

[0038] The present invention was conceived with these circumstances in mind. The objective is to create a position detection device capable of maintaining a stable recording state without relying on the "absence of record" function in response to the playback of a binary signal.

[0039] These and other objectives of the present invention and specific advantages achieved by means of the present invention will become clear from the detailed description of a preferred embodiment of the invention given below. Summary of the invention

[0040] The present invention relates to a position detection device comprising: a recording medium comprising a first recording track in which a non-repetitive signal formed of binary information is recorded, and a second recording track on which a signal for specifying a reading section within a range of 1-unit information for the non-repetitive signal is recorded, and an information reading device for reading each 1-unit piece of information of the non-repetitive signal from the first recording track by using a detection head in the reading section within a range of 1-unit information for the non-repetitive signal.which is specified according to the signal recorded in the second recording track, wherein in the first recording track each 1-unit information is recorded in an effective section that is longer than the read area within the area of ​​the 1-unit information for the non-repetitive signal.

[0041] In the position detection device according to the present invention, the first recording track is designed with an invalid section which records information that is different from the information recorded in the effective area, and which is arranged at a border portion between areas in which non-repetitive signals are continuously recorded that are formed from the same binary information.

[0042] The position detection device according to the present invention can be configured such that the invalid area, in which information is recorded differently from the information in the effective area, is shorter than the effective area.

[0043] The position detection device according to the present invention can be configured such that the recording medium is a magnetic recording medium and that the information reading device detects a signal recorded in the first recording track as well as a non-repetitive signal recorded in the second recording track using a magnetic detection head.

