JP6653341B2 - Position detection device - Google Patents

Description

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

  2. Description of the Related Art 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 a “magnet”) is known. For example, in Patent Document 1, a plurality of magnetic sensors are arranged on a straight line, and a magnetic field value detected by each magnetic sensor is interpolated by a straight line or a curve to obtain a point at which the magnetic field value becomes zero from a magnetic field distribution obtained. A conventional device for detecting the position of a magnet is disclosed.

  However, in this method, when the offset component of the magnetic field changes due to the influence of an external magnetic field such as terrestrial magnetism, there is a problem that the point at which the magnetic field value becomes zero is shifted and an error occurs. Similarly, even when the offset component changes due to the temperature characteristics of the magnetic sensor, the point at which the magnetic field value becomes zero is shifted, and an error occurs. Also, in order to increase the detection accuracy by linear interpolation, the number of magnetic sensors must be increased. Further, the detection range of the magnet is limited by the distance between the magnetic sensors at both ends of the arrayed magnetic sensors, and there is a problem that the effective detection length is short.

JP-A-8-50004

  As described above, in the conventional detection device, when detecting the magnetic field of the magnet, there has been a problem that an error is generated in the position detection value due to the influence of an external magnetic field such as terrestrial magnetism 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 terrestrial magnetism, or when the offset component similarly changes due to the temperature characteristics of the magnetic sensor and the like. It is another object of the present invention to provide a position detecting device which is not affected by the offset component and can increase the effective detection length without increasing the number of magnetic sensors.

  In order to solve the above-mentioned problem, a first technical means of the present invention includes a plurality of permanent magnets arranged at a predetermined distance, and arranged along a relative movement direction of the plurality of permanent magnets, The difference value between the M (M is an integer of 3 or more) magnetic sensors arranged in a direction in which the maximum detection value is output when the permanent magnet comes closest to each other, and the detection values of the two magnetic sensors one by one Virtual magnetic field value generation for generating (M−2) magnetic field values of the first group of virtual sensors as the magnetic field value of the virtual sensor positioned between the two skipped magnetic sensors. Unit, from the detection values of the plurality of magnetic sensors, a magnet identification unit that identifies the permanent magnet facing the magnetic sensor, the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field value of the virtual sensor is 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.

  A second technical means is the first technical means, wherein the virtual sensor magnetic field value generation unit further calculates a difference value between respective detection values of the adjacent magnetic sensors, and compares the difference value with the two adjacent magnetic sensor 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 outputting a 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 virtual sensor of the second group and the virtual sensor as the position of the permanent magnet specified by the magnet specifying unit. It is a feature.

  A third technical means is the first technical means or the second technical means, wherein the magnet identification unit faces the magnetic sensor from among the plurality of permanent magnets based on a polarity of a detection value of the magnetic sensor. It is characterized by specifying a permanent magnet.

  A fourth technical means is the electronic device according to any one of the first to third technical means, wherein the magnet identification unit is configured to select the magnetic field from a plurality of the permanent magnets based on a magnitude of a detection value of the magnetic sensor. It is characterized in that the permanent magnet facing the sensor is specified.

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

A sixth technical means is the image processing apparatus according to any one of the first to third technical means, wherein the magnet identification section 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 value of the magnetic sensor with respect to an integer greater than or equal to) n number of said permanent magnets that are magnetized in different directions alternately to shorter than provided by and the moving direction, wherein from the plurality of the permanent magnet The method is characterized in that the permanent magnet facing the magnetic sensor is specified.

  A seventh technical means is the electronic device according to any one of the first to sixth technical means, wherein the position signal generating unit specifies the magnetic sensor that outputs a maximum detection value among the magnetic sensors, It is determined whether the magnetic field value of the virtual sensor closest to the sensor and the magnetic field values of the virtual sensors before and after the virtual sensor cross over zero, and the magnetic field values of the two virtual sensors crossing zero And outputs a position where the magnetic field value becomes zero as the position of the permanent magnet.

  An eighth technical means is the electronic device according to any one of the first to seventh technical means, wherein the position signal generating section calculates a position of a first permanent magnet facing the magnetic sensor, and The position of the second permanent magnet is output by adding the inter-magnet 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 the following.

