JP6577635B1 - Position detection device - Google Patents

Abstract

An effective detection length is increased without being affected by a change in an offset component due to geomagnetism or temperature characteristics of a magnetic sensor, and without increasing the number of magnetic sensors. A position detection device 1 detects magnetic field values of a plurality of magnets 10A, 10B, 10C, three or more magnetic sensors MS, and a virtual sensor positioned in the middle from detection values of one skipped magnetic sensor. A virtual sensor magnetic field value generation unit 41 to be generated, a magnet moving mechanism 60 that relatively moves a plurality of magnets until at least one reference magnet is detected, and a magnet that faces the magnetic sensor are identified from detection values of the plurality of magnetic sensors. A position determining unit 43 that outputs a position where the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field value of the virtual sensor becomes zero as the position of the magnet specified by the magnet specifying unit 43, A reference magnet position calculation unit 45 that calculates the position of at least one reference magnet based on the output of the signal generation unit 41 is provided. [Selection] Figure 1

Description

  The present invention relates to a position detection device, and more particularly to a magnetic position detection device.

  As a position detection device, a magnetic position detection device that detects the position of a magnet by detecting the magnitude of a magnetic field of a permanent magnet (hereinafter referred to as “magnet”) is known. For example, Patent Document 1 has a magnetic sensor unit in which a plurality of magnetic sensors are arranged on a straight line, and the magnetic field value is zero from the magnetic field distribution obtained by interpolating the magnetic field value detected by each magnetic sensor with a straight line or a curve. A conventional apparatus for detecting the position of a magnet by obtaining a point is disclosed.

JP-A-8-50004

  However, the method described in Patent Document 1 has a problem that when the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism, the point at which the magnetic field value becomes zero shifts and an error occurs. Similarly, even when the offset component changes due to the temperature characteristics of the magnetic sensor or the like, the point at which the magnetic field value becomes zero is shifted and an error occurs. Further, in order to increase detection accuracy by linear interpolation, the number of magnetic sensors must be increased. Furthermore, the magnet detection range is limited to the distance between two magnetic sensors located at both ends of the magnetic sensor unit, and there is a problem that the effective detection length is short.

  The present invention has been made in view of these circumstances, and even when the offset component of each magnetic sensor changes due to the influence of an external magnetic field such as geomagnetism or the temperature characteristics of the magnetic sensor, the effect of these offset components is affected. The effective detection length can be significantly increased by simply increasing the number of magnets without increasing the number of magnetic sensors or increasing the external dimensions of the magnetic sensor unit. An object of the present invention is to provide a simple position detection device.

  In order to solve the above-mentioned problems, the first technical means of the present invention is arranged along three or more permanent magnets arranged at a predetermined distance and a relative moving direction of the plurality of permanent magnets. , A magnetic sensor unit having M (M is an integer of 3 or more) magnetic sensors arranged in a direction to output the maximum detection value when the permanent magnets are closest to each other, and two skipped magnetic sensors And (M-2) the magnetic field values of the first group of virtual sensors as the magnetic field values of the virtual sensor located in the middle of the two skipped magnetic sensors. A virtual sensor magnetic field value generation unit to be generated, a magnet specifying unit for specifying the permanent magnet facing the magnetic sensor from the detection values of the plurality of magnetic sensors, and a magnetic field value of the virtual sensor are interpolated with a straight line or a curve. The magnetic field value of the obtained magnetic field distribution is zero A position signal generation unit that outputs a position of the permanent magnet specified by the magnet specifying unit, a reference magnet determination unit that determines a reference magnet from the plurality of permanent magnets, and at least one reference magnet Until the reference magnet discriminating unit specifies, a magnet moving mechanism that relatively moves a plurality of the permanent magnets, and a reference magnet position calculation that calculates the position of at least one reference magnet based on the output of the position signal generating unit The distance between the magnets of the plurality of permanent magnets is set shorter than the effective detection length of the magnetic sensor unit.

  According to a second technical means, in the first technical means, the virtual sensor magnetic field value generation unit further calculates a difference value between the detection values of the adjacent magnetic sensors, and calculates the difference value as the two adjacent values. The magnetic field value of the (M−1) second group of virtual sensors is calculated as the magnetic field value of the virtual sensor located in the middle of the magnetic sensor, and the position signal generation unit is configured to output the first group of virtual sensors. And the second group of virtual sensors, the position of the permanent magnet specified by the magnet specifying unit at a position where the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field value of the virtual sensor with a straight line or a curve is zero. It outputs as a position, It is characterized by the above-mentioned.

  According to a third technical means, in the first or second technical means, the position signal generation unit specifies the magnetic sensor that outputs the maximum detected value among the magnetic sensors, and is closest to the magnetic sensor. It is determined whether or not the magnetic field value of the virtual sensor and the magnetic field value of the virtual sensor before and after the virtual sensor cross zero, and the magnetic field values of the two virtual sensors straddling zero are linear or curved The position where the magnetic field value becomes zero is output as the position of the permanent magnet.

  According to a fourth technical means, in any one of the first to third technical means, the reference magnet is the permanent magnet having a magnetization direction different from that of the other permanent magnet in the moving direction. It is what.

  According to a fifth technical means, in any one of the first to third technical means, the reference magnet is the permanent magnet having a magnetization intensity different from that of the other permanent magnets. is there.

  A sixth technical means is any one of the first to third technical means, wherein the reference magnets are the permanent magnets positioned at both ends of the plurality of permanent magnets.

  The seventh technical means is characterized in that, in any one of the first to third technical means, the distances between the magnets of the plurality of adjacent permanent magnets are all different.

  According to an eighth technical means, in any one of the first to third technical means, the plurality of permanent magnets constitute one magnet set, and the plurality of magnet sets are arranged along the moving direction. And the said permanent magnet arrange | positioned at each one end part is comprised as said reference magnet, and the combination of the distance of this permanent magnet of the both sides adjacent to this reference magnet and this reference magnet changes with each said reference magnets. It is characterized by this.

  A ninth technical means is the eighth technical means characterized in that the plurality of permanent magnets other than the reference magnet belonging to each magnet set have different inter-magnet distances.

  According to a tenth technical means, in any one of the first to ninth technical means, the magnetic sensors of the magnetic sensor unit are arranged at an equal pitch.

  According to the present invention, even when the offset component of each magnetic sensor changes due to the influence of an external magnetic field such as geomagnetism or the temperature characteristics of the magnetic sensor, the magnetic sensor is not affected by the offset component. The effective detection length can be increased by increasing only the number of magnets without increasing the outer diameter of the magnetic sensor unit or increasing the outer dimension of the magnetic sensor unit, and the detection accuracy can be improved.

It is a figure which shows one structure of the position detection apparatus which concerns on embodiment of this invention. It is a figure which shows arrangement | positioning with the magnet and magnetic sensor of the position detection apparatus which concern on 1st Embodiment. In the position detection apparatus shown in FIG. 2, it is a figure at the time of changing the relative position of a magnet and a magnetic sensor. It is a figure for demonstrating the characteristic of the detection value (magnetic field value) of the magnetic sensor with respect to the magnet which has a predetermined magnetization direction. It is a figure for demonstrating the characteristic of the difference value of each detection value of two skipped magnetic sensors when the magnet which has a predetermined magnetization direction opposes the magnetic sensor. It is a figure which shows the relationship between the position of a magnetic sensor, and the position of a 1st group virtual sensor. It is a figure which shows the example of the processing flow for calculating | requiring the position of the magnet in the effective detection length of a magnetic sensor unit. It is a figure for demonstrating the linear interpolation for calculating | requiring the position of a magnet. It is a figure for demonstrating the characteristic of the detected value (magnetic field value) of the magnetic sensor with respect to the magnet from which a magnetization direction differs. It is a figure for demonstrating the characteristic of the difference value of each detection value of two skipped magnetic sensors when the magnet from which a magnetization direction differs facing a magnetic sensor. It is a figure for demonstrating the positional relationship which a magnet takes within the effective detection length of a magnetic sensor unit in the position detection apparatus which concerns on the 1st Embodiment of this invention. It is a figure at the time of changing the relative position of a magnet and a magnetic sensor in the position detection apparatus shown to FIG. 11A. It is a figure which shows the case where the number of magnets is made into four in the position detection apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the relationship of arrangement | positioning of a magnet and a magnetic sensor in the position detection apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship of arrangement | positioning of a magnet and a magnetic sensor in the position detection apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the relationship of arrangement | positioning of a magnet and a magnetic sensor in the position detection apparatus which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating how to obtain | require the position of a magnet in the position detection apparatus which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the characteristic of the difference value of each detection value of two adjacent magnetic sensors when a magnet opposes the magnetic sensor. It is a figure which shows the relationship between the position of a magnetic sensor, and the position of the virtual sensor which combined the 1st group and the 2nd group.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to a position detection device of the invention will be described with reference to the drawings. In the following description, the configurations denoted by the same reference numerals in different drawings are the same, and the description thereof may be omitted. In addition, this invention is not limited to the illustration in these embodiment, All the changes within the range of the matter described in the claim and within the equal range are included.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a position detection device according to an embodiment of the present invention. In the first embodiment, an example in which three magnets, that is, a first magnet 10A, a second magnet 10B, and a third magnet 10C having different magnetization directions with respect to the moving direction are used as the plurality of magnets. explain. Here, the first magnet 10A is a magnet serving as a reference magnet, and has a magnetization direction different from that of the second magnet 10B and the third magnet 10C with respect to the moving direction. In the following drawings, the magnet that becomes the reference magnet is hatched. In the present invention, the reference magnet is a magnet that serves as a reference for position detection among a plurality of magnets, and can be specified by the position detection device 1 to detect the position. At least one reference magnet is provided in the position detection device 1, and a plurality of reference magnets may be provided.