[0044] The present invention enables the simple maintenance of a stable recording state without the use of "presence of record" upon playback of a binary signal. Furthermore, the same continuous signals, forming a dual-frequency signal, allow for the acquisition of a characteristic that is advantageous compared to the spacing characteristic of an alternative magnetic field of twice the frequency. Moreover, a stable signal can be obtained within a range of 50% or more of a bit. Within the aforementioned range, it is possible to maintain a virtually constant magnetic field intensity within the spacing region to be used. Brief description of the characters Fig. Figure 1 is a block diagram showing the structure of a position detection device in which the present invention has been applied. Fig. Figure 2 is a schematic top view showing a structural example of a grid track or incremental track (INC) and an absolute track (ABS) of a scale unit or unit of measurement in the position detection device described above. Fig. Figure 3 is a block diagram showing a structural example of a signal processing unit in the position detection device described above. Fig. Figure 4 is a characteristic representation showing a magnetic characteristic of an AMR element installed in a head unit of the position detection device described above. Fig. Figure 5 is a representation showing a magnetic characteristic of a TMR element installed at the head unit of the position detection device described above. Fig. Figure 6 is a drawing showing the result of a magnetic field analysis of a detection output performed under the assumption that the polarized ratio or polarization ratio (effective area : invalid area) is 7 : 3 and that a distance (CL) is 100 µm at the scale unit of the position detection device. Fig. Figure 7 is a drawing showing the result of a magnetic field analysis of a detection output performed under the assumption that the polarized ratio or polarization ratio (effective area : invalid area) is 7 : 3 and that a distance (CL) is 200 µm at the scale unit of the position detection device. Fig. Figure 8 is a drawing showing the result of a magnetic field analysis of a detection output performed under the assumption that the polarized ratio or polarization ratio (effective area : invalid area) is 7 : 3 and that a distance (CL) is 300 µm at the scale unit of the position detection device. Fig. Figure 9 is a drawing showing the result of a magnetic field analysis of a detection output performed under the assumption that the polarized ratio or polarization ratio (effective area : invalid area) is 7 : 3 and that a distance (CL) is 400 µm at the scale unit of the position detection device. Fig. 10(A), Fig. 10(B), Fig. 10(C) and Fig. Figure 10(D) are drawings in which each shows a central area of ​​a continuous signal obtained in the case of a polarized ratio or polarization ratio (effective area : invalid area) of 7 : 3, compared with a frequency INC signal (absolute signal) in the scale unit or unit of measurement of the position detection device described above. Fig. Figure 10(A) shows the resulting signal, with a spacing (CL) set to 100 µm. Fig. Figure 10(B) shows the resulting signal, with a spacing (CL) set to 200 µm. Fig. Figure 10(C) shows the resulting signal, with a spacing (CL) set to 300 µm. Fig. Figure 10(D) shows the resulting signal, with a spacing (CL) set to 400 µm. Fig. Figure 11 is a drawing showing a detection position for a spacing characteristic. Fig. 12(A), Fig. 12(B) are drawings showing the spacing characteristics obtained using the Fig. The 10 procedures described were obtained. Fig. Figure 12(A) shows a state that is obtained with a polarized ratio or polarization ratio (effective range : invalid range) set to 7 : 3. Fig. Figure 12(B) shows a state in a case of using a dual-frequency INC signal. Fig. Figure 13 is a drawing showing seven detection ranges (A to G) obtained or obtained by performing magnetic field analyses, whereby the polarized ratio or polarization ratio (effective range : invalid range) is changed in the scale unit or unit of measurement between 5 : 5 and 10 : 0 to investigate influences on the spacing of the above-mentioned position detection device. Fig. Figure 14 is a drawing showing a magnetic field between two ends of each of the seven detection ranges (A to G), wherein the polarized ratio or polarization ratio (effective range : invalid range) is set to 5 : 5 in the scale unit or scale unit, and wherein the spacings (CL) are set to the values ​​of 100 µm, 200 µm, 300 µm and 400 µm for the position detection device mentioned above. Fig. Figure 15 is a drawing showing an output magnetic field or output magnetic field from a continuous recording unit, which is obtained on the basis of magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit at 5 : 5, at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) in the position detection device described above. Fig. 16(A), Fig. 16(B), Fig. 16(C) and Fig. Figure 16(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 5 : 5. Fig. Figure 16(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 16(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 16(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 16(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 17 is a drawing showing a magnetic field between two ends of each of the seven detection ranges or areas (A to G), with the polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or unit of measurement being 6 : 4 and with the spacings (CL) being 100 µm, 200 µm, 300 µm and 400 µm for the position detection device described above. Fig. Figure 18 is a drawing showing an output magnetic field of a continuous recording unit obtained by magnetic field analysis with a polarized ratio (effective area : invalid area) in the scale unit with the value 6 : 4 at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) at the position detection device described above. Fig. 19(A), Fig. 19(B), Fig. 19(C) and Fig. 19(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 6 : 4. Fig. Figure 19(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 19(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 19(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 19(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 20 is a drawing which represents a magnetic field between two ends of each of the seven detection ranges or areas (A to G), with the polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or unit of measurement having the value 7 : 3 and with the spacings (CL) having the values ​​100 µm, 200 µm, 300 µm and 400 µm for the position detection device described above. Fig. Figure 21 is a drawing showing an output magnetic field of a continuous recording unit obtained by magnetic field analysis with a polarized ratio (effective area : invalid area) in the scale unit with the value 7 : 3 at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) at the position detection device described above. Fig. 22(A), Fig. 22(B), Fig. 22(C) and Fig. 22(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 7 : 3. Fig. Figure 22(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 22(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 22(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 22(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 23 is a drawing showing a magnetic field between two ends of each of the seven detection ranges or areas (A to G), with the polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or unit of measurement having the value 8 : 2 and with the spacings (CL) having the values ​​100 µm, 200 µm, 300 µm and 400 µm for the position detection device described above. Fig. Figure 24 is a drawing showing an output magnetic field of a continuous recording unit obtained by magnetic field analysis with a polarized ratio (effective area : invalid area) in the scale unit with the value 8 : 2 at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) of the position detection device described above. Fig. 25(A), Fig. 25(B), Fig. 25(C) and Fig. 25(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 8 : 2. Fig. Figure 25(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 25(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 25(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 25(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 26 is a drawing showing a magnetic field between two ends of each of the seven detection ranges or areas (A to G), with the polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or unit of measurement having the value 9 : 1 and with the spacings (CL) having the values ​​100 µm, 200 µm, 300 µm and 400 µm for the position detection device described above. Fig. Figure 27 is a drawing showing an output magnetic field of a continuous recording unit obtained by magnetic field analysis with a polarized ratio (effective area : invalid area) in the scale unit with the value 9 : 1 at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) at the position detection device described above. Fig. 28(A), Fig. 28(B), Fig. 28(C) and Fig. 28(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 9 : 1. Fig. Figure 28(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 28(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 28(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 28(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 29 is a drawing showing a magnetic field between two ends of each of the seven detection ranges or areas (A to G), with the polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or unit of measurement having the value 10 : 0 and with the spacings (CL) having the values ​​100 µm, 200 µm, 300 µm and 400 µm for the position detection device described above. Fig. Figure 30 is a drawing showing an output magnetic field of a continuous recording unit obtained by magnetic field analysis with a polarized ratio (effective area : invalid area) in the scale unit with the value 10 : 0 at respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) at the position detection device described above. Fig. 31(A), Fig. 31(B), Fig. 31(C) and Fig. 31(D) are drawings, each of which shows a magnetic field intensity distribution over a recording track and a peripheral area thereof at each of the distances (CL) obtained from magnetic field analyses with a polarized ratio or polarization ratio (effective area : invalid area) in the scale unit or scale unit of 10 : 0. Fig. Figure 31(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 31(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 31(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 31(D) shows the resulting signal with a spacing (CL) of 400 µm. The illustrations are taken using the position detection device described above (a color drawing represents a reference figure). Fig. Figure 32 is a drawing showing magnetic field intensities relative to respective individual polarized ratios or polarization ratios for a case where the spacing (CL) is set to 300 µm in the position detection device described above. Fig. Figure 33 is a top view showing a structural example of an optical scale or optical measuring instrument in which the present invention has been applied. Fig. Figure 34 is a drawing showing continuous or connected recording units of respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained from a magnetic field analysis in which an invalid area is placed in the continuous recording units as any other area with a polarization direction in a direction opposite to the polarization direction of an effective area, with a polarized ratio (effective area : invalid area) in the scale unit of measurement of 7 : 3 for the position detection device described above. Fig. Figure 35 is a drawing showing the result of a magnetic field analysis with respect to a state of a magnetic field detected by a detection head for an absolute arrangement in a case where the spacing (CL) is set to 100 µm. This is shown together with the result of a magnetic field analysis for a magnetic field in a case where the area described above was prepared as a long magnet with the same continuous or continuous recorded information. Fig. Figure 36 is a schematic top view showing a structural example of incremental scanning (INC) and absolute scanning (ABS) in a currently used position detection device. Detailed description of preferred embodiments

