JP2019144086A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen an effective detection length without being affected by a change in an offset component due to geomagnetism, temperature characteristics of a magnetic sensor, or the like, and without increasing the number of magnetic sensors. SOLUTION: A position detection device 1 has a plurality of magnets 10A and 10B arranged at a predetermined distance, and M magnets (M) arranged in a direction to output a maximum detection value when the magnets are closest to each other. Calculate the difference between the detected values of the magnetic sensor MS (an integer of 3 or more) and the two magnetic sensors that skip one, and the magnetic field value of the virtual sensor located between the two magnetic sensors that skip one. As a result, a virtual sensor magnetic field value generation unit 41 that generates magnetic field values of (M-2) virtual sensors, and a magnet identification unit 43 that identifies a magnet facing the magnetic sensor from the detection values of a plurality of magnetic sensors. A position signal generation unit 42 is provided which 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 identification unit 43. [Selection diagram] Fig. 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, in Patent Document 1, a plurality of magnetic sensors are arranged on a straight line, and a point where the magnetic field value becomes zero is obtained from a magnetic field distribution obtained by interpolating a 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 is disclosed.

  However, this method 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 detection range of the magnet is limited to the distance between the magnetic sensors at both ends of the plurality of magnetic sensors arranged, and there is a problem that the effective detection length is short.

JP-A-8-50004

  As described above, the conventional detection device has a problem in that when the magnetic field of the magnet is detected, an error occurs in the position detection value due to the influence of an external magnetic field such as geomagnetism or the effective detection length is short.

  The present invention has been made in view of these circumstances, and even when the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism or when the offset component changes similarly due to the temperature characteristics of the magnetic sensor or the like. An object of the present invention is to provide a position detection device that is not affected by an offset component and that can increase the effective detection length without increasing the number of magnetic sensors.

  In order to solve the above-described problem, the first technical means of the present invention includes a plurality of permanent magnets arranged at a predetermined distance and a plurality of permanent magnets arranged along a relative moving direction of the permanent magnets, Difference value between detection values of M magnetic sensors (M is an integer of 3 or more) arranged in a direction to output the maximum detection value when the permanent magnets are closest to each other and one magnetic sensor that is skipped by one And (M−2) virtual sensor magnetic field value generation that generates magnetic field values of the first group of virtual sensors as the magnetic field value of the virtual sensor located in the middle of the two skipped magnetic sensors. A magnetic field distribution value obtained by interpolating a magnetic field value of the virtual sensor, a magnet specifying unit that specifies the permanent magnet facing the magnetic sensor from detection values of the plurality of magnetic sensors, and zero The permanent position specified by the magnet specifying unit. A position signal generating unit for outputting as a position of the magnet, is characterized in that it comprises a.

  According to a second technical means, in the first technical means, the virtual sensor magnetic field value generation unit further calculates a difference value of each detection value of the adjacent magnetic sensor, 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 outputting the position at which the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field values of the virtual sensors including the second group of virtual sensors becomes zero as the position of the permanent magnet specified by the magnet specifying unit. It is a feature.

  According to a third technical means, in the first or second technical means, the magnet specifying unit faces the magnetic sensor from among the plurality of permanent magnets based on a polarity of a detection value of the magnetic sensor. A permanent magnet is specified.

  According to a fourth technical means, in any one of the first to third technical means, the magnet specifying unit is configured to select the magnetism from a plurality of the permanent magnets based on a magnitude of a detection value of the magnetic sensor. The permanent magnet facing the sensor is specified.

  According to a fifth technical means, in the first or second technical means, the magnet specifying unit is arranged such that a distance between the magnets is shorter than 1 / n (n is an integer of 2 or more) of an effective detection length of the magnetic sensor. And identifying the permanent magnet facing the magnetic sensor from among the plurality of permanent magnets based on detection values of n permanent magnets magnetized in the same magnetization direction with respect to the moving direction. It is what.

  A sixth technical means is the first technical means according to any one of the first to third technical means, wherein the magnet specifying unit is configured such that a distance between magnets is 1 / (n−1) (n is 2) of an effective detection length of the magnetic sensor. Based on the detection values of n permanent magnets arranged shorter than the above integer) and magnetized alternately in different directions with respect to the moving direction, the magnetic sensor is opposed to the magnetic sensor from among the plurality of permanent magnets. The permanent magnet is specified.

  A seventh technical means is any one of the first to sixth technical means, wherein the position signal generation unit specifies the magnetic sensor that outputs the maximum detected value of the magnetic sensors, and It is determined whether or not the magnetic field value of the virtual sensor closest to the sensor and the magnetic field values of the virtual sensor before and after the virtual sensor cross zero, and the magnetic field values of the two virtual sensors straddling zero And a position where the magnetic field value becomes zero is output as the position of the permanent magnet.