  The position detection device 1 includes a first magnet 10A, a second magnet 10B, and a third magnet 10C for detection, and the first magnet 10A, the second magnet 10B, and the third magnet. A magnetic sensor unit 100 including a plurality of magnetic sensors MS for detecting 10C, a multiplexer 20 for switching the plurality of magnetic sensors MS, an A / D converter 30 for converting an analog signal from the magnetic sensor MS into a digital signal, A microcomputer 40 that calculates the positions of the first magnet 10A, the second magnet 10B, and the third magnet 10C based on the detection value of the magnetic sensor MS, and an output that outputs the value calculated by the microcomputer 40 as an analog signal A circuit 50 and a magnet moving mechanism 60 are provided. In this specification, the magnetic sensor MS is collectively described without specifying the magnetic sensor, and the magnetic sensor MS is specified with a number like the magnetic sensor MS2 when specifying the magnetic sensor. The same applies to the virtual sensor described later.

  The microcomputer 40 includes, as functional units, a virtual sensor magnetic field value generation unit 41, a position signal generation unit 42, a magnet identification unit 43, a reference magnet determination unit 44, a reference magnet position calculation unit 45, a multiplexer signal generation unit 46, and a magnet movement A signal generation unit 47 is provided. The functions of these functional units can be realized by executing a CPU, ROM, RAM (not shown) of the microcomputer 40 and a control program stored in advance in the ROM.

  As the magnetic sensor MS, a sensor using a Hall element or a saturable coil can be used. As the one using the saturable coil, for example, the saturable coil is excited to the saturation region of the core, and the saturation point of the core is moved by the action of an external magnetic field, for example, Japanese Patent Laid-Open No. 2003-215221 Can be used.

  FIG. 2 is a diagram illustrating a specific arrangement of the magnet and the magnetic sensor of the position detection device according to the first embodiment. FIG. 3 is a diagram illustrating relative positions of the magnet and the magnetic sensor in the position detection device illustrated in FIG. It is a figure at the time of changing a general position. In FIG. 2, the third magnet 10C is omitted. In the present embodiment, M, for example, 11 magnetic sensors MS are arranged on a straight line on the substrate BS at a pitch P of, for example, 10 mm, and are connected to the multiplexer 20. The first magnet 10A, the second magnet 10B, and the third magnet 10C are fixed to a moving mechanism (not shown) apart from each other by a distance L1 between the magnets L2, and both are fixed distances from the magnetic sensors MS1 to MS11. And move parallel to the substrate BS. The magnetization direction of the first magnet 10A serving as the reference magnet is magnetized to the south and north poles with respect to the moving direction, and the magnetization directions of the second magnet 10B and the third magnet 10C are the first magnet serving as the reference magnet. Opposite to the magnet 10A, the magnet is magnetized in the north and south poles in the moving direction. The directions of magnetization may be opposite to each other. The magnetic sensor MS detects the horizontal magnetic fields of the first magnet 10A, the second magnet 10B, and the third magnet 10C. The output characteristics of the detected values for the magnetic fields of the plurality of magnetic sensors MS are the same.

  In the present embodiment, the effective detection length A of the magnetic sensor unit 100 is a distance of 80 mm from the magnetic sensor MS2 to the magnetic sensor MS10, excluding the magnetic sensors MS1 and MS11 at the left and right ends. In the present embodiment, the magnetic sensors MS are arranged at equal intervals with the pitch P, but the arrangement of the magnetic sensors MS may not be equally spaced. In any case, it is assumed that the position of each of the magnetic sensors MS1 to MS11 is stored in the microcomputer 40 in advance. Further, the number M of the magnetic sensors MS is not limited to 11, but 3 or more are required.

  Further, the inter-magnet distance L1 between the first magnet 10A and the second magnet 10B and the inter-magnet distance L2 between the second magnet 10B and the third magnet 10C are based on the effective detection length A of the magnetic sensor unit 100. Is also set to a short distance, and in this embodiment, for example, each is set to 70 mm. FIG. 2 shows a case where the first magnet 10A faces the magnetic sensor MS2, and FIG. 3 shows a case where the second magnet 10B faces the magnetic sensor MS10. As will be described later, the position detection device 1 has a reference within a range from a position where the first magnet 10A faces the magnetic sensor MS2 to a position where the third magnet 10C faces the magnetic sensor MS10. The position of the first magnet 10A serving as a magnet can be detected. Accordingly, the total effective detection length Ltotal of the position detection device 1 is 220 mm, which is obtained by adding the distance L1 (70 mm) and L2 (70 mm) between the magnets to the effective detection length A (80 mm) of the magnetic sensor unit 100.

First, a method for detecting the position of the first magnet 10A when the first magnet 10A is within the effective detection length A of the magnetic sensor unit 100 will be described.
FIG. 4 is a diagram for explaining the characteristics of a magnetic field value that is a detection value of a magnetic sensor for a magnet having a predetermined magnetization direction. In the characteristic graph shown in FIG. 4, a saturable coil is used for the magnetic sensor MS, and neodymium φ5 × 6 is used for the first magnet 10A. 4 indicates the internal value of the microcomputer 40 indicating the magnitude of the magnetic field, and the horizontal axis indicates the coordinate position along the substrate BS. The position 0 mm shown in FIG. 4 is based on the position of the magnetic sensor MS2 as shown in FIG. For example, the magnetic sensor MS1 is at a position of -10 mm, the magnetic sensor MS2 is at a position of 0 mm, the magnetic sensor MS3 is at a position of 10 mm, the magnetic sensor MS4 is at a position of 20 mm, and the magnetic sensor MS10 is at a position of 80 mm. is there. In FIG. 4, the detection value at a position smaller than −10 mm where the position of the magnet deviates from the effective detection length A of the magnetic sensor unit 100 is also shown, but it is not actually used for position detection.

  In FIG. 4, the magnetic field value which is each detection value of magnetic sensor MS1-MS4 is shown. For example, when the first magnet 10A is at a position of 0 mm, the detection values of the magnetic sensors MS1 to MS4 output magnetic field values when the characteristic curves of the magnetic sensors MS1 to MS4 shown in FIG. 4 are 0 mm. Further, when the first magnet 10A is at a position of 10 mm, the detection values of the magnetic sensors MS1 to MS4 output the magnetic field values when the output characteristic curves of the magnetic sensors MS1 to MS4 shown in FIG. 4 are 10 mm. . Thus, each magnetic sensor MS has the maximum detection value when the center of the first magnet 10A and the center of the magnetic sensor MS are at the same position. That is, when the first magnet 10A and the magnetic sensor MS are closest to each other, the magnetic sensor MS is arranged to output the maximum detection value.

  The multiplexer 20 sequentially switches the magnetic sensors MS <b> 1 to MS <b> 11 according to a command from the multiplexer signal generation unit 46 of the microcomputer 40, converts an analog signal from each magnetic sensor MS into a digital signal by the A / D converter 30 and inputs the digital signal to the microcomputer 40. To do.

  As shown in FIG. 4, with the detection value of the magnetic sensor MS, it is difficult to detect the zero point of the magnetic field value by interpolation with a straight line or a curve and detect the position of the first magnet 10A. Therefore, in the present embodiment, a difference value is obtained every time one detection value of the magnetic sensor MS is skipped inside the microcomputer 40, and the calculated difference value is a virtual position located between the two skipped magnetic sensors MS. The magnetic field value of the sensor is used. Specifically, “detection value of magnetic sensor MS3—detection value of magnetic sensor MS1”, “detection value of magnetic sensor MS4—detection value of magnetic sensor MS2”, “detection value of magnetic sensor MS5—detection of magnetic sensor MS3” Value ”...“ Detected value of magnetic sensor MS11−Detected value of magnetic sensor MS9 ”is obtained, and virtual sensors VL1, VL2, VL3,. The magnetic field value of VL9 is used (see FIG. 6 described later).

  FIG. 5 is a diagram for explaining the characteristic of the difference value between the detection values of two skipped magnetic sensors when a magnet having a predetermined magnetization direction faces the magnetic sensor, and FIG. It is a figure which shows the relationship between the position of a magnetic sensor, and the position of a 1st group virtual sensor. The vertical axis in FIG. 5 indicates the internal value of the microcomputer 40 indicating the magnitude of the magnetic field, and the horizontal axis indicates the coordinate position along the substrate BS.

  For example, in the case of the present embodiment, as the predetermined magnetic sensor MS, a difference value between detection values of the magnetic sensor MS1 and the magnetic sensor MS3 skipped from the magnetic sensor, that is, “detection value of the magnetic sensor MS3−magnetic sensor”. “Detected value of MS1” is calculated and set as the magnetic field value of the virtual sensor VL1 located between the magnetic sensor MS1 and the magnetic sensor MS3. In the present embodiment, the position of the virtual sensor VL1 is equal to the position of the magnetic sensor MS2, and the characteristics shown in FIG. 5 are generated. As can be seen from FIG. 5, when the first magnet 10A is at the position of 0 mm, the magnetic field value of the virtual sensor VL1 becomes zero, and the magnetic field value of the virtual sensor VL1 changes substantially linearly before and after the position of 0 mm. Yes.

Next, the virtual sensor VL2 becomes equal to the position of the magnetic sensor MS3 at the intermediate point between the magnetic sensor MS4 and the magnetic sensor MS2, and the difference value of “the detected value of the magnetic sensor MS4−the detected value of the magnetic sensor MS2” is set as the magnetic field. Value. The characteristic of the virtual sensor VL2 is that the characteristic of the virtual sensor VL1 shown in FIG. 5 is shifted by 10 mm in the plus direction of the substrate BS (to the right side of the paper) so that the magnetic field value becomes zero when the magnet is at a position of 10 mm. Characteristics.
Further, the virtual sensor VL3 is equal to the position of the magnetic sensor MS4, and has a magnetic field value equal to the difference value of “the detected value of the magnetic sensor MS5−the detected value of the magnetic sensor MS3”. The characteristics of the virtual sensor VL3 are obtained by shifting the characteristics of the virtual sensor VL1 shown in FIG. 5 by 20 mm in the plus direction of the substrate BS.