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

  A tenth technical means is the electronic device according to any one of the first to ninth technical means, wherein the plurality of permanent magnets calculated by the position signal generation unit are provided when the plurality of permanent magnets face the magnetic sensor. It is characterized by further comprising 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 terrestrial magnetism, or when the offset component similarly changes due to the temperature characteristics of the magnetic sensor or the like, it is not affected by the offset component. Furthermore, the detection accuracy can be increased without increasing the number of magnetic sensors, and the effective detection length can be lengthened. If the effective range is the same as the conventional one, the size of the detection device can be reduced.

It is a figure showing one composition of a position detecting device concerning an embodiment of the present invention. It is a figure which shows the specific relationship of arrangement | positioning of a magnet and a magnetic sensor. FIG. 3 is a diagram when a relative position between a magnet and a magnetic sensor is changed. FIG. 4 is a diagram for explaining characteristics of a detection value (magnetic field value) of a magnetic sensor with respect to a first magnet. FIG. 9 is a diagram for explaining characteristics of a difference value of each detection value of two magnetic sensors skipping when the first magnet faces the magnetic sensor. FIG. 3 is a diagram illustrating a relationship between a position of a magnetic sensor and a position of a first group of virtual sensors. FIG. 5 is a diagram illustrating an example of a processing flow in the position detection device according to the embodiment of the present invention. FIG. 4 is a diagram for describing linear interpolation for obtaining a position of a magnet. FIG. 9 is a diagram for explaining characteristics of a detection value (magnetic field value) of a magnetic sensor with respect to a second magnet. FIG. 7 is a diagram for explaining characteristics of a difference value of each detection value of two magnetic sensors skipping when a second magnet faces the magnetic sensor. It is a figure showing the case where only the 1st magnet is located within the effective detection length of a magnetic sensor. It is a figure showing the case where the 1st magnet and the 2nd magnet are located within the effective detection length of a magnetic sensor. It is a figure showing the case where only the 2nd magnet is located within the effective detection length of the magnetic sensor. FIG. 7 is a diagram for explaining characteristics of a difference value between respective detection values of two adjacent magnetic sensors when the first magnet faces the magnetic sensor. FIG. 4 is a diagram illustrating a relationship between a position of a magnetic sensor and a position of a virtual sensor obtained by combining a first group and a second group. It is a figure showing an example of a calculation flow of the distance between magnets. It is a figure showing other composition of a position detecting device concerning an embodiment of the present invention. FIG. 9 is a diagram illustrating still another configuration of the position detection device according to the embodiment of the present invention. FIG. 19 is a diagram for explaining a case where magnet positions are different in the position detection device shown in FIG. 18.

  Hereinafter, preferred embodiments of the position detection device of the present invention will be described with reference to the drawings. In the following description, configurations denoted by the same reference numerals in different drawings are the same, and description thereof may be omitted. It should be noted that the present invention is not limited to the exemplifications of these embodiments, but includes all changes within the scope of the matters described in the claims and within the equivalent scope.

(First embodiment)
FIG. 1 is a diagram showing one configuration of the position detecting device according to the first embodiment of the present invention. In the present embodiment, an example will be described in which two magnets, 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.

  The position detection device 1 includes a first magnet 10A and a second magnet 10B for detection, and a plurality of magnetic sensors MS and a plurality of magnetic sensors MS that detect the first magnet 10A and the second magnet 10B. 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 values of the magnetic sensor MS 40, an output circuit 50 for outputting a value calculated by the microcomputer 40 as an analog signal. In this specification, a magnetic sensor is described as a magnetic sensor MS when generically referred to without specifying a magnetic sensor, and a magnetic sensor is specified with a number such as a magnetic sensor MS2 when specifying a magnetic sensor. This is the same also about the virtual sensor mentioned later.

  The microcomputer 40 has a virtual sensor magnetic field value generation unit 41, a position signal generation unit 42, a magnet identification unit 43, an inter-magnet 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, a ROM, a RAM (not shown) of the microcomputer 40, and a control program stored in the ROM in advance.

  As the magnetic sensor MS, a sensor using a Hall element, a saturable coil, or the like can be used. As a device using a saturable coil, for example, a device utilizing the fact that a saturable coil is excited to the saturation region of a core and a saturation point of the core is moved by the action of an external magnetic field, for example, JP-A-2003-215221 Can be used.