  According to an eighth technical means, in any one of the first to seventh technical means, the position signal generation unit calculates a position of the first permanent magnet facing the magnetic sensor, and calculates the calculated first The position of the second permanent magnet is output by adding the distance between the first permanent magnet and the second permanent magnet not facing the magnetic sensor to the position of the permanent magnet. It is characterized by this.

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

  A tenth technical means according to any one of the first to ninth technical means, wherein the plurality of permanent signals calculated by the position signal generation unit when the plurality of permanent magnets are opposed to the magnetic sensor. The apparatus further includes an inter-magnet distance calculation unit that calculates the distance between the plurality of permanent magnets based on the position of the magnet.

  According to the present invention, even when the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism or when the offset component changes similarly due to the temperature characteristics of the magnetic sensor, etc., it is not affected by the offset component. Furthermore, the detection accuracy can be improved and the effective detection length can be increased without increasing the number of magnetic sensors. If the effective range is the same as the conventional one, the detection device can be downsized.

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 the relationship of the specific arrangement | positioning of a magnet and a magnetic sensor. 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 a 1st magnet. It is a figure for demonstrating the characteristic of the difference value of each detection value of two magnetic sensors skipped when the 1st magnet 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 in the position detection apparatus which concerns on embodiment of this invention. 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 a 2nd magnet. It is a figure for demonstrating the characteristic of the difference value of each detection value of two skipped magnetic sensors when a 2nd magnet opposes a magnetic sensor. It is a figure which shows the case where only a 1st magnet is located within the effective detection length of a magnetic sensor. It is a figure which shows the case where a 1st magnet and a 2nd magnet are located within the effective detection length of a magnetic sensor. It is a figure which shows the case where only a 2nd magnet is located within the effective detection length of a magnetic sensor. It is a figure for demonstrating the characteristic of the difference value of each detection value of two adjacent magnetic sensors when a 1st magnet opposes a 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. It is a figure which shows the example of the calculation flow of the distance between magnets. It is a figure which shows the other structure of the position detection apparatus which concerns on embodiment of this invention. It is a figure which shows the further another structure of the position detection apparatus which concerns on embodiment of this invention. In the position detection apparatus shown in FIG. 18, it is a figure for demonstrating the case where a magnet position differs.

  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 apparatus according to the first embodiment of the present invention. In the present embodiment, an example in which two magnets of a first magnet 10A and a second magnet 10B having different magnetization directions with respect to the moving direction are used as the plurality of magnets will be described.

  The position detection apparatus 1 includes a first magnet 10A and a second magnet 10B for detection, a plurality of magnetic sensors MS that detect the first magnet 10A and the second magnet 10B, and a plurality of magnetic sensors MS. A multiplexer 20 for switching, an A / D converter 30 for converting an analog signal from the magnetic sensor MS into a digital signal, and a microcomputer for calculating the positions of the first magnet 10A and the second magnet 10B based on the detection value of the magnetic sensor MS 40, an output circuit 50 for outputting the value calculated by the microcomputer 40 as an analog signal. 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 a virtual sensor magnetic field value generation unit 41, a position signal generation unit 42, a magnet identification unit 43, an intermagnet distance calculation unit 44, and a multiplexer signal generation unit 45 as functional units. 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 showing a specific arrangement relationship between the magnet and the magnetic sensor, and FIG. 3 is a diagram when the relative positions of the magnet and the magnetic sensor are changed. In this embodiment, M, for example, 11 magnetic sensors MS are arranged on a straight line on the substrate BS at a pitch P of 10 mm, and are connected to the multiplexer 20. The first magnet 10A and the second magnet 10B are fixed to a moving mechanism (not shown) by a distance L between the magnets, and both move parallel to the substrate BS while maintaining a certain distance from the magnetic sensors MS1 to MS11. To do. The magnetization direction of the first magnet 10A is magnetized in the S and N poles with respect to the moving direction, and the magnetization direction of the second magnet 10B is N with respect to the moving direction, as opposed to the first magnet 10A. It is magnetized to the pole and the S pole. The directions of magnetization may be opposite to each other. The magnetic sensor MS detects the horizontal magnetic fields of the first magnet 10A and the second magnet 10B. 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 MS 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 L between the first magnet 10A and the second magnet 10B is set to a distance shorter than the effective detection length A of the magnetic sensor MS, and is set to 70 mm, for example, in this embodiment. Yes. FIG. 2 shows the case where the first magnet 10A faces the magnetic sensor MS2, and FIG. 3 shows the case where the second magnet 10B faces the magnetic sensor MS10. 1 is a range from the position where the first magnet 10A faces the magnetic sensor MS2 to the position where the second magnet 10B faces the magnetic sensor MS10. The position of the magnet 10B can be detected. Accordingly, the total effective detection length of the position detection device 1 is 150 mm, which is obtained by adding the inter-magnet distance L (70 mm) to the effective detection length A (80 mm) of the magnetic sensor MS.