  Thereafter, the difference value between the detection values of the two skipped magnetic sensors MS is sequentially obtained, and the obtained difference value is generated as the magnetic field value of the virtual sensor VL located in the middle of the skipped magnetic sensor MS. Finally, a difference value of “the detection value of the magnetic sensor MS11−the detection value of the magnetic sensor MS9” is obtained and set as the magnetic field value of the virtual sensor VL9 at the same position as the magnetic sensor MS10. The characteristics of the virtual sensor VL9 are characteristics obtained by shifting the characteristics of the virtual sensor VL1 shown in FIG. 5 by 80 mm in the plus direction of the substrate BS.

  In the present embodiment, since the number M of the magnetic sensors MS is 11, nine difference values of one skipped magnetic sensor MS are obtained. Further, since the magnetic sensors MS are arranged at an equal pitch P, the intermediate position between the two skipped magnetic sensors MS is between the two skipped magnetic sensors MS as shown in FIG. It becomes equal to the position of the magnetic sensor MS located. Thus, in this embodiment, nine virtual sensors VL1 to VL9 can be generated, and their positions are equal to the positions of the magnetic sensors MS2 to MS10, respectively. Note that the magnetic sensors MS do not need to be arranged at an equal pitch, and in this case, the position of the virtual sensor VL may be an intermediate position of one skipped magnetic sensor based on the position of each magnetic sensor MS. In the present invention, a plurality of virtual sensors positioned between two skipped magnetic sensors MS are referred to as a first group of virtual sensors.

  The microcomputer 40 interpolates the calculated magnetic field values of the virtual sensors VL <b> 1 to VL <b> 9 with a straight line or a curve, obtains a zero point of the magnetic field value, and detects the position of the first magnet 10 </ b> A. The value of the position of the first magnet 10A obtained by the microcomputer 40 is a digital signal, which is converted into a predetermined analog signal by the output circuit 50 and output. When the position of the first magnet 10A is processed as a digital signal, the output circuit 50 may be omitted.

  As described above, in the present invention, since the position of the magnet is obtained based on the difference between the detection values of the two magnetic sensors MS, even if the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism, It is not affected by the detection position of one magnet 10A. Similarly, even when the offset component changes due to the temperature characteristics of the magnetic sensor MS, the detection position of the first magnet 10A is not affected. Therefore, even if the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism, or even if the offset component changes similarly due to the temperature characteristics of the magnetic sensor MS, etc., highly accurate position detection is possible without being affected by these effects. It is. Further, in order to obtain the position of the magnet based on the difference between the detection values of the two magnetic sensors MS, the magnetic sensor MS is arranged in such a direction as to output the maximum detection value when the magnet is closest.

Next, a processing flow of the position detection device will be described including processing for detecting the position of the first magnet 10A using linear interpolation. FIG. 7 is a diagram illustrating an example of a processing flow for obtaining the position of the magnet within the effective detection length of the magnetic sensor unit.
The detection values from the magnetic sensors MS1 to MS11 are sequentially sent to the A / D converter 30 by switching the multiplexer 20 based on the signal from the multiplexer signal generator 46, converted into a digital value, and then the microcomputer 40. Is taken in. The detection value from the magnetic sensor MS may be taken into the microcomputer 40 in parallel with the processing flow shown in FIG.

  In step S1 of FIG. 7, first, 1 is set in the variable n. In step S2, the virtual sensor magnetic field value generation unit 41 shown in FIG. 1 calculates a difference between detection values of the nth and n + 2th magnetic sensors MS, and in step S3, this difference value is calculated for the nth and n + 2th. The magnetic field value of the virtual sensor VL (n) located in the middle of the magnetic sensor MS is stored in the storage device of the microcomputer 40.

  In step S4, it is determined whether or not the value of n + 2 is equal to the number M of the magnetic sensors MS. If not (NO), the process proceeds to step S5, 1 is added to the variable n, and the processes in and after step S2 are performed. repeat. When the value of n + 2 is equal to the number M of the magnetic sensors MS in step S4 (in the case of YES), the process proceeds to step S6, and the position signal generator 42 applies the magnetic sensor MS that has output the maximum detected value (absolute value). The closest virtual sensor VL is specified.

  Next, it moves to step S7 and the magnet specific | specification part 43 specifies the magnet made into the object of a position detection. As will be described later, this process is a process for identifying a magnet facing the magnetic sensor MS from among a plurality of magnets and identifying a magnet for position detection. In the present embodiment, when the first magnet 10A and the second magnet 10B are within the range of the effective detection length A, it is assumed that the first magnet 10A is specified as a position detection target.

  Since the virtual sensor VL that is closest to the magnetic sensor MS that has output the maximum detection value is specified, it is possible to know the approximate position of the first magnet 10A, and to detect the two adjacent virtual sensors VL. This is a reference for searching whether the magnetic field value does not cross the zero point. Next, the process proceeds to step S8, where it is determined whether or not the magnetic field value of the identified virtual sensor VL and the magnetic field values of the virtual sensors before and after the identified virtual sensor VL cross zero.

  For example, in this embodiment, when the detection value of the magnetic sensor MS5 is the largest, the virtual sensor VL closest to the position of the magnetic sensor MS5 is the virtual sensor VL4, and the positions of the magnetic sensor MS5 and the virtual sensor VL4 are the same. . Then, the polarity of the magnetic field value of the virtual sensor VL4 is compared with the polarity of the magnetic field values of the virtual sensors VL3 and VL5 before and after the virtual sensor VL4. If the polarities of the magnetic field values of the two virtual sensors VL are reversed, the magnetic field value crosses zero between the two virtual sensors, and the first magnet 10A exists between the two virtual sensors. It will be.

  If the magnetic field value of the virtual sensor VL3 is positive, the magnetic field value of the virtual sensor VL4 is negative, and the magnetic field value of the virtual sensor VL5 is negative, the magnetic field values of the virtual sensor VL3 and VL4 are opposite in polarity. Therefore, it turns out that there exists the 1st magnet 10A in the meantime. Then, in order to obtain the position of the first magnet 10A, the process proceeds to step S9, the magnetic field values of the two virtual sensors VL straddling zero are linearly interpolated, for example, and the position where the magnetic field value becomes zero is determined by the first magnet 10A. Calculate as position.

  In the present embodiment, linear interpolation is performed between the magnetic field value of the virtual sensor VL3 and the magnetic field value of the virtual sensor VL4. In this embodiment, since the pitch P is 10 mm, the position of the virtual sensor VL3 is at a position of 20 mm, and the position of the virtual sensor VL4 is at a position of 30 mm. The position of the first magnet 10A is between 20 mm and 30 mm, and the final magnet position is calculated by performing linear interpolation between the magnetic field value of the virtual sensor VL3 and the magnetic field value of the virtual sensor VL4. ing.

  FIG. 8 is a diagram for explaining the linear interpolation for obtaining the position of the magnet. The vertical axis in FIG. 8 is an internal value of the microcomputer 40 indicating the magnitude of the magnetic field, and the horizontal axis indicates the coordinate position along the substrate BS. When the virtual sensor VL (n) at the position X0 has the magnetic field value Y0 and the virtual sensor VL (n + 1) at the position X1 has the magnetic field value Y1, in the coordinate system of FIG. 8, the virtual sensor VL (n) The coordinate position is at point a, and the coordinate position of the virtual sensor VL (n + 1) is indicated by point b. In the linear interpolation, the position of the magnet is obtained by obtaining the X position of the intersection of the straight line connecting the point a and the point b and the magnetic field value 0 line.

  Here, the position of X is obtained by X = X0 + Y0 × (X1-X0) / (Y0-Y1) (Formula 1). For example, when X0 = 20, X1 = 30, Y0 = 100, and Y1 = −200, applying this equation 1, the position of the magnet is 23.333, and the position of the first magnet 10A can be easily obtained. it can.

The method for detecting the position of the first magnet 10A when the first magnet 10A is within the effective detection length A of the magnetic sensor unit 100 has been described above. Next, the second magnet 10B is magnetic. A method for detecting the position of the second magnet 10B when the sensor unit 100 is within the range of the effective detection length A will be described.
FIG. 9 is a diagram for explaining the characteristics of the detection value (magnetic field value) of the magnetic sensor with respect to magnets having different magnetization directions. Here, the magnets having different magnetization directions are, for example, the second magnet 10B or the third magnet. This corresponds to the magnet 10C. The second magnet 10B and the third magnet 10C use neodymium φ5 × 6, similarly to the first magnet 10A.

  In FIG. 9, for example, when the second magnet 10B is at a position of 0 mm, the detected values of the magnetic sensors MS1 to MS4 are the magnetic field values when the characteristic curves of the magnetic sensors MS1 to MS4 shown in FIG. Is output. Moreover, when the 2nd magnet 10B exists in the position of 10 mm, the detected value of each magnetic sensor MS1-MS4 outputs the magnetic field value in case the characteristic curve of magnetic sensor MS1-MS4 shown in FIG. 9 is 10 mm. Thus, each magnetic sensor MS has a maximum detection value when the center of the second magnet 10B and the center of the magnetic sensor MS are at the same position. That is, as in the case of the first magnet 10A, the polarities are different, but the magnetic sensor MS is arranged to output the maximum detected value when the second magnet 10B and the magnetic sensor MS are closest to each other. ing.