[0045] With reference to the figures, the following description discusses certain embodiments of the present invention in detail.

[0046] The present invention is applied to a position detection device 100, which, for example, detects the in Fig. 1. It has the structure shown.

[0047] The position detection device 200 is formed by a scale unit 10, a head unit 20 and a processor unit 30.

[0048] The scale unit 10 is provided with an absolute track 11 (ABS) in which an M-code arrangement or pattern is recorded, indicating the absolute value in a measuring direction, the recording being magnetic. Furthermore, an incremental track 12 (INC) is provided, corresponding to S-poles and N-poles that are positioned alternately and regularly along the measuring direction.

[0049] In this case, the position detection device 100 is according to Fig. 2. The absolute track 11 (ABS) of the scale unit 11 is a first recording track in which non-repetitive signals, formed from binary information, are recorded as an M-code arrangement (absolute arrangement) indicating the absolute value in the measurement direction. The raster track 12 or incremental track 12 (INC) of the scale unit 10 is a second recording track (INC) in or on which a signal is recorded that specifies a read range (T1) within a range (T0) of 1-unit information for the non-repetitive signals. In the first recording track, i.e., the absolute track 11 (ABS), each 1-unit piece of information is recorded in an effective range (T2) that is longer than the read range (T1) within the range (T0) of 1-unit information for the non-repetitive signal.

[0050] The largest magnetization length in the absolute track 11 (ABS) is a bit which corresponds to the area (T0) of information of a 1-unit for the non-repetitive signal which is equal to 1 (λ) of the raster signal or increment signal, corresponding to a pitch or spacing of the raster track 12 (INC) in which or on which S-pole and N-pole are alternately placed regularly parallel to each other.

[0051] Furthermore, the absolute track 11 (ABS) of the scale unit 10 at the position detection device 100 [1] and [0] of the M-code arrangement can be specified by magnetization direction and is formed with an invalid section or area (invalid section T3) which contains information that is different from that shown in the effective section or area (effective section T2). This is located at or in a boundary region between areas in which non-repetitive signals are continuously or coherently recorded, which are formed by the same binary information.

[0052] The invalid section (T3), in which information is recorded that differs from the information in the effective section (T2), is shorter than the effective section (T2). In this case, the ratio between the effective section (T2) and the invalid section (T3) is set to 7:3.

[0053] The absolute track 11 (ABS) with this configuration is produced by magnetic recording, e.g. using an M-code pattern or an M-code arrangement (M-code pattern, absolute pattern), with 16 bits which specify the absolute value of the measurement direction, as described in Fig. 2 is shown as a magnetization pattern and a magnetization arrangement in which magnetization inversions are or are repeated alternately along the measurement directions.

[0054] As in Fig. As shown in Figure 3, the head unit 2 is further equipped with an absolute pattern detection head 21 or absolute arrangement detection head 21, which is formed by a plurality of MR detection elements for use in detecting the absolute pattern or absolute arrangement from the absolute track 11 of the scale unit 10. Furthermore, two raster signal detection heads 22A and 22B or incremental signal detection heads 22A and 22B (incremental signal detection heads) are provided for use in detecting the incremental signal or raster signal from the incremental track 12 or raster track 12 of the scale unit or scale unit 10.