First, a method for detecting the position of the first magnet 10A when the first magnet 10A is within the range of the effective detection length A of the magnetic sensor MS will be described.
FIG. 4 is a diagram for explaining characteristics of a magnetic field value that is a detection value of the magnetic sensor with respect to the first magnet. The characteristics shown in FIG. 4 use a saturable coil for the magnetic sensor MS and neodymium φ5 × 6 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. It is in. FIG. 4 also shows 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 MS, 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 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.

  In the multiplexer 20, the magnetic sensors MS <b> 1 to MS <b> 11 are sequentially switched in response to a command from the multiplexer signal generation unit 45 of the microcomputer 40, and analog signals from each magnetic sensor MS are converted into digital signals by the A / D converter 30 and input to the microcomputer 40. .

  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 characteristics of the difference value between the detection values of two skipped magnetic sensors when the first magnet faces the magnetic sensor. FIG. It is a figure which shows the relationship between a position 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 difference between the detection values of the magnetic sensor MS is obtained, even when the offset component of the magnetic field changes due to the influence of an external magnetic field such as geomagnetism, the detection position of the first magnet 10A is obtained. Not affected. 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.

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 showing an example of a processing flow in the position detection apparatus according to the embodiment of the present invention.
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 generation unit 45, 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, and the position where the magnetic field value becomes zero is the position of the first magnet 10A. Calculate as

  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 magnet position. 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 MS has been described above. Next, the second magnet 10B is a magnetic sensor. A method for detecting the position of the second magnet 10B when the effective detection length A is within the range of the MS 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 the second magnet, and the second magnet 10B uses neodymium φ5 × 6 similarly to the first magnet 10A. doing.

  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. Therefore, it is possible to distinguish between the first magnet 10A and the second magnet 10B, and the magnet specifying unit 43 specifies the magnet using this characteristic.

  FIG. 10 is a diagram for explaining the characteristic of the difference value between the detection values of two skipped magnetic sensors when the second magnet faces 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.

  Next, in this embodiment, there are a plurality of magnets, and the distance L between the magnets is set to be shorter than the effective detection length A of the magnetic sensor MS. Therefore, when only the first magnet 10A is positioned within the effective detection length A of the magnetic sensor MS, only when the second magnet 10B is positioned, or both the first magnet 10A and the second magnet 10B are positioned. It is necessary to divide the processing in three ways.

  FIG. 11 is a diagram illustrating a case where only the first magnet is positioned within the effective detection length of the magnetic sensor, and FIG. 12 illustrates that the first magnet and the second magnet are within the effective detection length of the magnetic sensor. FIG. 13 is a diagram illustrating a case where only the second magnet is positioned within the effective detection length of the magnetic sensor.

  As shown in FIG. 11, when only the first magnet 10A is positioned within the effective detection length A of the magnetic sensor MS (hereinafter referred to as “case 1”), the position of the first magnet 10A is obtained to detect the position. The output value of the device 1 is assumed. In addition, as shown in FIG. 12, when both the first magnet 10A and the second magnet 10B are located within the effective detection length A of the magnetic sensor MS (hereinafter referred to as “case 2”), the first in advance. It is determined which of the magnet 10A and the second magnet 10B is prioritized. For example, when giving priority to the first magnet 10 </ b> A, as in the case 1, the position of the first magnet 10 </ b> A is obtained and used as the output value of the position detection device 1. As shown in FIG. 13, when only the second magnet 10B is positioned within the effective detection length A of the magnetic sensor MS (hereinafter referred to as “case 3”), the position of the second magnet 10B is obtained, and further 70 mm, which is the distance L between magnets, is added to the value to obtain the output value of the position detection device 1. In addition, when giving priority to the 2nd magnet 10B in a 2nd case, the method similar to case 3 is taken.

  Adding 70 mm, which is the distance L between the magnets, to the position of the second magnet 10B means that the first magnet 10A is outside the effective detection length A of the magnetic sensor MS, but the second magnet 10B. The position of the first magnet 10A is obtained from the position of. Thereby, compared with the case where one magnet is used, the total effective detection length of the position detection device is increased by the distance L between the magnets and is increased to 150 mm, and the first magnet 10A and the second magnet 10B are switched. Even in this case, continuous position detection is possible. If this method is used, when the total effective detection length is the same as the conventional one, it is possible to reduce the number of parts such as the magnetic sensor MS and the substrate BS and to reduce the size of the apparatus.

  Next, in the present embodiment, a method for reliably detecting cases 1 to 3 and preventing erroneous detection will be described. First, when detecting the first magnet 10A, the magnetic sensor MS that outputs the maximum value on the plus side is searched for from the detection values of the magnetic sensors MS. At this time, the value on the plus side of the second magnet 10B is not detected. As shown in FIG. 9, from the characteristic of the detection value of the magnetic sensor MS for the second magnet 10B, there is a maximum negative value at the position of 0 mm, but it also has a maximum value on the positive side near ± 20 mm. The second magnet 10B generates a detected value on the plus side in the magnetic sensor MS.