As shown in FIG. 9, with the detection value of the magnetic sensor MS, it is difficult to detect the zero point of the magnetic field value by interpolation with a straight line or a curve and detect the position of the second magnet 10B. Therefore, the position of the second magnet 10B is detected by the same method as the method of detecting the position of the first magnet 10A.
That is, a difference is obtained every time one detection value of the magnetic sensor MS is skipped inside the microcomputer 40, and a magnetic field value of the virtual sensor located between the two skipped two magnetic sensors MS is generated. The position where the magnetic field value of the magnetic field distribution obtained by interpolating the values becomes zero is output as the position of the second magnet 10B.

  As shown in FIG. 9, the characteristic of the detection value (magnetic field value) of the magnetic sensor with respect to the second magnet is obtained by reversing the output of the characteristic of the detection value (magnetic field value) of the magnetic sensor with respect to the first magnet shown in FIG. It has been made to. That is, in the case of the first magnet 10A, the maximum value of the magnetic sensor MS is on the plus side, and in the case of the second magnet 10B, the maximum value of the magnetic sensor MS appears on the minus side. For this reason, discrimination between the first magnet 10A and the second magnet 10B is possible. The reference magnet discriminating unit uses this characteristic as will be described later. It is determined whether or not the magnet specified by the magnet specifying unit 43 is a reference magnet.

  FIG. 10 is a diagram for explaining the characteristics of the difference value between the detection values of two skipped magnetic sensors when magnets having different magnetization directions face the magnetic sensor. The characteristics shown in FIG. 10 are obtained from the detection values of the respective magnetic sensors shown in FIG. 9. However, when the first magnet 10A shown in FIG. The characteristic of the difference value of each detection value of the magnetic sensor MS is a characteristic obtained by inverting the sign. The characteristic curve shown in FIG. 10 shows the characteristics of the virtual sensor VL1.

  As described above, when detecting the position of the second magnet 10B, the characteristics of the detection value of the magnetic sensor MS and the characteristics of the magnetic field value of the virtual sensor VL are reversed from those in the case of detecting the position of the first magnet 10A. The position detection of the second magnet 10B can be obtained by the same method as the position detection of the first magnet 10A.

  When detecting the position of the second magnet 10B, the magnetic sensor MS that has detected the maximum value on the minus side is specified, and the virtual sensor VL that is closest to the magnetic sensor MS is specified. Further, it is determined whether or not the magnetic field value crosses the zero value between the specified virtual sensor VL and the virtual sensors VL before and after the specified virtual sensor VL. Then, if two virtual sensors straddling zero can be specified, the second magnet 10B exists between them, and linear interpolation of the magnetic field values of the two virtual sensors VL is performed to obtain the position of the second magnet 10B.

  For example, when the magnetic sensor MS8 detects the maximum negative value among the magnetic sensors MS2 to MS10 within the effective detection length A, the virtual sensor closest to the magnetic sensor MS8 is the virtual sensor VL7. The polarities of the detection values of the sensor VL6 and the virtual sensor VL7 and the polarities of the detection values of the virtual sensor VL7 and the virtual sensor VL8 are respectively compared. If the polarities are reversed, the magnetic field value is between zero and the second magnet 10B is present.

  If the magnetic field value of the virtual sensor VL6 is negative, the magnetic field value of the virtual sensor VL7 is positive, and the magnetic field value of the virtual sensor VL8 is positive, the polarity of the magnetic field value of the virtual sensor VL6 and the polarity of the magnetic field value of the virtual sensor VL7 are reversed. Therefore, there is the second magnet 10B in the meantime. Then, linear interpolation of the magnetic field values of the virtual sensor VL6 and the virtual sensor VL7 is performed.

  In this embodiment, since the interval between the virtual sensors VL is 10 mm, it can be seen that the position of the virtual sensor VL6 is 50 mm from the virtual sensor VL1 at the position 0 mm. A value obtained by linear interpolation of the magnetic field values of the virtual sensor VL6 and the virtual sensor VL7 is added to this value to obtain the final position of the second magnet 10B.

  The linear interpolation is the same as the case where only the first magnet 10A is located within the range of the effective detection length A, for example, the magnetic field value of the virtual sensor VL6. When Y0 is −100 and the magnetic field value Y1 of the virtual sensor VL7 is 200, the position of X can be obtained by X = X0 + Y0 × (X1−X0) / (Y0−Y1) (Equation 1). When X0 = 50, X1 = 60, Y0 = −100, and Y1 = 200 are applied to Equation 1, the position X of the second magnet 10B is 53.333, and the position of the second magnet 10B can be easily obtained. Can do.

FIG. 11A is a diagram for explaining the positional relationship taken by the magnets within the effective detection length A of the magnetic sensor unit in the position detection device according to the first embodiment of the present invention, and FIG. In the position detection apparatus shown, it is a figure at the time of changing the relative position of a magnet and a magnetic sensor. In the present embodiment, there are three magnets, and the inter-magnet distances L <b> 1 and L <b> 2 between adjacent magnets are set to 70 mm, which is shorter than the effective detection length A of the magnetic sensor unit 100.
For this reason, the positional relationship that the magnet takes within the effective detection length A of the magnetic sensor unit 100 is as follows.
Case 1: As shown in FIG. 11A (Case 1), only the first magnet 10A as the reference magnet is located.
Case 2: When the first magnet 10A and the second magnet 10B are positioned as shown in FIG. 11A (case 2).
Case 3: As shown in FIG. 11A (Case 3), only the second magnet 10B is located.
Case 4: As shown in FIG. 11B (case 4), the second magnet 10B and the third magnet 10C are positioned.
Case 5: When only the third magnet 10C is positioned as shown in FIG. 11B (case 5).

  The position detection device 1 includes a plurality of magnets. Since the first magnet 10A, which is a reference magnet, has a different magnetization direction from other magnets, the reference magnet determination unit 44 determines that the first magnet 10 is located within the effective detection length A. The magnet specified by the magnet specifying unit 43 can be determined as the reference magnet. Accordingly, when the power is turned on, in the case 1 or 2, the first magnet 10 </ b> A that is the reference magnet is located within the effective detection length A. It can be determined that the identified magnet is the reference magnet. In addition, you may comprise so that the magnet specific | specification part 43 may serve as the function of the reference | standard magnet discrimination | determination part 44. FIG.

  However, in other cases, the reference magnet discriminating unit 44 cannot discriminate which magnet among the plurality of magnets the magnet specifying unit 43 is the target of position detection. For example, in the present embodiment in which the number of magnets is three, in case 3 and case 5, the magnet specifying unit 43 specifies the magnet for position detection from the detection value of each magnetic sensor MS, The position signal generator 42 can output the position of the magnet from the reference position (0 mm). The reference magnet determination unit 44 can determine that the magnet whose position is to be detected by the magnet specifying unit 43 is not the reference magnet, but determines whether the magnet is the second magnet 10B or the third magnet 10C. Can not do it. This is because the magnetization directions of the second magnet 10B and the third magnet 10C with respect to the moving direction are the same. When the number of magnets is greater than 3, even when two magnets having the same magnetization direction are positioned within the effective detection length A, the position detection device 1 determines which magnet these magnets are. Can not.

  For this reason, in this embodiment, when the reference magnet discriminating unit 44 cannot discriminate the reference magnet as the position detection target magnet when the power is turned on, at least the reference magnet discrimination is performed from the magnet movement signal generating unit 47 through the magnet moving mechanism 60. The position of the magnet is relatively moved until the unit 44 can determine the reference magnet as the magnet whose position is to be detected. For example, in case 3 where the reference magnet cannot be determined when the power is turned on, the magnet is moved as an initial operation until the first magnet 10A, which is the reference magnet, can be detected within the effective detection length A. Specifically, the first magnet 10A is moved until it faces the magnetic sensor MS2 at the reference position 0 mm or the magnetic sensor MS10 at the position 80 mm. Thereafter, the position detection device 1 detects a position associated with the movement of the magnet. Alternatively, the position signal generator 42 calculates the position of the magnet within the effective detection length A when the power is turned on, stores the position in the memory, and then moves the magnet until the position of the reference magnet can be detected. Accordingly, it is possible to calculate the position of the reference magnet when the power is turned on from the distance moved and the position stored when the power is turned on.

  Next, a position detection method in this embodiment will be described. In case 1 where the first magnet 10A as the reference magnet is within the effective detection length A of the magnetic sensor unit 100 and the position of the first magnet 10A can be detected when the power is turned on, the first magnet as the reference magnet The position of the magnet 10 </ b> A is set as the output value of the position detection device 1. Next, in the case 2 where the first magnet 10A and the second magnet 10B are located within the effective detection length A, the position of the first magnet 10A that is the reference magnet is prioritized, and the first magnet 10A. Is the output value of the position detection device 1. Hereinafter, the position of the first magnet 10 </ b> A is set as the output value of the position detection device 1.

  Next, in the case 3 where the first magnet 10A comes out of the effective detection length A and only the second magnet 10B can be detected, the magnet specifying unit 43 comes out from the case where the first magnet 10A is the case 2. By storing this, it is specified that the position-detectable magnet is the second magnet 10B. Then, the position signal generation unit 42 obtains the position of the second magnet 10B, and the reference magnet position calculation unit 45 further determines the value by the distance L1 between the magnets of the first magnet 10A and the second magnet 10B. A value obtained by adding 70 mm is set as the output value of the position detection device 1 as the position of the first magnet 10A. Adding 70 mm, which is the distance L1 between the magnets, to the position of the second magnet 10B means that the first magnet 10A is outside the range of the effective detection length A of the magnetic sensor unit 100, but the second magnet The position of the first magnet 10A is obtained from the position of 10B.