  FIG. 2 is a diagram showing a specific relationship between the magnets and the magnetic sensors, and FIG. 3 is a diagram when the relative positions of the magnets and the magnetic sensors are changed. In the present embodiment, M, for example, 11 magnetic sensors MS are linearly arranged 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) at a distance L between the magnets, and both move in parallel to the substrate BS while keeping a fixed distance from the magnetic sensors MS1 to MS11. I do. The magnetization direction of the first magnet 10A is magnetized to the S-pole and the N-pole with respect to the moving direction, and the magnetization direction of the second magnet 10B is N-magnetized to the moving direction opposite to the first magnet 10A. It is magnetized into a pole and an S pole. The directions of the magnetizations may be opposite to each other. The magnetic sensor MS detects a horizontal magnetic field of the first magnet 10A and the second magnet 10B. The output characteristics of the detection values with respect to the magnet magnetic field 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 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 a pitch P, but the arrangement of the magnetic sensors MS may not be equal. In any case, it is assumed that the positions of the magnetic sensors MS1 to MS11 are stored in the microcomputer 40 in advance. Further, the number M of the magnetic sensors MS is not limited to 11, but requires three or more.

  In addition, the inter-magnet distance L between the first magnet 10A and the second magnet 10B is set to be shorter than the effective detection length A of the magnetic sensor MS, and is set to, for example, 70 mm in the present embodiment. I have. 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. 1 is the first magnet 10A or the second magnet 10A within a range from a position where the first magnet 10A faces the magnetic sensor MS2 to a position where the second magnet 10B faces the magnetic sensor MS10. The position of the magnet 10B can be detected. Therefore, the total effective detection length of the position detecting device 1 is the sum of the effective detection length A (80 mm) of the magnetic sensor MS and the distance L (70 mm) between the magnets, and is 150 mm.

First, a method of 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 which is a detection value of the magnetic sensor with respect to the first magnet. Note that the characteristics shown in FIG. 4 use a saturable coil for the magnetic sensor MS and neodymium φ5 × 6 for the first magnet 10A. The vertical axis in FIG. 4 indicates the internal value of the microcomputer 40 representing 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. And, 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 a detection value at a position where the position of the magnet is smaller than −10 mm, which is outside the effective detection length A of the magnetic sensor MS, but is not actually used for position detection.

  FIG. 4 shows magnetic field values which are detection values of the magnetic sensors MS1 to MS4. 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. When the first magnet 10A is located at a position of 10 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 10 mm. As described above, the detection value of each magnetic sensor MS becomes maximum 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 1 to MS 11 are sequentially switched according to a command from the multiplexer signal generation unit 45 of the microcomputer 40, and an analog signal from each magnetic sensor MS is converted into a digital signal by the A / D converter 30 and input to the microcomputer 40. .

  As shown in FIG. 4, it is difficult to detect the position of the first magnet 10A by finding the zero point of the magnetic field value by interpolating with a straight line or a curve if the detection value of the magnetic sensor MS remains unchanged. For this reason, in the present embodiment, a difference value is obtained every time the detection value of the magnetic sensor MS is skipped inside the microcomputer 40, and the obtained difference value is set to a virtual value located in the middle of the two skipped magnetic sensors MS. It is the magnetic field value of the sensor. Specifically, "detected value of magnetic sensor MS3-detected value of magnetic sensor MS1", "detected value of magnetic sensor MS4-detected value of magnetic sensor MS2", "detected value of magnetic sensor MS5-detected value of magnetic sensor MS3" "Value" ... "Detected value of magnetic sensor MS11-Detected value of magnetic sensor MS9", and the virtual sensors VL1, VL2, VL3,. The magnetic field value is VL9 (see FIG. 6 described later).

  FIG. 5 is a diagram for explaining the characteristic of the difference value between the detection values of the two magnetic sensors one by one when the first magnet faces the magnetic sensor, and FIG. FIG. 4 is a diagram illustrating a relationship between a position and a position of a first group of virtual sensors. The vertical axis in FIG. 5 indicates the internal value of the microcomputer 40 representing 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, the difference value between the detection values of the magnetic sensor MS1 and the magnetic sensor MS3 one by one from the magnetic sensor, that is, “the detection value of the magnetic sensor MS3−the magnetic sensor The “detected value of MS1” is calculated as the magnetic field value of the virtual sensor VL1 located between the magnetic sensor MS1 and the magnetic sensor MS3. In the case of 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 before and after the position 0 mm, the magnetic field value of the virtual sensor VL1 changes almost linearly. I have.