  If the value on the plus side of the second magnet 10B is erroneously detected, the first magnet 10A is also within the range of the effective detection length A even in the case where only the second magnet 10B is not actually there but the first magnet 10A. It is judged that there is, and the normal position cannot be detected. For this reason, the value on the plus side of the second magnet 10B is not erroneously detected. Specifically, the maximum value on the plus side of the second magnet 10B is sufficiently smaller than the maximum value on the plus side of the first magnet 10A, so that the value on the plus side of the second magnet 10B is not erroneously detected. A threshold is provided for the detected value. For example, by not detecting a positive value with a magnetic field value of 100 or less as the detection value threshold value, the positive value of the second magnet 10B is not erroneously detected.

  Similarly, when detecting the second magnet 10B, a negative value generated by the first magnet 10A is not erroneously detected. For example, by providing a threshold value for the magnetic field value −100 and not detecting a negative value that is equal to or greater than the threshold value, the negative value of the first magnet 10A is not erroneously detected.

  Thereby, the magnet specific | specification part 43 can discriminate | determine reliably it is in any state of case 1 to 3. For example, when only the maximum value on the plus side is detected, it is determined that the case 1 has only the first magnet 10A, and when only the maximum value on the minus side is detected, the case 3 has only the second magnet 10B. If the maximum value on both the positive side and the negative side is detected, it is determined that Case 2 has both the first magnet 10A and the second magnet 10B.

  Thus, in the present embodiment, it is possible to detect the position of the first magnet 10A and the position of the second magnet 10B continuously from case 1 to case 3. The position detection device 1 discriminates between the first magnet 10A and the second magnet 10B. In the case 3, as shown in FIG. 3 or 13, the position of the magnetic sensor MS is determined from the position of the second magnet 10B. It becomes possible to detect the position of the first magnet 10A outside the range of the effective detection length A. Further, from a different perspective, in case 1, as shown in FIG. 2 or 11, the position of the second magnet 10B that is outside the range of the effective detection length A of the magnetic sensor MS from the position of the first magnet 10A. It becomes possible to detect. As described above, in the present invention, the total effective detection length as the position detection device is increased by the distance L between the magnets.

(Second 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 second embodiment, it is possible to detect the position of the magnet with higher accuracy even by linear interpolation with simple calculation. For this reason, in the second 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 value 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, a method for detecting the position of the first magnet 10A will be described in the case 1 where only the first magnet 10A is positioned within the effective detection length A of the magnetic sensor MS shown in FIG.
FIG. 14 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. 15 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. 14, 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. 14 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 in FIG. 11 by 10 mm in the minus direction of the substrate BS, and the characteristic of the virtual sensor VL5 is the virtual sensor VL3 in FIG. The characteristic is shifted by 10 mm in the plus direction of the substrate BS.

  Accordingly, in the second embodiment, nine even-numbered first group virtual sensors VL having the same characteristics as those shown in FIG. 5 and 10 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 second embodiment, the effective detection length of the magnetic sensor MS is between virtual sensors positioned at both ends along the arrangement direction of the magnetic sensor MS. It can be defined as equivalent to distance.

In the second embodiment, the method of 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 magnetic sensors MS 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 second 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 MS has been described. In the case 3 where only the second magnet 10B is positioned within the effective detection length A ′ of the magnetic sensor MS, the method of detecting the position of the second magnet 10B also has positive / negative characteristics of the detection value of the magnetic sensor MS. It is the same as Case 1 only in reverse. 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 the present embodiment, highly accurate position detection is possible even by linear interpolation without increasing the number of magnetic sensors. Further, the effective detection length A ′ is 90 mm, which is more than the effective detection length A of 80 mm in the first embodiment. Can also be long.

(Third embodiment)
In the first embodiment and the second embodiment, as shown in FIG. 13, when only the second magnet 10B is within the range of the effective detection length A of the magnetic sensor MS, the second magnet 10B is positioned at the position of the second magnet 10B. The position of the first magnet 10A is output by adding the distance L between the magnets of 70 mm. However, since the distance between the magnets of 70 mm is a fixed value that does not consider the installation error or the like, if the distance between the magnets L is shifted due to the installation error or the like, an error occurs in the output of the position detection device 1.

  The third embodiment has a function of calculating and correcting the distance L between magnets. In the present embodiment, as shown in FIG. 12, when both the first magnet 10A and the second magnet 10B are within the effective detection length A of the magnetic sensor MS, the distance between the magnets shown in FIG. The calculation unit 44 causes the position signal generation unit 42 to calculate the positions of both the first magnet 10A and the second magnet 10B, and obtains the inter-magnet distance L from the calculated position. Then, when only the second magnet 10B is positioned within the effective detection length A, the first magnet 10B is added to the position of the second magnet 10B by adding the inter-magnet distance L calculated by the inter-magnet distance calculator 44. The position of the magnet 10A is output.