  Next, in the case 4 where the magnet moves and the second magnet 10B and the third magnet 10C are positioned within the effective detection length A, the second magnet 10B is given priority, and the case 3 is the same. The position signal generator 42 determines the position of the second magnet 10B, and the reference magnet position calculator 45 further includes the inter-magnet distance L1 between the first magnet 10A and the second magnet 10B. A value obtained by adding 70 mm is set as an output value of the position detection device 1.

  Next, in the case 3 where the second magnet 10B comes out of the effective detection length A and only the third magnet 10C is located within the effective detection length A, the magnet specifying unit 43 is configured so that the second magnet 10B is the case. By memorizing that it has escaped from the case of 4, it is specified that the position-detectable magnet is the third magnet 10C. Then, the position signal generation unit 42 obtains the position of the second magnet 10B, and the reference magnet position calculation unit 45 further determines the value by the distance L1 between the magnets of the first magnet 10A and the second magnet 10B. A value obtained by adding a certain 70 mm and 70 mm, which is the distance L2 between the magnets of the second magnet 10B and the third magnet 10C, is used as the output value of the position detection device 1. For example, when the position of the third magnet 10C is 30 mm, the output value of the position detection device 1 is 170 mm.

  FIG. 12 is a diagram illustrating a case where the number of magnets is four in the position detection device according to the first embodiment of the present invention. In the position detection device shown in FIG. 12, a fourth magnet 10D is further added to the position detection device shown in FIGS. 11A and 11B. Also in this case, the distances L1, L2, and L3 between the adjacent magnets are set to be equal to or less than the effective detection length A of the magnetic sensor unit 100, respectively. The total effective detection length Ltotal of the position detection device shown in FIG. 12 is obtained by adding the effective detection length A of the magnetic sensor unit 100 and the distance between all magnets located at both ends, which is the sum of the distances between adjacent magnets. The length, that is, Ltotal = A + L1 + L2 + L3. Thus, in this embodiment, the total effective detection length Ltotal as the position detection device can be extended by increasing the number of magnets, and the number is not limited as long as the number of magnets is three or more.

  When there is one magnet, the total effective detection length Ltotal of the position detection device 1 is equal to the effective detection length A of the magnetic sensor unit 100. However, the total effective detection length Ltotal of the position detection device 1 can be specified as a reference magnet, for example, by changing the direction of magnetization, as in the present embodiment, by changing the direction of magnetization. This is a length obtained by adding the effective detection length A of the magnetic sensor unit 100 and the distance between all the magnets located at both ends, which is the sum of the distances between adjacent magnets. When the power is turned on, it is necessary to move the magnet until the reference magnet is once determined. However, the total effective detection length Ltotal of the position detection device 1 is taken into account by taking into account the distance between the magnets stored in advance. Can be stretched.

(Modification of the first embodiment)
In the first embodiment, in order to determine a reference magnet from among a plurality of magnets, a case where a magnet having a magnetization direction different from that of another magnet is used as an example of movement is described. In order to do so, a magnet having a different magnetization strength from other magnets may be used. When magnets having different magnetization strengths are used, it is desirable to use magnets having such strength that the difference in the maximum value of the detection values of the magnetic sensor can be sufficiently discriminated when each magnet is opposed to the magnetic sensor MS. In either case, the magnetic sensor MS needs to have the magnet and the magnetic sensor arranged so as to output the maximum detection value when the magnet is closest.

  In the first embodiment, the first magnet 10A located at the rightmost end is the reference magnet. However, the reference magnet is not necessarily the rightmost end magnet, and is the magnet located at the leftmost end or the center. There may be. Also in this case, as the reference magnet, a magnet having a magnetization direction different from that of the other plural magnets or a magnet having a magnetization intensity different from that of the other plural magnets may be used.

(Second Embodiment)
FIG. 13 is a diagram illustrating the arrangement relationship between magnets and magnetic sensors in the position detection device according to the second embodiment of the present invention. In the example shown in FIG. 13, the same magnetic sensor unit 100 as that in the first embodiment is used, and the plurality of magnets are arranged so that their magnetization directions are aligned in the same direction. In the illustrated example, the number of magnets is four, but it may be three or more. The arrangement relationship between the magnet and the magnetic sensor shown in FIG. 13 is the same as the arrangement of the magnet and the magnetic sensor of the first embodiment shown in FIG. It corresponds to the same direction as the direction. Further, the inter-magnet distances L1, L2, and L3 between adjacent magnets are set to be equal to or less than the effective detection length A of the magnetic sensor unit 100, respectively.

  In 2nd Embodiment, the magnet arrange | positioned at both ends is functioned as a reference | standard magnet. In the example shown in FIG. 13, the first magnet 10A located at the rightmost end or the fourth magnet 10D located at the leftmost end serves as a reference magnet. When the inter-magnet distances L1, L2, and L3 between adjacent magnets are 70 mm, in this embodiment, when the power is turned on, a case where one magnet is located within the effective detection length A of the magnetic sensor unit 100; Although there are cases where two magnets are located, since the plurality of magnets are all magnetized in the same direction, the reference magnet discriminating unit 44 has identified the magnet identifying unit 43 as a position detection target in any case. A magnet cannot be identified as a reference magnet.

For this reason, in this embodiment, the position is detected by the following method.
(1) First, the magnet movement signal generation unit 47 sends a signal for relatively moving the magnets to the magnet moving mechanism 60 until all the magnets are not positioned within the effective detection length A of the magnetic sensor unit 100. When the magnet and the magnetic sensor MS are in the state shown in FIG. 13 when the power is turned on, for example, the magnet is moved to the left in the drawing, and the first magnet 10A is moved to the left until the position deviates from the effective detection length A. Move. Whether or not the first magnet 10A has deviated from the effective detection length A can be determined by the fact that the magnet specifying unit 43 can no longer specify a magnet for position detection.

  (2) Next, the magnet movement signal generation unit 47 sends a signal to the magnet movement mechanism 60 to relatively move the magnet in the opposite direction, that is, in the right direction on the page. As a result, the first magnet 10 </ b> A at the rightmost end moves in the right direction and moves into the effective detection length A of the magnetic sensor unit 100. Then, since the magnet specifying unit 43 can specify the first magnet 10A that first enters the effective detection length A as a position detection target magnet, the reference magnet determining unit 44 first sets the magnet specifying unit 43. Is detected as the reference magnet, that is, the first magnet 10A. The position detection method after detecting the reference magnet is the same as the method described in the first embodiment.

  When the fourth magnet 10D at the leftmost end is used as a reference magnet, the direction in which the magnet is moved is relatively moved to the right until the fourth magnet 10D is not positioned within the effective detection length A, and then By moving the magnet to the left, the magnet first identified by the magnet identifying unit 43, that is, the fourth magnet 10D may be detected as the reference magnet.

  In the second embodiment, two magnets located at both ends of the plurality of magnets are used as reference magnets. In this method, the reference magnet is discriminated only by the arrangement relationship of a plurality of magnets regardless of the magnetization direction and the magnetization intensity of the magnets. Therefore, in the second embodiment, the magnetization directions of the plurality of magnets do not have to be the same, and may be different. Furthermore, the same applies to the strength of magnetization of each magnet, and the strength may be different. In the present embodiment, as in the first embodiment, the number of magnets is not limited as long as it is three or more.

(Third embodiment)
FIG. 14 is a diagram illustrating a positional relationship between a magnet and a magnetic sensor in a position detection device according to a third embodiment of the present invention. In this embodiment, the distances between adjacent magnets are all different, and any magnet can be a reference magnet, as will be described later. In the example shown in FIG. 14, the magnetic sensor unit 100 is the same as that of the first embodiment, and the number of magnets is five. However, the number of magnets is not limited to this. The intermagnet distance L1 between the first magnet 10A and the second magnet 10B, the intermagnet distance L2 between the second magnet 10B and the third magnet 10C, which is the intermagnet distance between adjacent magnets, and the third The distance L3 between the magnet 10C and the fourth magnet 10D and the distance L4 between the fourth magnet 10D and the fifth magnet 10E are equal to or less than the effective detection length A of the magnetic sensor unit 100, respectively. And each length is set differently. For example, L1 = 75 mm, L2 = 70 mm, L3 = 65 mm, and L4 = 60 mm are set, and the position detection device 1 stores the values of these inter-magnet distances L1, L2, L3, and L4 in advance. ing. Moreover, although the magnetization direction of each magnet is assumed to be the same direction, it may be different as will be described later.

  In this embodiment, when the power is turned on, there are a case where one magnet is located and a case where two magnets are located within the effective detection length A of the magnetic sensor unit 100, but a case where one magnet is located. In this case, since the plurality of magnets are all magnetized in the same direction, the reference magnet discrimination unit 44 cannot discriminate the magnet whose position is to be detected by the magnet identification unit 43 as a reference magnet. On the other hand, in the case where two magnets are positioned within the effective detection length A of the magnetic sensor unit 100, the reference magnet determination unit 44 determines the distance between these magnets based on the distance between the magnets of which the magnet specifying unit 43 is the target of position detection. Two magnets can be identified as reference magnets. The distance between the two magnets within the effective detection length A can be calculated from the positions of the respective magnets output by the position signal generator 42. Then, the reference magnet discrimination unit 44 can discriminate two magnets that match the stored distance between the magnets as the reference magnet.

  For example, in the example shown in FIG. 14, the reference magnet discriminating unit 44 determines that these two magnets are the second magnet 10B and the third magnet 10C because the distance between the two magnets is 70 mm. Can be determined. Then, either the second magnet 10B or the third magnet 10C can be used as a reference magnet. For example, when the third magnet 10C is a reference magnet, the distance d2 between the third magnet 10C and the second magnet 10B and the second magnet 10B and the second magnet 10B are set to the value dmm of the position of the third magnet 10C. A value obtained by summing the distance L1 between the magnets of one magnet 10A can be output as the position of the first magnet 10A. Alternatively, when the second magnet 10B is used as the reference magnet, a value obtained by adding the distance L1 between the second magnet 10B and the first magnet 10A to the value of the position of the second magnet 10B is set to the first magnet 10B. It can be output as the position of the magnet 10A.