[0055] In this case, the absolute arrangement detection head 21 is designed such that the MR detection elements, the number of which is twice as high as the number of bits of the M-code arrangement (absolute arrangement) which specifies the absolute value in the measurement direction, are arranged with a 1 / 2 interval or a distance of one bit.

[0056] The head 20 described above functions as an information reading device, detecting the raster signal or increment signal (INC) recorded in or on the raster track or increment track 12 of the scale unit or scale unit 10, using the raster signal detection heads 22A and 22B. In a read section or read area within a range or section of information of one unit for the non-repetitive signal, i.e., the M-code signal, and specified on the basis of the detected raster signal or increment signal (INC), the head 20 reads each one unit of information of the M-code signal from the absolute track 11 using the absolute arrangement detection head 21.

[0057] In the position detection device 100, the processor unit 30, whose structural example is shown in the block diagram of the Fig. Figure 3 shows a S / H analog selector 31 (S / G & analog selector), A / D converters 32, 32A and 32B, a reading compensation unit 33, a correction circuit 34, a look-up table 35, an M-code conversion unit 36, an addition unit 37, a serial interface unit 38 and the like.

[0058] The S / H analog selector 31 is connected to the absolute arrangement detection head 21 of the scale unit or scale unit 10, which is formed by a plurality of MR detection elements for detecting the absolute arrangement of the absolute track 11.

[0059] The S / H analog selector 31 measures and holds the respective detection outputs or output signals obtained by the multiple MR detection elements of the absolute array detection head 21. The selector 31 outputs an analog signal corresponding to the 16-bit M-code array.

[0060] An analog signal corresponding to the M-code arrangement of 16 bits, which are selected by the S / H analog selector 31, is converted into a digital signal by means of the A / D converter 32.

[0061] In addition, the two raster signal detection heads 22A and 22B are connected to the A / D converters 32A and 32B for use in detecting raster signals from the raster track 12 of the scale unit 10.

[0062] The INC signals, which are received as detection output signals by the two scanning signal detection heads 22A and 22B, are a sine signal (sin(X² π / λ)) and a cosine signal (cos(X² π / λ)) with one λ cycle. They are converted into digital signals by the A / D converters 32A and 32B and fed to the correction circuit 34.

[0063] In the correction circuit 34, corrections for gain, offset, phase, etc., are applied to the INC detection output signals acquired or received by the two scanning signal detection heads 22A and 22B. Using the readout table or lookup table 35, position information, which is converted to high resolution, is calculated and obtained. The position information calculated in this way is supplied to the read compensation unit 33 and the addition unit 37.

[0064] Based on the position information read out by the read compensation unit 33 using the readout table or look-up table 35, a sensor signal is selected at the position detection device 100, which is contained in the read section (T1) of the M-code arrangement of the digital signals that were converted by means of the A / D converter unit 32.

[0065] The detection signal of the M-code arrangement, which was read out in this way and compensated by means of the read compensation unit 33, is converted from the M-code signal to a binary signal by means of the M-code conversion unit 36. The binary signal is fed to the adder 37.

[0066] The adder 37 outputs information obtained by combining the binary signal, which indicates the absolute value in the measuring direction and is supplied by the M-code conversion unit 36, with the position information, which has been converted to a high resolution and obtained from the INC signal by means of the compensation circuit 34, via the serial interface unit 38, as the position detection output signal of the position detection device 100.

[0067] In this case, MR elements can be used which form the absolute arrangement detection head 20 for use in the detection of the M-code application in the position detection device 100, e.g. AMR elements which utilize the anisotropic magnetoresistive effect (AMR) of a ferromagnetic material, GMR elements which utilize the giant magnetoresistive effect (GMR), which utilizes a rate of change in resistance when using a laminated structure between a ferromagnetic material and a non-magnetic material, TRM elements which utilize the tunnel magnetoresistive effect (TMR), which forms a different electrical resistance value of an element, depending on a relative angle of a magnetization direction of a pair of magnetic layers that are stacked on top of each other with a non-magnetic insulating material in between, and the like.