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 calculates the difference value of “the detected value of the magnetic sensor MS4−the detected value of the magnetic sensor MS2” by the magnetic field. Value. The characteristic of the virtual sensor VL2 is such 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 drawing) so that the magnetic field value becomes zero when the magnet is at the position of 10 mm. Characteristics.
Further, the virtual sensor VL3 becomes equal to the position of the magnetic sensor MS4, and has a magnetic field value equal to the difference value of “the detection value of the magnetic sensor MS5−the detection value of the magnetic sensor MS3”. The characteristic of the virtual sensor VL3 is a characteristic obtained by shifting the characteristic of the virtual sensor VL1 shown in FIG. 5 by 20 mm in the plus direction of the substrate BS.

  Thereafter, a difference value between the detection values of the two magnetic sensors MS one by one is sequentially obtained, and the obtained difference value is generated as a magnetic field value of the virtual sensor VL located in the middle of the magnetic sensor MS one by one. Then, finally, a difference value of “the detection value of the magnetic sensor MS11−the detection value of the magnetic sensor MS9” is obtained, and is set as the magnetic field value of the virtual sensor VL9 located at the same position as the magnetic sensor MS10. The characteristics of the virtual sensor VL9 are 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 set to 11, nine difference values of the magnetic sensors MS skipping one are obtained. In addition, since the magnetic sensors MS are arranged at the same pitch P, the intermediate position between the two magnetic sensors MS is one between the two magnetic sensors MS, as shown in FIG. It is equal to the position of the magnetic sensor MS located. As described above, in the present embodiment, nine virtual sensors VL of the virtual sensors VL1 to VL9 can be generated, and their positions are equal to the positions of the magnetic sensors MS2 to MS10, respectively. It is not necessary to arrange the magnetic sensors MS at the same pitch. In this case, the position of the virtual sensor VL may be an intermediate position between the magnetic sensors one by one based on the position of each magnetic sensor MS. In the present invention, a plurality of virtual sensors located between the two magnetic sensors MS that are skipped by one are referred to as a first group of virtual sensors.

  The microcomputer 40 interpolates the calculated magnetic field values of the virtual sensors VL1 to VL9 with a straight line or a curve, finds a zero point of the magnetic field value, and detects the position of the first magnet 10A. 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 processing the position of the first magnet 10A 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 the external magnetic field such as the terrestrial magnetism, the detection position of the first magnet 10A is maintained. Not affected. Further, even when the offset component similarly changes due to the temperature characteristics of the magnetic sensor MS, the detection position of the first magnet 10A is not affected. Therefore, even when the offset component of the magnetic field changes due to the influence of an external magnetic field such as terrestrial magnetism, or when the offset component similarly changes due to the temperature characteristics of the magnetic sensor MS, highly accurate position detection can be performed without being affected by these components. It is.

Next, a processing flow of the position detection device, including processing for detecting the position of the first magnet 10A using linear interpolation, will be described. FIG. 7 is a diagram illustrating an example of a processing flow in the position detection device 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 a signal from the multiplexer signal generation unit 45, and are converted into digital values. It is taken in. The acquisition of the detection value from the magnetic sensor MS into the microcomputer 40 may be performed in parallel with the processing flow shown in FIG.

  In step S1 of FIG. 7, first, 1 is set to a variable n. In step S2, the virtual sensor magnetic field value generation unit 41 shown in FIG. 1 calculates the difference between the detection values of the n-th and (n + 2) -th magnetic sensors MS, and in step S3, calculates the difference value between the n-th and (n + 2) -th magnetic sensors. 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 the value is not equal (in the case of NO), the process proceeds to step S5, where 1 is added to the variable n. 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, where the position signal generation unit 42 determines that the magnetic sensor MS that has output the maximum detection value (absolute value) The closest virtual sensor VL is specified.

  Next, the process proceeds to step S7, where the magnet identification unit 43 identifies a magnet to be subjected to position detection. This process is a process for identifying a magnet facing the magnetic sensor MS from among the plurality of magnets and identifying a magnet to be subjected to position detection, as described later. 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 closest to the magnetic sensor MS that has output the maximum detection value is specified, it is possible to roughly know the position of the first magnet 10A, and to determine the approximate position of the two virtual sensors VL. This is a reference for searching whether the magnetic field value crosses the zero point. Next, the process proceeds to step S8, and it is determined whether or not 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 over 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 value of the virtual sensors VL3 and VL5 immediately 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 straddles zero between the two virtual sensors, and the first magnet 10A is between the two virtual sensors. Will be.