  In the case where only one magnet is located within the effective detection length A of the magnetic sensor unit 100 when the power is turned on, the magnet movement signal generation unit 47 is compared with the magnet movement mechanism 60, and the magnet identification unit 43 is the position detection target. A signal for moving the magnet is transmitted until two magnets can be identified. The moving direction can be arbitrarily determined in advance, and the moving distance is equal to or less than the maximum inter-magnet distance Lmax. If the magnet specifying unit 43 can specify two magnets whose position is to be detected, the reference magnet discriminating unit 44 can use any of the magnets as a reference magnet and perform the subsequent measurements by the method described above.

  For this reason, in the case where only one magnet is positioned within the effective detection length A when the power is turned on, if it is desired to know the position of the magnet, the position signal generator 42 first obtains the position d of the magnet, For example, if the position is less than half the effective detection length A, the magnet is moved in the left direction until the positions of the two magnets can be detected. Then, by calculating the distance between the two magnets, it is possible to identify the magnet that was initially positioned within the effective detection length A. Accordingly, the position of the first magnet 10A can be output by adding the distance between the magnets of the magnets located on the right side of the magnet to the value of the position d of the magnet obtained first.

Thus, in this embodiment, a magnet is specified using a distance between magnets that is set in advance and whose distance is known. For this reason, all the magnets can become reference magnets. Therefore, the position of each magnet can be calculated only by relatively moving the magnets by a length equal to or less than half the effective detection length A of the magnetic sensor unit 100 without specifying a magnet to be a reference magnet. In the third embodiment, for example, when the number of magnets is N, the distance between adjacent magnets in order from the first magnet 10A side is L1, L2, L3..., Ln-1, Ln. ... L _N-1 (Ln-1 is the distance between the magnets of the nth and n-1th magnets), L1 to L _N-1 are all different values and all effective detection The length Ltotal is Ltotal = effective detection length A + (L1 + L2 + L3 +... + Ln-1 + Ln +... + L _N-1 ).

If necessary, the distance between the two magnets can be measured by moving the magnet in one direction only by a relative distance not more than half of the maximum inter-magnet distance Lmax (<A). advance between known magnet distance L1, L2, L3 ···, with _{Ln-1, Ln ··· L n} -1, it is possible to specify the n-th magnet. When the nth magnet is positioned within the effective detection length A of the magnetic sensor unit 100, the output of the position detection device 1 is the position d + (L1 + L2 + L3 +... + Ln) of the nth magnet. -1).

  In the third embodiment, each magnet can be specified using the distance between adjacent magnets. For this reason, it is only necessary to be able to calculate the inter-magnet distances of a plurality of magnets irrespective of the magnetization direction and the magnetization strength of the magnets. Therefore, in the third embodiment, as in the second embodiment, the magnetization directions of the plurality of magnets do not have to be the same, and may be different. The same applies to the strength of magnetization of each magnet, and the strength may be different.

(Fourth embodiment)
FIG. 15 is a diagram illustrating a positional relationship between a magnet and a magnetic sensor in a position detection device according to a fourth embodiment of the present invention. In the fourth embodiment, the same magnetic sensor unit 100 as in the first embodiment is used, but a plurality of magnet sets S ₁ to S _M (M is an integer, and the number M of magnetic sensors MS is the same as Provided separately). S _M from each magnet set S _1, and the reference magnet 10Re _m when the number of magnets for example, 12, the end portion, for example, disposed at the right end portion included in each magnet set, the magnet 10A of the first (second) _A sub-magnet set consisting of eleven magnets from _m to eleventh (Kth) magnet 10K _m is included. In each of the magnet sets S ₁ to S _M , the reference magnet 10Re _m and the first magnet 10A _m to the eleventh (Kth) magnet 10K _m of the sub magnet set are in the direction of magnetization with respect to the moving direction. Are different.

The arrangement of the first magnet 10A _m to the eleventh magnet 10K _m of each sub-magnet set is, for example, the same arrangement as in the third embodiment, and the first magnet 10A _m and the second magnet 10B. magnets distance between _m L1, magnets distance L2 between the second magnet 10B _m and third magnet 10C _m, third magnet 10C _m and the magnet distance L3 between the fourth magnet 10D _m, hereinafter the same Further, when the distance between the ninth magnet 10I _m and the tenth magnet 10J _m is L9, and the distance between the tenth magnet 10J _m and the eleventh magnet 10K _m is L10, the distance L1 between each magnet. To L10 are set to be equal to or less than the effective detection length A of the magnetic sensor unit 100, and are set to different lengths so as to have an identifiable difference. Then, in this embodiment, the distance Lx between the sequence and ends magnet sub magnet assembly in S _M from each magnet set S ₁ are all configured the same.

Further, except for the reference magnet 10Re ₁ magnet set S ₁ of the rightmost, for magnet distance between the magnets located on both sides of the reference magnet 10Re _m from each magnet set S ₂ with the reference magnet 10Re _m of S _M, m LB _m-1 the magnet distance between the K-th magnet 10K _m-1 at the top left of the reference magnet 10Re _m and m-1 th set of magnets set S _m-1 of the magnet assembly S _m of th set, If a magnet distance between the first magnet 10A _m of the same magnet set S _m was LF _m and the reference magnet 10Re _m of the magnet assembly S _m of m-th set, LB _m-1 and LF _m are both magnetic sensor unit It is set below the effective detection length a of 100, and the combination length and length of the magnet distance LB _m-1 of the magnet distance LF _m is set to different combinations in all of the reference magnet 10Re _m. The inter-magnet distance LF ₁ between the first set of reference magnets 10 Re ₁ and the first set of first magnets 10 A ₁ located at the rightmost end is set to be equal to or less than the effective detection length A of the magnetic sensor unit 100. The combination of the inter-magnet distances LF _m and LB _m−1 before and after each reference magnet 10Re _m including the reference magnet 10Re ₁ and the first magnet 10A _m of the sub magnet set in each magnet set S ₁ to S _M for K-th magnet distance L1 from L10 array of magnets 10K _m from also stored in advance in the memory of the microcomputer 40.

Thus, the reference magnet 10Re _m of m-th set, since the direction of magnetization around the magnet different, the reference magnet determination unit 44 is able to determine the magnet magnetic identification unit 43 has identified as a reference magnet, further, by calculating the magnet distance LF _m and LB _m-1 of both sides of the magnet of the reference magnet 10Re _m of m-th set from the position output of the position signal generator 42, a reference magnet 10Re _m of m-th set Can be determined. The first set of reference magnets 10Re ₁ is different from the other reference magnets 10Re ₂ to 10Re _{M in} that there is no magnet on the right side and only the first magnet 10A ₁ on the left side exists. or right side by recognizing that there is no magnet, it is possible to identify a first set of reference magnet 10Re _1.

In the present embodiment, when power is turned on, and the reference magnet 10Re _m, the reference magnet 10Re _m is either side of magnet (m-1) th set K-th magnet set S _m-1 of the magnet 10K _m-1 When the three magnets of the first magnet 10A _m of the _m- th magnet set Sm are simultaneously positioned within the effective detection length A of the magnetic sensor unit 100, the reference magnet 10Re _m is identified, The position can be calculated. However, such a case is rare, and usually one or two magnets exist in the effective detection length A of the magnetic sensor unit 100 in many cases. In such a case, a magnet movement signal generator 47 through the magnet moving mechanism 60, the magnet at least the magnet identifying unit 43 has identified as a target of the detection position, to the reference magnet determination unit 44 can determine, based magnet 10Re _m, Move the position of the magnet relatively.

Reference magnet determination unit 44 and are able to determine the one reference magnet 10Re _m, further, the K-th m-1 th set is a right magnets of the reference magnet 10Re _m of the magnet 10K _m-1 It is necessary to specify the reference magnet 10Re _m by calculating the inter _- magnet distance LB _m-1 and the inter-magnet distance LF _m with the m-th set of first magnets 10A _m on the left side. Therefore, the magnet through a mobile signal generating section 47 magnet moving mechanism 60 from the reference magnet 10Re _m and the reference magnet 10Re _m and m th set first magnet 10A _m and at the same time the magnetic sensor unit effective detection length of 100 A of moves the magnet until located, calculates the distance LF _m between the two magnets, further, the reference magnet 10Re _m and the K-th magnet 10K _m-1 of the reference magnet 10Re _m and m-1 th set At the same time, the magnet is moved until it is located within the effective detection length A of the magnetic sensor unit 100 to calculate the distance LB _m-1 between the two magnets. Thus, a combination of a magnet distance LB _m-1 and the magnet distance LF _m before and after the reference magnet 10Re _m, the reference magnet determination unit 44, whether the reference magnet 10Re _m is the reference magnet of which the magnet assembly Can be determined.

In the present embodiment, since the M reference magnet 10Re _m from a plurality of magnets set S ₁ corresponding to S _M are present, if a particular one reference magnet 10Re _m, the magnet in the subsequent sub-magnets in the set, It is possible to specify the magnet in which magnet set and to calculate the position of the magnet with high accuracy. Therefore, for example, the position of the reference magnet 10Re ₁ of the first magnet set S ₁ can be output from the position of the magnet positioned within the effective detection length A of the magnetic sensor unit 100.