[0068] With regard to a general-purpose MR sensor for use in a position detection device, in a case where the absolute arrangement detection head 21, which is to be installed in the head unit 20 of the position detection device 100, is formed by AMR elements or by GMR elements, since the AMR elements or the GMR elements, whose magnetic characteristics in Fig. As shown in Figure 4, a change in resistance occurs solely in response to the magnetic field intensity. It is possible to distinguish the direction of a magnetic field by moving a non-magnetic field operation point with an externally applied bias magnetic field. Consequently, the information [1] and [0] of the M-code arrangement can be detected by the absolute track 11 (ABS), in which or on which [1] and [0] of the M-code arrangement are recorded, to be indicated by the magnetization directions, as previously described.

[0069] In a case where the absolute arrangement detection head 21 to be installed in the head unit 20 of the position detection device 100 is formed by TMR elements, it is because the TMR elements, whose TMR magnetic characteristics in Fig. As shown in Figure 5, it is possible to configure the elements in a simple manner to exhibit such a characteristic that they change the direction of the output depending on a positive or negative magnetic field. It is possible to distinguish the direction of a magnetic field without the need to apply an external pre-magnetic or bias magnetic field. Consequently, the information [1] and [0] of the M-code arrangement can then also be detected by the absolute track 11 (ABS).

[0070] In addition, by forming the absolute arrangement detection head 21 using the GMR elements or TMR elements, it becomes possible to increase the resistance change ratio (MR ratio) relative to the external magnetic field and thus also to maintain the linearity of the resistance change ratio (MR ratio) in such a way that a detection process with respect to an external magnetic field can be carried out with high precision.

[0071] In the position detection device 100 described above, in a case where a polarized ratio (effective area : invalid area) of 7 : 3 is recorded in an area with the same information with respect to the respective bits of the absolute track 11 (ABS) of the scale unit 10 and M-codes are set, i.e., recorded in an area with [1] or [0] in a continuous or contiguous manner, assuming that the absolute track 11 (ABS) is recorded by a recording medium with BR = 4000 and Hc = 500, states of magnetic fields (A1, A2, A3 and A4) are detected by the absolute arrangement detection head 21 at respective distances (spacings; CL = 100, 200, 300 and 400) and analyzed with respect to the magnetic field; the results are in the Fig. Figures 6 to 9 are shown together with the results of the magnetic field analyses carried out with respect to the states of the magnetic fields (B1, B2, B3 and B4), in a case in which the area or region described above has recorded the same information continuously or continuously and is formed as a long magnet.

[0072] Fig. Figure 6 shows a magnetic field A1, which is or was detected by the absolute arrangement detection head 21 in one case when the spacing (CL) is set to the value 100 µm, together with a magnetic field B1, which was detected in the case of using a long magnet with the position detection device 100 described above.

[0073] Fig. Figure 7 shows a magnetic field A2, which is or was detected by the absolute arrangement detection head 21 in one case when the spacing (CL) is set to the value 200 µm, together with a magnetic field B2, which was detected in the case of using a long magnet with the position detection device 100 described above.

[0074] Fig. Figure 8 shows a magnetic field A3, which is or was detected by the absolute arrangement detection head 21 in one case when the spacing (CL) is set to the value 300 µm, together with a magnetic field B3, which was detected in the case of using a long magnet with the position detection device 100 described above.

[0075] Fig. Figure 9 shows a magnetic field A4, which is or was detected by the absolute arrangement detection head 21 in one case when the spacing (CL) is set to the value 400 µm, together with a magnetic field B4, which was detected in the case of using a long magnet with the position detection device 100 described above.

[0076] As is clear from the Fig. 6 and Fig. As can be seen from Figure 7, in the position detection device 100 described above, if the spacing (CL) is set to 100 µm or 200 µm, each of the magnetic fields A1 and A2 detected by the absolute arrangement detection head 21 allows for the provision of a desired detection output or detection output signal in the central or middle area in comparison with the magnetic field B1 when using the long magnet.

[0077] Furthermore, in the position detection device described above, 100 states of magnetic fields (A5, A6, A7, and A8) in the central area of ​​each of the regions are recorded with the same continuously or consecutively recorded information. This information is then analyzed by the absolute arrangement detection head 21 at respective distances (spacings; CL = 100 µm, 200 µm, 300 µm, and 400 µm) with respect to the magnetic fields. The results are presented in the Fig. Figures 10(A) to 10(D) are shown together with the results of the magnetic field analyses performed with respect to the magnetic fields (B5, B6, B7 and B8) in connection with dual-frequency grid signals (INC) (absolute value). Fig. Figure 10(A) shows the resulting signal with a spacing (CL) of 100 µm. Fig. Figure 10(B) shows the resulting signal with a spacing (CL) of 200 µm. Fig. Figure 10(C) shows the resulting signal with a spacing (CL) of 300 µm. Fig. Figure 10(D) shows the resulting signal with a spacing (CL) of 400 µm.