  The value of the inter-magnet distance L can be input in advance to the memory of the microcomputer 40. However, if the actual input value differs from the calculated value of the inter-magnet distance by the inter-magnet distance calculation unit 44, the value is input in advance. The input value is corrected with the calculated value of the inter-magnet distance calculating unit 44. This enables highly accurate position detection.

Next, a calculation method of the inter-magnet distance L in the case of the first embodiment will be described, but the calculation method of the inter-magnet distance L in the case of the second embodiment is the same.
FIG. 16 is a diagram illustrating an example of a calculation flow of the distance between magnets. First, the magnet specifying unit 43 determines whether or not both the first magnet 10A and the second magnet 10B are within the effective detection length A of the magnetic sensor MS (step S11). If both magnets are not within the range of the effective detection length A, move the magnets and wait until both magnets are within the range of the effective detection length A.

  If both magnets are within the range of the effective detection length A, first, the position signal generator 42 obtains the position of the first magnet 10A (step S12). The position of the first magnet 10A is detected by specifying the magnetic sensor MS that outputs the maximum detected value on the plus side, and checking whether the magnetic field values of the two virtual sensors VL close to the magnetic sensor MS cross zero. The position of the first magnet 10A is obtained by searching and linearly interpolating the magnetic field values of the two virtual sensors whose magnetic field values cross zero.

  When the distance L between the first magnet 10A and the second magnet 10B is 70 mm, both the first magnet 10A and the second magnet 10B are within the range of the effective detection length A of the magnetic sensor MS. Therefore, the first magnet 10A comes near the magnetic sensors MS9 and MS10. For example, when the magnetic sensor MS9 takes the maximum value on the positive side of the detection value, the position is the position of the virtual sensor VL8, and the polarities of the magnetic field values of the virtual sensor VL8 and the virtual sensors VL7 and VL9 before and after are compared. . If the magnetic field value of the virtual sensor VL7 is positive, the magnetic field value of the virtual sensor VL8 is positive, and the magnetic field value of the virtual sensor VL9 is negative, the polarities of the magnetic field values of the virtual sensor VL8 and the virtual sensor VL9 are opposite. Thus, the first magnet 10A is present, and linear interpolation is performed using the magnetic field values of the virtual sensor VL8 and the virtual sensor VL9.

  By linear interpolation, the position X of the first magnet 10A can be obtained by Expression 1: X = X0 + Y0 × (X1−X0) / (Y0−Y1)). In this embodiment, since the interval between the virtual sensors VL is 10 mm, it can be seen that the position (X0) of the virtual sensor VL8 is 70 mm from the virtual sensor VL1, and the position (X1) of the virtual sensor VL9 is 80 mm. For example, when the magnetic field value (YO) of the virtual sensor VL8 is 100 and the magnetic field value (Y1) of the virtual sensor VL9 is −200, the position X of the first magnet 10A is obtained as 73.333 mm from Equation 1.

  Next, the position of the second magnet 10B is obtained (step S13). In the flow shown in FIG. 16, the order of step S12 and step S13 may be interchanged. The position of the second magnet 10B is detected by specifying the magnetic sensor MS that outputs the maximum negative detection value, and checking whether the magnetic field values of the two virtual sensors VL close to the magnetic sensor MS cross zero. The position of the second magnet 10B is obtained by searching and linearly interpolating the magnetic field values of the two virtual sensors whose magnetic field values cross zero.

  Since the distance L between the first magnet 10A and the second magnet 10B is 70 mm, when both magnets are within the effective detection length A, the second magnet 10B is near the magnetic sensors MS2 and MS3. I come to. For example, when the detection value of the magnetic sensor MS2 takes the maximum value on the minus side, the position is the position of the virtual sensor VL1, and linear interpolation is performed between the magnetic field values of the virtual sensor VL1 and the virtual sensor VL2.

  By linear interpolation, the position X of the second magnet 10B is obtained by the equation 1: X = X0 + Y0 × (X1-X0) / (Y0-Y1). The position (X0) of the virtual sensor VL1 is 0 mm and the position (X1) of the virtual sensor VL2 is 10 mm. For example, the magnetic field value (YO) of the virtual sensor VL1 is −250, and the magnetic field value (Y1) of the virtual sensor VL9 is 250. In this case, the position of the second magnet 10B is obtained as 5.000 mm from Equation 1.

  When the respective positions of the first magnet 10A and the second magnet 10B are obtained, the process proceeds to step S14, and the inter-magnet distance calculation unit 44 changes the inter-magnet distance L from the position of the first magnet 10A to the second. It is obtained by subtracting the position of the magnet 10B. In the case of this example, since the position of the first magnet 10A is 73.333 mm and the position of the second magnet 10B is 5.000 mm, 73.333-55.00 = 68.333, and the inter-magnet distance L Is 68.333 mm.