FIG. 16 is a diagram for explaining how to obtain the position of the magnet in the position detection device according to the fourth embodiment of the present invention. For example, assume that the number of magnet sets is 100, and each magnet set includes a total of 12 magnets including one reference magnet and 11 magnets as sub magnet sets. The effective detection length A of the magnetic sensor unit 100 is 80 mm, and the inter-magnet distances L1 to L10 of the sub magnet sets are, for example, L1 = 75 mm, L2 = 70 mm, L3 = 65 mm,... L9 = 35 mm, L10 It is assumed that the difference is set to 30 mm and 5 mm. In this case, both ends magnet distance Lx of each sub-sets of magnets, i.e., the first magnet 10A _m and across the magnet length Lx of the K-th magnet 10K _m located at both ends of each sub-magnet set, Lx = L1 + L2 + L3 + ... + L9 + L10 and Lx = 525 mm.

Further, the inter-magnet distance LF _m between the m-th set of reference magnets 10Re _m and the m-th set of first magnets 10A _m is sequentially 75 mm, 70 mm, 65 mm, 60 mm, 55 mm, 50 mm, 45 mm, 40 mm, 35 mm, and 30 mm. Similarly, the inter-magnet distance LB _m-1 between the _m- th set of reference magnets 10Re _m and the (m-1) th set of the K-th magnet 10K _m-1 is sequentially set to 75 mm, 70 mm, 65 mm, and 60 mm. , 55 mm, 50 mm, 45 mm, 40 mm, 35 mm, and 30 mm, there are 100 possible combinations of the inter-magnet distance LF _m and the inter-magnet distance LB _m−1 . Further, the first set of reference magnets 10Re _{1 at} the rightmost end can be identified by the absence of the right magnet. Accordingly, the distance LF ₁ between the magnets is 75 mm, and 99 combinations of the distances LF _m between the magnets LF _m and the distances LB _m-1 between the reference magnets Re ₂ to Re ₁₀₀ are 99 values from the larger numerical value. Do a combination of Thus, the magnet distance LB ₉₉ between the front and rear magnet leftmost reference magnet 10Re ₁₀₀ is 35 mm, LF ₁₀₀ becomes 30 mm.

At this time, the total effective detection length Ltotal of the position detection device 1 is
Ltotal = A + 100 subset Lx + (addition value from LF ₁ to LF ₁₀₀ ) + (addition value from LB ₁ to LB ₉₉ )
= A + 100 * Lx + [75 + 10 * (75 + 70 + 65 + ... + 30) -30] + {10 * (75 + 70 + 65 + ... + 30) -30}
= 80 + 52500 + 75 + 5250-30 + 5250-30
= 63095 mm.
Here, the third to fifth terms of the third expression are the sum of the inter-magnet distances LF _m , and the sixth and seventh terms are the sum of the inter-magnet distances LB _m−1 .

Then, as shown in FIG. 16, if the position of the second magnet 10B ₅₄ of the sub-magnet set of the _54th magnet set S54 is dmm, the first magnet is moved from the 0 mm position of the magnetic sensor unit 100. The position (distance) Z of the reference magnet 10Re ₁ of the set S ₁ is
Z = d + L1 + {LF ₅₄ + (distance from 10Re ₁ to 10Re ₅₄ )}
= D + L1 + {(Length of 53 sets of distance Lx between magnets at both ends of subset) + (Addition value of LF ₁ to LF ₅₄ ) + (Addition value of LB ₁ to LB ₅₃ )}
= D + 75 + [53 × 525 + [75 + 10 × (75 + 70 + 65 + 60 + 55) + 3 × 50]] + {5 × (75 + 70 + 65 + 60 + 55 + 50 + 45 + 40 + 35 + 30) + (75 + 70 + 65)}
= D + 34210 mm.
In the present embodiment, since the distance between the first set of reference magnets 10Re ₁ and the reference magnets 10Re _m of each magnet set can be calculated in advance, each of the reference magnets 10Re _m calculated from the distance between the magnets of each magnet. The position may be stored in the memory of the microcomputer 40 in advance. This facilitates the calculation of the position.

As described above, in the present embodiment, a plurality of magnet sets having a plurality of magnets are provided, and the end magnets of each magnet set are configured to be distinguishable from other magnets as reference magnets. Since the reference magnet is discriminated by making the relationship between the distances between the front and rear magnets located on both sides of the magnetic field different from each other, for example, about 10 ³ times the effective detection length A of the magnetic sensor unit 100 The detection distance for position detection can be expanded with high accuracy up to

If this embodiment is generalized, the arrangement of magnets is as follows.
(1) Arrange a plurality of magnet sets S ₁ to S _M having a plurality of magnets.
(2) Each magnet set is composed of a reference magnet and a sub-magnet set. The reference magnet is placed at the position of the end of each magnet set, for example, by changing the magnetization direction or changing the strength of magnetization. It can be distinguished from the magnet of the magnet set.
(3) The reference magnets of each magnet set are arranged so that the combination of the distances between the magnets with the magnets located on both sides is different for each reference magnet.
(4) All the distances between the magnets are within the effective detection length A of the magnetic sensor unit 100.

In the fourth embodiment, the inter-magnet distances of the sub-magnet sets constituting each magnet set are configured to have different inter-magnet distances as in the third embodiment. As in the embodiment, all may have the same distance between magnets. In this case, the movement by in accordance with the movement of the magnet, after identifying the reference magnet 10Re _m, each sub-sets of magnets is stored whether exited many pieces from the effective detection length A of the magnetic sensor unit 100 in the memory of the microcomputer And the position of a predetermined magnet can be detected.

(Fifth embodiment)
In the first embodiment, since the virtual sensor VL is generated by obtaining the difference value for each of the two skipped magnetic sensors MS, the number of virtual sensors VL is two less than the number of magnetic sensors, When the magnetic sensors are arranged at an equal pitch P of 10 mm, the interval between the virtual sensors VL is also 10 mm, which is the same as the interval between the magnetic sensors MS. In the first embodiment, when linear interpolation is performed, it is desirable that the interval of ± 10 mm from the zero point of the magnetic field value (the interval of the magnetic sensor MS) is a straight line. As shown by the symbol C in FIGS. 5 and 10, the linearity is deteriorated. Therefore, an error occurs when linear interpolation is performed using a value having poor linearity.

  In the fifth embodiment, for example, it is possible to detect the position of the magnet with higher accuracy even by linear interpolation that is easier to calculate than in the first embodiment. For this reason, in the fifth embodiment, in addition to the method of obtaining the difference every time the detection value of the magnetic sensor MS of the first embodiment is skipped, the difference value of the detection values adjacent to the magnetic sensor MS is also obtained. Yes. That is, in addition to the (M-2) first group of virtual sensors VL obtained in the first embodiment, a difference value between detection values of two adjacent magnetic sensors is calculated, and this difference value is used as a magnetic field value. The (M−1) second group of virtual sensors VL located between two adjacent magnetic sensors are used. In the present invention, a plurality of virtual sensors positioned between two adjacent magnetic sensors MS are referred to as a second group of virtual sensors.

Hereinafter, for example, as shown in FIG. 11A, a method for detecting the position of the first magnet 10 </ b> A in the case 1 where only the first magnet 10 </ b> A is positioned within the effective detection length A of the magnetic sensor unit 100 will be described. .
FIG. 17 is a diagram for explaining the characteristics of the difference value between the detection values of two adjacent magnetic sensors when the first magnet faces the magnetic sensor. FIG. 18 shows the position of the magnetic sensor. It is a figure which shows the position of the virtual sensor which combined the 1st group and the 2nd group. In FIG. 17, the vertical axis represents the internal value of the microcomputer 40 representing the magnitude of the magnetic field, and the horizontal axis represents the position along the substrate BS.

  Specifically, the difference value of “the detection value of the magnetic sensor MS2−the detection value of the magnetic sensor MS1” is obtained, and this difference value is obtained as a virtual sensor VL1 located at a position of −5 mm between the magnetic sensor MS1 and the magnetic sensor MS2. A difference value of “detection value of magnetic sensor MS3−detection value of magnetic sensor MS1” is obtained, and this difference value is a virtual sensor at a position of 0 mm located between magnetic sensor MS1 and magnetic sensor MS3. The difference value of “the detection value of the magnetic sensor MS3−the detection value of the magnetic sensor MS2” is obtained as the magnetic field value of VL2, and this difference value is obtained from the virtual sensor VL3 located 5 mm between the magnetic sensor MS2 and the magnetic sensor MS3. A difference value of “detection value of magnetic sensor MS4−detection value of magnetic sensor MS2” is obtained as a magnetic field value, and this difference value is an intermediate value between magnetic sensor MS2 and magnetic sensor MS4. A field value of the virtual sensor VL4 located 10 mm, sequentially calculates the magnetic field values to the virtual sensor VL19.

  Here, the even-numbered nine virtual sensors VL2, VL4, VL6... VL18 are generated from the two skipped magnetic sensors MS obtained in the first embodiment. It corresponds to the virtual sensor VL. The characteristics of the first group of virtual sensors VL have the same characteristic curves as the characteristic curves shown in FIG. The odd-numbered ten virtual sensors VL1, VL3, VL5... VL19 are generated from the two adjacent magnetic sensors MS and correspond to the second group of virtual sensors VL.

  The characteristic shown in FIG. 17 is obtained from the detection value of the magnetic sensor MS2 and the detection value of the magnetic sensor MS3 shown in FIG. 4, and shows the characteristic of the virtual sensor VL3. The virtual sensor VL3 is located at a position of 5 mm, which is an intermediate position between the magnetic sensor MS2 and the magnetic sensor MS3. The magnetic field value becomes zero at the position of 5 mm, and the magnetic field value before and after the zero point changes linearly. Yes. Similarly, the characteristic of the virtual sensor VL1 belonging to the second group is a characteristic obtained by shifting the characteristic of the virtual sensor VL3 of FIG. 17 by 10 mm in the minus direction of the substrate BS, and the characteristic of the virtual sensor VL5 is the virtual sensor VL3 of FIG. The characteristic is shifted by 10 mm in the plus direction of the substrate BS.