[0078] In the position detection device 100 described above, in a case of the respective distances (spacing) of (CL = 100 µm, 200 µm, 300 µm or 300 µm) the minimum magnetic field in the detection area or region of the magnetic field A9 in the middle region of the two end positions of the detection areas according to Fig. 11, i.e., the areas with the same continuous or connected recorded information detected by the previously described absolute arrangement detection head 21, virtually a constant value at the respective spacings (CL = 200 µm, 300 µm and 400 µm) according to Fig. 12(A).

[0079] In contrast, at the two end positions of the detection areas or regions, according to Fig. 11 a magnetic field (B9) of a double frequency incremental signal (INC) (absolute value), which is or was detected by the absolute array detection head 21, to a strongly fluctuating value at the respective spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm), as is the case in Fig. 12(B) is shown.

[0080] This means that, in the area described above with the same continuously or continuously recorded information of the absolute track 11 (ABC), the minimum magnetic field in the central region of the detection area or area of ​​the magnetic field A9 of the area or region with the same continuously or continuously recorded information, which is or was detected by the absolute arrangement detection head 21, creates a characteristic that is better than the spacing characteristic of an alternative magnetic field or alternating magnetic field of twice the frequency. Furthermore, a stable signal can be achieved within a range of 50% or more of a bit. It is also possible in the area described above to obtain a virtually constant magnetic field intensity within the spacing region to be used.

[0081] Furthermore, in the position detection device 100 described above, with the polarized ratio or polarization ratio (effective range : invalid range) between 5 : 5 and 10 : 0, magnetic field analyses are performed with the same continuously or coherently recorded information at the scale unit or scale unit 10, and changes in the minimum magnetic field due to the spacing (CL) are measured in seven detection ranges or areas (A to G) according to Fig. 13 confirmed. Consequently, the results shown below are obtained.

[0082] In other words, with respect to the magnetic field in the middle or central area of ​​the region or area with the same continuously or coherently recorded information, in a case where the polarized ratio (effective area : invalid area) is set to the value 5 : 5, when the minimum magnetic field detected by the absolute arrangement detection head 21 is represented at the two end positions of the two ends of each of the seven detection areas or regions (A to G) for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm), each of the values ​​becomes 0 or a negative value, as shown in Fig. 14 is shown, with the result that the M-code information can be detected incorrectly.

[0083] Furthermore, it shows Fig. 15. A magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to 5 : 5. Furthermore, it shows Fig. 16 a magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 5 : 5.

[0084] At Fig. Figure 16 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 16 and Fig. Figure 16(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 16(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 16(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 16(D) shows a case with a spacing (CL) of 400 µm.

[0085] In contrast, in the position detection device 100 described above, when the polarized ratio (effective range : invalid range) of the area or region with the same continuously or coherently recorded information is set to the value 6 : 4 at the scale unit 10, all values ​​are positive values, each of which represents a virtually constant value at the respective distances (spacing, CL = 200 µm, 300 µm and 400 µm) when the minimum magnetic field energy plotted or applied by the absolute arrangement detection head 21 at the two end positions of the two ends of each of the seven detection ranges or regions (A to G) is positive, for each of the distances (spacing, CL = 100 µm, 200 µm, 300 µm and 400 µm). µm) forms, as is the case in connection with Fig. 17 is shown.

[0086] Furthermore, it shows Fig. 18. A magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 6 : 4. Furthermore, it shows Fig. 16 a magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 6 : 4.

[0087] At Fig. Figure 19 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 19 and Fig. Figure 19(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 19(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 19(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 19(D) shows a case with a spacing (CL) of 400 µm.

[0088] In contrast, in the position detection device 100 described above, when the polarized ratio (effective range : invalid range) of the area or region with the same continuously or coherently recorded information is set to the value 7 : 3 at the scale unit 10, the minimum magnetic field energy plotted or applied by the absolute arrangement detection head 21 at the two end positions of the two ends of each of the seven detection ranges or regions (A to G) for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) is positive, with each value representing a virtually constant value at the respective spacings (CL = 200 µm, 300 µm and 400 µm). µm) forms, as is the case in connection with Fig. 20 is shown.

[0089] Furthermore, it shows Fig. 21 a magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 7 : 3. In addition, shows Fig. 16 a magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 7 : 3.

[0090] At Fig. Figure 22 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 22 and Fig. Figure 22(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 22(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 22(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 22(D) shows a case with a spacing (CL) of 400 µm.