  If the magnetic field value of the virtual sensor VL3 is plus, the magnetic field value of the virtual sensor VL4 is minus, and the magnetic field value of the virtual sensor VL5 is minus, the polarities of the magnetic field value of the virtual sensor VL3 and the magnetic field value of the virtual sensor VL4 are opposite. Therefore, it can be seen that the first magnet 10A is present between them. Then, in order to obtain the position of the first magnet 10A, the process proceeds to step S9, where the magnetic field values of the two virtual sensors VL crossing zero are linearly interpolated, and the position where the magnetic field value becomes zero is determined as the position of the first magnet 10A. Is calculated 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 the present embodiment, since the pitch P is 10 mm, the position of the virtual sensor VL3 is at the position of 20 mm, and the position of the virtual sensor VL4 is at the position of 30 mm. The position of the first magnet 10A is between 20 mm and 30 mm, and linear interpolation is performed between the magnetic field value of the virtual sensor VL3 and the magnetic field value of the virtual sensor VL4 to calculate the final magnet position. ing.

  FIG. 8 is a diagram for explaining linear interpolation for obtaining a magnet position. The vertical axis in FIG. 8 is an internal value of the microcomputer 40 representing the magnitude of the magnetic field, and the horizontal axis is a 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. The coordinate position is at point a, and the coordinate position of virtual sensor VL (n + 1) is indicated by point b. In the linear interpolation, the position of the magnet is obtained by obtaining the position of X at the intersection of the line connecting the points a and b and the line having the magnetic field value of zero.

  Here, the position of X is obtained by X = X0 + Y0 × (X1-X0) / (Y0-Y1) (Equation 1). For example, when X0 = 20, X1 = 30, Y0 = 100, and Y1 = −200, when applied to 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 of 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 has been described above. A method of detecting the position of the second magnet 10B when it is within the effective detection length A of the MS will be described.
FIG. 9 is a diagram for explaining the characteristic of the detection value (magnetic field value) of the magnetic sensor with respect to the second magnet. The second magnet 10B uses neodymium φ5 × 6 similarly to the first magnet 10A. are doing.

  In FIG. 9, for example, when the second magnet 10B is at the position of 0 mm, the detection 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. When the second magnet 10B is located at a position of 10 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. 9 are 10 mm. As described above, the detection value of each magnetic sensor MS becomes maximum when the center of the second magnet 10B and the center of the magnetic sensor MS are at the same position. That is, similarly to the case of the first magnet 10A, the polarity is different, but the magnetic sensor MS is arranged to output the maximum detection value when the second magnet 10B and the magnetic sensor MS are closest to each other. ing.

As shown in FIG. 9, it is difficult to detect the position of the second magnet 10B by finding the zero point of the magnetic field value by interpolating with a straight line or a curve if the detection value of the magnetic sensor MS remains unchanged. 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, the difference between the detected values of the magnetic sensor MS is obtained every time the microcomputer 40 skips one, and the magnetic field value of the virtual sensor located between the two magnetic sensors MS that are skipped by one is generated, and the magnetic field of the virtual sensor is generated. The position where the magnetic field value of the magnetic field distribution obtained by interpolating the value 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 inverting 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. 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 is on the minus side. For this reason, the first magnet 10A and the second magnet 10B can be distinguished, and the magnet specifying unit 43 specifies the magnet by using this characteristic.

  FIG. 10 is a diagram for explaining the characteristic of the difference value between the detection values of the two magnetic sensors one by one 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, but are shown in FIG. 5 when the first magnet 10A faces the magnetic sensor MS. 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 characteristic of the virtual sensor VL1.

  As described above, when the position of the second magnet 10B is detected, 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 the case of the position detection 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 closest to the magnetic sensor MS is specified. Further, it is determined whether or not the magnetic field value crosses the value of zero between the specified virtual sensor VL and the virtual sensors VL before and after the specified virtual sensor VL. If two virtual sensors crossing zero can be specified, the second magnet 10B is located between them, and the magnetic field values of the two virtual sensors VL are linearly interpolated to determine the position of the second magnet 10B.

  For example, when the magnetic sensor MS8 of the magnetic sensors MS2 to MS10 within the effective detection length A detects a negative maximum value, the virtual sensor closest to the magnetic sensor MS8 is the virtual sensor VL7. The polarity of the detection value of the sensor VL6 and the detection value of the virtual sensor VL7 and the polarity of the detection value of the virtual sensor VL7 and the detection value of the virtual sensor VL8 are compared. If the polarity is reversed, the magnetic field value crosses zero during that time, and the second magnet 10B is present.