  Accordingly, in the fifth embodiment, nine even-numbered first group virtual sensors VL having the same characteristics as those shown in FIG. 5 and ten characteristics having the same characteristics as those shown in FIG. The odd-numbered second group of virtual sensors VL are generated at a pitch P ′ having an interval of 5 mm as shown in FIG. This is the same as 19 magnetic sensors arranged at intervals of 5 mm, and the linear characteristics in the section of ± 5 mm from the zero point of the magnetic field value can be used. The position of one magnet 10A can be detected. Further, the effective detection length A ′ is 90 mm from 18 × pitch P ′. From the effective detection length A in the first embodiment or the effective detection length A ′ in the fifth embodiment, the effective detection length of the magnetic sensor unit 100 is a virtual sensor located at both ends along the arrangement direction of the magnetic sensors MS. It can be defined as equivalent to the distance between.

In the fifth embodiment, the method for detecting the position of the first magnet 10A by linear interpolation is the same as in the first embodiment.
First, the magnetic sensor MS that outputs the maximum detected value from among the plurality of magnetic sensors MS of the magnetic sensor unit 100 is specified. As a result, the approximate position of the magnet can be known, and it becomes a reference for searching whether the magnetic field value of the virtual sensor VL crosses the zero point. Next, the virtual sensor VL closest to the magnetic sensor MS indicating the maximum value is specified, and the magnetic field value of the specified virtual sensor VL and the magnetic field values of the virtual sensors before and after the specified virtual sensor VL cross zero. It is determined whether or not.

  For example, when the magnetic sensor MS5 takes the maximum value, the virtual sensor VL closest to the magnetic sensor MS5 is the virtual sensor VL8, and therefore the polarity of the magnetic field value of the virtual sensor VL8 and the virtual sensor adjacent to the virtual sensor VL8. The polarities of the magnetic field values of VL7 and virtual sensor VL9 are respectively compared. If the polarities of the magnetic field values of the two virtual sensors VL are reversed, the magnetic field value crosses zero between the two virtual sensors, and the first magnet 10A is between the two virtual sensors. There will be.

  If the magnetic field value of the virtual sensor VL7 is positive, the magnetic field value of the virtual sensor VL8 is negative, and the magnetic field value of the virtual sensor VL9 is negative, the magnetic field values of the virtual sensor VL7 and VL8 are opposite in polarity. Therefore, it turns out that there exists the 1st magnet 10A in the meantime. In this embodiment, since the position of the virtual sensor VL7 is at a position of 25 mm when the position of the magnetic sensor MS2 is 0, it can be seen that the first magnet 10A is between 25 mm and 30 mm. Then, in order to obtain the position of the first magnet 10A, the magnetic field values of the two virtual sensors VL straddling zero are linearly interpolated, and the position where the magnetic field value becomes zero is calculated as the position of the first magnet 10A. .

  The linear interpolation method is the same as that in the first embodiment. As described with reference to FIG. 8, the position X of the magnet is obtained by X = X0 + Y0 × (X1−X0) / (Y0−Y1) (formula 1). For example, when X0 = 25, X1 = 30, Y0 = 100, and Y1 = −200, applying to this equation 1, the position of the magnet is 26.667, and the position of the magnet can be easily obtained.

  As described above, in the fifth embodiment, the method for detecting the position of the first magnet 10A in the case 1 where only the first magnet 10A is positioned within the effective detection length A ′ of the magnetic sensor unit 100 has been described. However, in the case 3 where only the second magnet 10B is positioned within the effective detection length A ′ of the magnetic sensor unit 100, the method of detecting the position of the second magnet 10B is also a characteristic of the detection value of the magnetic sensor MS. Is the same as Case 1 except that becomes positive and negative. Therefore, the description thereof is omitted. In the case 2 where the first magnet 10A and the second magnet 10B are within the effective detection length A ′, the position of one of the magnets is preferentially detected as in the first embodiment. do it.

  Since the characteristic of the second group of virtual sensors VL added in the present embodiment also obtains the difference between the detection values of the magnetic sensor MS, the present embodiment is similar to the first embodiment in the external magnetic field such as geomagnetism. Even when the offset component of the magnetic field changes due to the influence of the above, or when the offset component similarly changes due to the temperature characteristics of the magnetic sensor or the like, highly accurate position detection is possible without being affected by these. In this embodiment, the effective detection length A ′ can be 90 mm longer than the effective detection length A 80 mm of the first embodiment without increasing the number of magnetic sensors, and more accurate position detection can be performed. Is possible. The fifth embodiment can be applied to the first to fourth embodiments.

  The embodiment of the present invention has been described above. In these embodiments, in order to discriminate a plurality of magnets, a reference magnet is determined, and the position of each magnet with respect to the reference magnet is stored in advance in the memory of the position detection device as a distance between the magnets. For example, the position (distance) of the magnet located at the rightmost end can be output from the position of the magnet. In either case of using the magnetization direction or the magnetization intensity in order to obtain the reference magnet, the magnetic sensor MS outputs a maximum detection value when the magnet is closest to the magnet. It is necessary to arrange a magnetic sensor. Further, when the magnet position is obtained, linear interpolation of the magnetic field value of the virtual sensor VL is used, but the magnet position may be obtained by curve interpolation. Further, either side of the magnet array or the magnetic sensor may be arranged on the movable side.

1 ... position _{detector, 10A, 10A 1, 10A m} ... first magnet, 10B, the 10B _54, 10B _m ... second magnet, 10C, 10C _m ... third magnet, 10D, the 10D _m ... 4 Magnets, 10E... 5th magnet, 10I _m ... 9th magnet, 10J _m ... 10th magnet, 10K _m , 10K _m−1 ... 11th magnet, 10Re1, 10Re100, 10Re2, 10Rem. ... Multiplexer, 30 ... A / D converter, 40 ... microcomputer, 41 ... virtual sensor magnetic field value generation unit, 42 ... position signal generation unit, 43 ... magnet specifying unit, 44 ... reference magnet discrimination unit, 45 ... reference magnet position calculation , 46 ... multiplexer signal generator, 47 ... magnet movement signal generator, 50 ... output circuit, 60 ... magnet movement mechanism, 100 ... magnetic sensor unit, BS ... substrate, MS ... magnetic sensor, VL ... virtual sensor

Claims (10)

Three or more permanent magnets arranged at a predetermined distance;
M magnets (M is an integer of 3 or more) arranged along the relative movement direction of the plurality of permanent magnets and arranged in a direction to output the maximum detection value when the permanent magnets are closest to each other. A magnetic sensor unit having a sensor;
A difference value between the detection values of the two skipped magnetic sensors is calculated, and (M-2) first magnetic fields of the virtual sensor located between the two skipped magnetic sensors are calculated. A virtual sensor magnetic field value generation unit for generating a magnetic field value of a group of virtual sensors;
From the detection values of the plurality of magnetic sensors, a magnet specifying unit that specifies the permanent magnets facing the magnetic sensors;
A position signal generation unit that outputs a position where the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field value of the virtual sensor with a straight line or a curve becomes zero as the position of the permanent magnet specified by the magnet specifying unit;
A reference magnet discriminating unit for discriminating a reference magnet from the plurality of permanent magnets;
A magnet moving mechanism that relatively moves a plurality of the permanent magnets until the reference magnet determination unit identifies at least one reference magnet;
A reference magnet position calculation unit that calculates the position of at least one reference magnet based on the output of the position signal generation unit;
A position detection device, wherein a distance between the plurality of permanent magnets is set shorter than an effective detection length of the magnetic sensor unit. The virtual sensor magnetic field value generation unit further calculates a difference value between the detection values of the adjacent magnetic sensors, and calculates the difference value between the two adjacent magnetic sensors. And (M-1) magnetic field values of the second group of virtual sensors are calculated,
The position signal generation unit has a magnetic field value of a magnetic field distribution obtained by interpolating a magnetic field value of the virtual sensor including the first group of virtual sensors and the second group of virtual sensors with a straight line or a curve becomes zero. The position detection device according to claim 1, wherein the position is output as a position of the permanent magnet specified by the magnet specifying unit.   The position signal generation unit specifies the magnetic sensor that outputs the maximum detection value among the magnetic sensors, and the magnetic field value of the virtual sensor closest to the magnetic sensor and the virtual sensors before and after the virtual sensor It is determined whether or not the magnetic field value of the permanent magnet crosses zero, the magnetic field values of the two virtual sensors straddling zero are interpolated with a straight line or a curve, and the position where the magnetic field value becomes zero is the position of the permanent magnet The position detection device according to claim 1 or 2, wherein   4. The position detection device according to claim 1, wherein the reference magnet is the permanent magnet having a magnetization direction different from that of the other permanent magnet with respect to the moving direction. 5.   4. The position detection device according to claim 1, wherein the reference magnet is the permanent magnet having a different magnetization strength from the other permanent magnets. 5.   4. The position detection device according to claim 1, wherein the reference magnet is the permanent magnet positioned at both ends of the plurality of permanent magnets. 5.   The position detection device according to any one of claims 1 to 3, wherein all the distances between adjacent permanent magnets are different.   The plurality of permanent magnets constitute one magnet set, the plurality of magnet sets are arranged along the moving direction, and the permanent magnets arranged at one end are respectively configured as the reference magnets, The position detection device according to any one of claims 1 to 3, wherein a combination of distances between the reference magnet and the permanent magnets on both sides adjacent to the reference magnet is different depending on each of the reference magnets. .   The position detection device according to claim 8, wherein the plurality of permanent magnets other than the reference magnet belonging to each magnet set have different inter-magnet distances.   The position detection device according to claim 1, wherein the magnetic sensors of the magnetic sensor unit are arranged at an equal pitch.

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