  If there is an installation error in the inter-magnet distance L, for example, if the inter-magnet distance L is set to 70 mm and a fixed value in the first embodiment, the positions of the first magnet 10A and the second magnet 10B are set. When the detected value is switched, an error occurs in the output of the position detection device 1 by the difference from the actual distance between the magnets. However, in the present embodiment, when both the first magnet 10A and the second magnet 10B are within the range of the effective detection length A of the magnetic sensor MS, the actual inter-magnet distance L from the position of each magnet. Can be obtained. Therefore, in the present embodiment, when only the second magnet 10B is within the range of the effective detection length A, that is, in the case 3, the inter-magnet distance calculation unit 44 calculates the position of the second magnet 10B. The actual value of the distance L between the magnets is added to obtain the position of the first magnet 10A, thereby preventing an error.

(Fourth embodiment)
In the first to third embodiments, the case of two magnets having different magnetization directions with respect to the movement direction has been described as an example in order to discriminate a plurality of magnets, but the magnetization directions may be the same. FIG. 17 is a diagram showing another configuration of the position detection device according to the embodiment of the present invention, and shows a case where n = 2 when the number of magnets is n (n is an integer of 2 or more).

  In the present embodiment, the position detection device includes a first magnet 10A and a second magnet 10B that are arranged in the same direction as the moving direction, and the first magnet 10A and the second magnet 10B. M, for example, 11 are arranged in a straight line on the substrate BS at a pitch P of 10 mm. The configurations of the magnetic sensor MS and the substrate BS are the same as those in the first embodiment, and the effective detection length A is 80 mm. Then, the two magnets of the first magnet 10A and the second magnet 10B are arranged, for example, at an interval of 30 mm so that the distance L between the magnets is shorter than A / 2. This magnet arrangement is for identifying each magnet and detecting its absolute position even when a plurality of magnets having the same magnetization direction with respect to the moving direction are used.

  17A shows the case where only the first magnet 10A is located within the effective detection length A of the magnetic sensor MS, and FIG. 17B shows the first detection within the effective detection length A of the magnetic sensor MS. When the magnet 10A and the second magnet 10B are located, FIG. 17C shows a case where only the second magnet 10B is located within the effective detection length A of the magnetic sensor MS.

  Based on the detection value from the magnetic sensor MS, the magnet specifying unit 43, as shown in FIG. 17 (A), in the case where the detected position is one and the detection position is less than the effective detection length A / 2. Then, the detected magnet is identified as the first magnet 10A, and the position signal generator 42 uses the position of the first magnet 10A as the output value of the position detection device 1. As shown in FIG. 17B, when two magnets are detected, the magnet specifying unit 43 includes the first magnet 10A on the magnetic sensor MS11 side and the second magnet 10B on the magnetic sensor MS1 side. For example, the position signal generation unit 42 gives priority to the position of the first magnet 10 </ b> A and sets the position of the first magnet 10 </ b> A as the output value of the position detection device 1. Furthermore, as shown in FIG. 17C, when the detected magnet is one and the detected position is a position longer than the effective detection length A / 2, the magnet specifying unit 43 determines that the detected magnet is the second magnet. The position signal generator 42 identifies the magnet 10B and outputs a value obtained by adding the inter-magnet distance L to the position of the second magnet 10B as the position of the first magnet 10A. Therefore, in this embodiment, the total effective detection length of the position detection device is 110 mm, which is a length A + L obtained by adding the distance L between magnets to the effective detection length A of the magnetic sensor MS.

Although the case where there are two magnets has been described above, the number n of magnets having the same magnetization direction with respect to the moving direction may be three or more. For example, when n = 3 magnets, these three magnets are arranged such that the distance L _sub between the magnets is shorter than 1 / n of the effective detection length A of the magnetic sensor MS, that is, 1/3. When the three magnets are the first magnet, the second magnet, and the third magnet from the side close to the magnetic sensor MS11, the positional relationship of the magnets facing the magnetic sensor MS is the following five types, In the case, the magnet specifying unit 43 can specify the magnet facing the magnetic sensor MS based on the detection value from the magnetic sensor MS.

(Case 1 ′) When the number of detected magnets is one and the detection position is less than the effective detection length A / n, that is, the position less than A / 3, the position of the first magnet can be specified.
(Case 2 ′) When there are two detected magnets and the detection position of one of the magnets is less than the effective detection length A / n, that is, less than A / 3, the first magnet and the second magnet The position can be specified.
(Case 3 ′) When the number of detected magnets is three, the positions of all the magnets can be specified.
(Case 4 ') If the number of detected magnets is two and the detection position of one of the magnets is greater than or equal to the effective detection length (AA / n), that is, 2 × A / 3 or more, the second magnet And the position of the third magnet can be specified.
(Case 5 ') When the number of detected magnets is one and the detected position is at or above the effective detection length (AA / n), that is, at a position of 2 × A / 3 or more, the position of the third magnet is Can be identified.

  And the position signal generation part 42 can output the position of the magnet which is not facing the magnetic sensor MS from the position of the magnet which the magnet specific | specification part 43 specified, and the distance L between magnets. The total effective detection length as the position detection device is a length A + L obtained by adding the distance L between the magnets located at both ends to the effective detection length A of the magnetic sensor MS. When the present embodiment and the second embodiment are combined, the total effective detection length as the position detection device is the length A ′ + L.