[0091] Furthermore, in the position detection device 100 described above, in a case of setting the polarized ratio (effective range : invalid range) of the area or region with the same continuously or coherently recorded information at the scale unit 10 to the value 8 : 2, when the minimum magnetic field energy plotted or applied by the absolute arrangement detection head 21 at the two end positions of the two ends of each of the seven detection ranges or regions (A to G) for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) is or is positive values, each of which represents a virtually constant value at the respective spacings (CL = 200 µm, 300 µm and 400 µm). forms, as is the case in connection with Fig. 23 is shown.

[0092] Furthermore, it shows Fig. 24 a magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 8 : 2. In addition, it shows Fig. 16 a magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 8 : 2.

[0093] At Fig. Figure 25 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 25 and Fig. Figure 25(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 25(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 25(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 25(D) shows a case with a spacing (CL) of 400 µm.

[0094] Furthermore, in the position detection device 100 described above, in a case of setting the polarized ratio (effective range : invalid range) of the area or region with the same continuously or coherently recorded information at the scale unit 10 to the value 9 : 1, when the minimum magnetic field energy plotted or applied by the absolute arrangement detection head 21 at the two end positions of the two ends of each of the seven detection ranges or regions (A to G) for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) is or is positive values, each of which represents a virtually constant value at the respective spacings (CL = 200 µm, 300 µm and 400 µm). forms, as is the case in connection with Fig. 26 is shown.

[0095] Furthermore, it shows Fig. 27 a magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 9 : 1. In addition, it shows Fig. 16 a magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to the value 9 : 1.

[0096] At Fig. Figure 28 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 28 and Fig. Figure 28(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 28(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 28(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 28(D) shows a case with a spacing (CL) of 400 µm.

[0097] Furthermore, in the position detection device 100 described above, in a case of setting the polarized ratio (effective range : invalid range) of the area or region with the same continuously or coherently recorded information at the scale unit 10 to the value 10 : 0, when the minimum magnetic field energy plotted or applied by the absolute arrangement detection head 21 at the two end positions of the two ends of each of the seven detection ranges or regions (A to G) for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) is or is plotted, the resulting graph in connection with Fig. 29 shown.

[0098] Furthermore, it shows Fig. 30 a magnetic field of the area or region described above with the same continuously or coherently recorded information at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to 10 : 0. In addition, it shows Fig. 16 A magnetic field intensity distribution over the recording track units and the peripheral area thereof at each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm) obtained by magnetic field analysis in a case where the polarized ratio (effective area : invalid area) is set to 10 : 0. Fig. Figure 31 (a colored figure serving as a reference figure) represents a blue-colored area ARb with a magnetic field intensity of 0 Oe, whereas a red-colored area ARr describes an area with a magnetic field intensity of 10 Oe or more. Furthermore, Fig. 31 and Fig. Figure 31(A) shows a case with a spacing (CL) of 100 µm. Fig. Figure 31(B) shows a case with a spacing (CL) of 200 µm. Fig. Figure 31(C) shows a case with a spacing (CL) of 300 µm. Fig. Figure 31(D) shows a case with a spacing (CL) of 400 µm.

[0099] The position detection device 100 described above contains Fig. 32 for a case in which, assuming that the distance or gap between the absolute track 11 and the grid track 12 at the scale unit 10 is set to the value 1 mm, when the spacing (CL) is set to the value 300 µm, the results of the magnetic field analyses performed or performed on the expansion or extension of the magnetic field, i.e. the value of the magnetic field leakage outside the recording tracks in Fig. 32 shown.

[0100] In the position detection device 100 described above, as is clearly evident from the results of the magnetic field analyses performed, the value of the minimum magnetic field at the two ends of the detection range or area is virtually constant at the polarized ratio (effective range : invalid range) of 6 : 4 to 9 : 1, as is clearly evident from the results of the magnetic field analyses performed with the polarized ratio (effective range : invalid range) to a value between 5 : 5 and 10 : 0 in an area or region which is continuously or continuously recorded with the same information in the absolute track 11 of the scale unit 10, by means of the absolute arrangement detection head 21 in the area or region with the same continuously or continuously recorded information at the scale unit 10, regardless of the spacing.CL = 200 µm, 300 µm, and 400 µm). Furthermore, the resulting magnetic field intensities increase as the polarization ratio (effective range : invalid range) increases. Additionally, the magnetic field leakage to the recording traces increases as the polarization ratio (effective range : invalid range) increases, because the resulting state is closer to the long magnet state.

[0101] Since the magnetic field intensity of the absolute track 11 and the track-to-track distance relative to the grid track 12 have a trade-off relationship, it is possible to determine the polarization ratio or polarized ratio (effective area : invalid area) from the point of view of actual use in the desired manner.