(Fifth embodiment)
In the first to third embodiments, the case of two magnets having different magnetization directions with respect to the moving direction has been described as an example in order to discriminate a plurality of magnets. However, the number n of magnets is more than two. Also good. 18 is a diagram showing another configuration of the position detection device according to the embodiment of the present invention, and FIG. 19 is a diagram for explaining a case where the magnet positions are different in the position detection device shown in FIG. . In the present embodiment, the case where n = 3 is shown as the number of magnets n (n is an integer of 2 or more).

  In the present embodiment, the position detection device includes a first magnet 10A, a second magnet 10B, and a third magnet 10C that are arranged in directions in which the magnetization directions are alternately different from the moving direction, and the first magnets. As a plurality of magnetic sensors MS that detect the magnet 10A, the second magnet 10B, and the third magnet 10C, M, for example, 11 are arranged on the substrate BS at a pitch P of 10 mm intervals on a straight line. The configurations of the magnetic sensor MS and the substrate BS are the same as those in the first embodiment, and the effective detection length A is 80 mm.

  The two magnets, the first magnet 10A and the second magnet 10B, have an interval of, for example, 30 mm so that the distance L1 between the magnets is shorter than A / (n−1), that is, A / 2. It is arranged in the space. Similarly, the two magnets of the second magnet 10B and the third magnet 10C have a distance of 35 mm, for example, so that the distance L2 between the magnets is shorter than A / (n−1), that is, A / 2. It is arranged in the space. This magnet arrangement is for specifying each magnet and detecting its absolute position even when a plurality of magnets having different magnetization directions with respect to the moving direction are used.

  18A shows the case where only the first magnet 10A is located within the effective detection length A of the magnetic sensor MS, and FIG. 18B shows the first detection within the effective detection length A of the magnetic sensor MS. When the magnet 10A and the second magnet 10B are positioned, FIG. 18C shows all of the first magnet 10A, the second magnet 10B, and the third magnet 10C within the effective detection length A of the magnetic sensor MS. 19A shows a case where the second magnet 10B and the third magnet 10C are located within the effective detection length A of the magnetic sensor MS, and FIG. This shows a case where only the third magnet 10C is positioned within the effective detection length A.

  Based on the detection value from the magnetic sensor MS, the magnet specifying unit 43 has one detected magnet and its detection position is less than the effective detection length A / (n−1), as shown in FIG. That is, when the position is less than A / 2, the detected magnet is identified as the first magnet 10A, and the position signal generation unit 42 determines the position of the first magnet 10A as the output value of the position detection device 1. And

  As shown in FIG. 18B, when two magnets are detected, the maximum value detected by the magnetic sensor MS by the first magnet 10A is on the plus side, and the magnetism by the second magnet 10B. The maximum value detected by the sensor MS appears on the minus side. The magnet specifying unit 43 uses this characteristic to specify the first magnet 10A or the second magnet 10B. For example, the position signal generation unit 42 determines the position of the first magnet 10A of the position detection device 1. Output value.

  Next, as shown in FIG. 18C, when all of the first magnet 10A, the second magnet 10B, and the third magnet 10C are located within the effective detection length A of the magnetic sensor MS, Since the number of magnets to be detected is 3, the magnet specifying unit 43 can specify all three magnets. For example, the position signal generation unit 42 sets the position of the first magnet 10 </ b> A as the output value of the position detection device 1.

  Next, as shown in FIG. 19A, when the number of detected magnets is two, the maximum value of the detection value of the magnetic sensor MS by the second magnet 10B is on the minus side, and by the third magnet 10C. The maximum value detected by the magnetic sensor MS appears on the plus side. The magnet specifying unit 43 uses this characteristic to specify the second magnet 10B or the third magnet 10C. For example, the position signal generation unit 42 sets the inter-magnet distance L1 at the position of the second magnet 10B. The added value is output as the position of the first magnet 10A.

  Thus, in this embodiment, when there are two detected magnets, there are two cases shown in FIG. 18B and FIG. 19A, respectively. On the other hand, since the magnets are alternately magnetized to polarities, whether the detected two magnets are the first magnet 10A and the second magnet 10B based on the polarity of the detection value of the magnetic sensor MS or the second magnet. Whether it is 10B and the third magnet 10C can be discriminated. For example, two magnets can be specified by taking the difference between the maximum value on the positive side and the maximum value on the negative side of the detection value of the magnetic sensor MS and determining the polarity of the difference.

  Further, as shown in FIG. 19 (B), when the number of detected magnets is one and the detection position is a position longer than the effective detection length (AA / (n-1)), that is, more than A / 2. In this case, the magnet specifying unit 43 specifies that the detected magnet is the third magnet 10C, and the position signal generating unit 42 adds the inter-magnet distances L1 and L2 to the position of the third magnet 10C. The value is output as the position of the first magnet 10A. Therefore, in this embodiment, the total effective detection length of the position detection device is a length A + L obtained by adding the distance L (= L1 + L2) between the magnets located at both ends to the effective detection length A of the magnetic sensor MS, which is 145 mm. .

  As described above, also in the present embodiment, the position signal generation unit 42 can output the position of the magnet not facing the magnetic sensor MS from the position of the magnet specified by the magnet specifying unit 43 and the distance L between the magnets. it can. As in the first to fourth embodiments, the total effective detection length as the position detection device is a length A + L obtained by adding the distance L between the magnets of the magnets at both ends to the effective detection length A of the magnetic sensor MS. Further, when the present embodiment and the second embodiment are combined, the total effective detection length as the position detection device is the length A ′ + L. Note that the first embodiment corresponds to the case where the number n of magnets is set to two in the fifth embodiment. The number n of magnets may be 4 or more.

  The embodiment of the present invention has been described above. In these embodiments, in order to discriminate a plurality of magnets, the case where the magnetization direction is the same as the case of a plurality of magnets having different magnetization directions with respect to the moving direction has been described as an example. These magnets may be used, and by combining these, the detection range of the position detection device may be further extended. When using a plurality of magnets having different magnetization strengths, it is necessary to use a magnet having a strength that can sufficiently distinguish the difference in the maximum value of the detection values of the magnetic sensor when each magnet is opposed to the magnetic sensor MS. desirable. 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. Thereby, the absolute position of the magnet can be detected, and the position can be detected even when the initial power source of the position detecting device is turned on. 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 substrate on which the magnet and the magnetic sensor are mounted may be arranged on the movable side.

DESCRIPTION OF SYMBOLS 1 ... Position detection apparatus, 10A ... 1st magnet, 10B ... 2nd magnet, 20 ... Multiplexer, 30 ... A / D converter, 40 ... Microcomputer, 41 ... Virtual sensor magnetic field value generation part, 42 ... Position signal generation , 43... Magnet identification unit, 44... Magnet distance calculation unit, 45 .. multiplexer signal generation unit, 50... Output circuit, BS .. substrate, MS .. magnetic sensor, VL.

Claims (10)

A plurality of 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 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 becomes zero, as the position of the permanent magnet specified by the magnet specifying unit;
A position detection device comprising:
The virtual sensor magnetic field value generation unit further calculates a difference value between detection values of the adjacent magnetic sensors, and calculates the magnetic field value of the virtual sensor positioned 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 is configured to determine a position at which a magnetic field value of a magnetic field distribution obtained by interpolating magnetic field values of the virtual sensors including the first group of virtual sensors and the second group of virtual sensors is zero, The position detection device according to claim 1, wherein the position is output as the position of the permanent magnet specified by the magnet specifying unit.
The said magnet specific | specification part specifies the said permanent magnet which opposes the said magnetic sensor from the said several permanent magnets based on the polarity of the detected value of the said magnetic sensor. Position detector.
The said magnet specific | specification part specifies the said permanent magnet which opposes the said magnetic sensor from the said several permanent magnets based on the magnitude | size of the detected value of the said magnetic sensor, The Claim 1 to 3 characterized by the above-mentioned. The position detection apparatus of any one of Claims.
The magnet specifying part is arranged such that the distance between magnets is shorter than 1 / n (n is an integer of 2 or more) of the effective detection length of the magnetic sensor and is magnetized in the same direction with respect to the moving direction. 3. The position detection device according to claim 1, wherein the permanent magnet facing the magnetic sensor is specified from a plurality of the permanent magnets based on a detection value of the permanent magnet.
  The magnet specifying unit is arranged such that the distance between the magnets is shorter than 1 / (n-1) (n is an integer of 2 or more) of the effective detection length of the magnetic sensor, and is alternately different from the moving direction. 4. The permanent magnet facing the magnetic sensor is specified from among the plurality of permanent magnets based on a detection value of n magnetized permanent magnets. 5. The position detection apparatus described in 1. 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 two sensors crosses zero, the magnetic field values of the two virtual sensors straddling zero are interpolated, and the position where the magnetic field value becomes zero is output as the position of the permanent magnet The position detection device according to claim 1, wherein:
The position signal generation unit calculates a position of the first permanent magnet facing the magnetic sensor, and faces the first permanent magnet and the magnetic sensor at the calculated position of the first permanent magnet. The position detecting device according to any one of claims 1 to 7, wherein the position of the second permanent magnet is output by adding a distance between the second permanent magnet and the second permanent magnet.
The position detection device according to claim 1, wherein the magnetic sensors are arranged at an equal pitch.
  Inter-magnet distance calculation that calculates the distances of the plurality of permanent magnets based on the positions of the plurality of permanent magnets calculated by the position signal generation unit when the plurality of permanent magnets are opposed to the magnetic sensor. The position detection device according to claim 1, further comprising a unit.

Images