[0102] In the magnetic recording system described above, the polarized direction is opposite to that of the effective section in all invalid sections of the continuous or continuous recording unit. However, the present invention is not limited to such a system. This means that it is not necessary for the polarized direction to be set in the opposite direction in all invalid sections.

[0103] For example, the polarized direction or polarization direction may be opposite to that in the effective section for any other invalid section in the continuous recording unit.

[0104] Fig. Figure 34 shows an output magnetic field at the continuous or continuous recording unit for each of the spacings (CL = 100 µm, 200 µm, 300 µm and 400 µm), which is obtained from a magnetic field analysis in which, at the continuous recording unit, an invalid area is set as any other area with a polarized direction opposite to the polarized direction of the effective area, wherein the polarized ratio (effective area : invalid area) at the scale unit 10 at the position detection device 100 is set to the value 7 : 3. Furthermore, it shows Fig. 35 the result of a magnetic field analysis with respect to a state of a magnetic field A1, which is or was detected by the absolute arrangement detection head 21 in the case when the spacing (CL) is set to 100 µm, together with the results of the magnetic field analysis on a magnetic field B1 for a case in which the area described above is prepared or formed as a long magnet in the position detection device 100 described above, with the same continuously or coherently recorded information. Additionally, in Fig. 35 an area which is formed with a halftone hatching or a halftone pumping, the detection region.

[0105] It results from Fig. 35 for the position detection device described above, it is clear that the magnetic field A1, which was detected by means of the absolute arrangement detection head 21, has a better detection output in its central area when the spacing (CL) is set to 100 µm compared with a magnetic field B1 when using the long magnet.

[0106] Furthermore, it becomes possible to achieve the same effect as in a system where all non-detection units are polarized in the opposite direction to that of the detection units. This has already been described above. This means that it becomes possible to obtain a characteristic that is better than that of the distance characteristic of an alternative magnetic field or an alternating magnetic field with twice the frequency. Consequently, it is possible to obtain a stable signal within a range of 50% or more of a bit.

[0107] In the polarization system described above, the explanations regarding the setup state that each invalid region in the continuous or contiguous recording units is polarized in the opposite direction to the polarization direction or polarized direction of the effective region. However, the position of the invalid region to be polarized in the opposite direction is not limited to this setup. This means that every third invalid region can be polarized in the opposite direction or according to any other arrangement that may be used. The position of the invalid region to be polarized in the opposite direction to the direction of the effective region is determined such that a spacing characteristic and a minimum signal exhibit the best characteristics.

[0108] Furthermore, the explanations for the polarizing system described above were given for the case where the polarized ratio (effective range : invalid range) is set to the value 7:3. However, the polarized ratio is not limited to this ratio. This means that any polarized ratio (effective range : invalid range) between 5:5 and 10:0 can be used and will yield the same characteristics.

[0109] In the embodiments of the present invention as explained above, the present invention was used in a position detection system 100 of a magnetic recording system. However, there is no limitation with respect to the embodiment described above, e.g. in connection with Fig. 33. The present invention can be applied to a position detection device of an optical system, which is designed with an optical scale or optical dimension 110 with a first recording track 111 in or on which non-repetitive signals formed of binary information are recorded, and with a second recording track 112 in which a signal for specifying a reading range within the range of information of one unit for the non-repetitive signal is recorded.

Claims

[1] Position detection device, with: a recording medium which is configured with a first recording track in which a non-repetitive signal formed from binary information is recorded, and with a second recording track on which a signal for specifying a reading range within a range of information of one unit for the non-repetitive signal is recorded, and an information reading device for reading each 1-unit piece of information of the non-repetitive signal from the first recording track by using a detection head in the reading area within a range of 1-unit information for the non-repetitive signal, which is specified according to the signal recorded in the second recording track, wherein in the first recording track each 1-unit piece of information is recorded in an effective area that is longer than the read area within the area of ​​the 1-unit information for the non-repetitive signal, wherein the first recording track is formed with an invalid area which records information that is different from the information recorded in the effective area, and which is located at a boundary between areas in which non-repetitive signals are continuously recorded which are formed from the same binary information. [2] Position detection device according to claim 1, wherein the invalid area in which information is recorded differently from the information in the effective area is shorter than the effective area. [3] Position detection device according to one of claims 1 to 2, where the recording medium is a magnetic recording medium and wherein the information reading device detects a signal recorded in the first recording track and a non-repetitive signal recorded in the second recording track using a magnetic detection head.

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