  If the magnetic field value of the virtual sensor VL6 is minus, the magnetic field value of the virtual sensor VL7 is plus, and the magnetic field value of the virtual sensor VL8 is plus, the polarity of the magnetic field value of the virtual sensor VL6 is opposite to that of the virtual sensor VL7. 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 the present 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. The 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.

  Regarding the linear interpolation, although the inclination of the straight line shown in FIG. 8 is reversed, it 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 is obtained by X = X0 + Y0 × (X1−X0) / (Y0−Y1) (Equation 1). When X0 = 50, X1 = 60, Y0 = -100, and Y1 = 200 are applied to the 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 be.

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

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

  As shown in FIG. 11, when only the first magnet 10A is located 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, and the position is detected. The output value of the device 1 is used. 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 case is referred to as “case 2”. It is determined which of the magnet 10A and the second magnet 10B is given priority. For example, when giving priority to the first magnet 10 </ b> A, the position of the first magnet 10 </ b> A is determined as the output value of the position detection device 1, as in the case 1. As shown in FIG. 13, when only the second magnet 10B is located 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 determined, and the position of the second magnet 10B is determined. An output value of the position detecting device 1 is obtained by adding 70 mm, which is the distance L between magnets, to the value. When giving priority to the second magnet 10B in the second case, the same method as in the case 3 is used.

  Adding the inter-magnet distance L of 70 mm to the position of the second magnet 10B means that the first magnet 10A is out of the range of the effective detection length A of the magnetic sensor MS even though the first magnet 10A is outside the effective detection length A of the magnetic sensor MS. From the position of the first magnet 10A. As a result, as 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 to 150 mm, and the first magnet 10A and the second magnet 10B are switched. Even in this case, continuous position detection becomes possible. Also, 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 components such as the magnetic sensor MS and the substrate BS and to reduce the size of the device.

  Next, a method for reliably detecting each of the cases 1 to 3 in the present embodiment and preventing erroneous detection will be described. First, when detecting the first magnet 10A, a search is made for a magnetic sensor MS that outputs the maximum value on the plus side from the detected value of each magnetic sensor 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 with respect to the second magnet 10B, there is a negative maximum value at the position of 0 mm, but also has a maximum value on the plus side near ± 20 mm. The second magnet 10B causes the magnetic sensor MS to generate a positive detection value.

  If the value on the plus side of the second magnet 10B is erroneously detected, the first magnet 10A does not actually exist in the range of the effective detection length A even if there is no first magnet 10A but only the second magnet 10B. It is determined that there is, and normal position detection cannot be performed. For this reason, the positive value of the second magnet 10B is prevented from being 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 plus value of the second magnet 10B is not erroneously detected. , A threshold is provided for the detection value. For example, by not detecting a plus value having a magnetic field value of 100 or less as the threshold value of the detection value, it is possible to prevent the plus value of the second magnet 10B from being erroneously detected.

  Similarly, when the second magnet 10B is detected, 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 value on the minus side that is equal to or greater than the threshold value, the value on the minus side of the first magnet 10A is not erroneously detected.

  Thereby, the magnet identification unit 43 can reliably determine which of the cases 1 to 3 is in the state. 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 it is determined that the maximum value on both the plus side and the minus side is detected, it is determined that the case 2 has both the first magnet 10A and the second magnet 10B.

  As described above, in the present embodiment, it is possible to continuously detect the position of the first magnet 10A and the position of the second magnet 10B from the case 1 to the case 3. The position detection device 1 distinguishes 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 is possible to detect the position of the first magnet 10A outside the range of the effective detection length A. Further, from a different point of view, in case 1, as shown in FIG. 2 or 11, the position of the second magnet 10B outside the effective detection length A of the magnetic sensor MS is changed 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 increases by the distance L between the magnets.

(Second embodiment)
In the first embodiment, since the virtual sensor VL is generated by calculating the difference value for each of the two magnetic sensors MS skipped by one, the number of the virtual sensors VL is two less than the number of the magnetic sensors, and 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 a section ± 10 mm from the zero point of the magnetic field value (the interval between the magnetic sensors MS) is a straight line. As shown by the symbol C in FIGS. 5 and 10, the linearity deteriorates. Therefore, an error occurs when linear interpolation is performed using a value with poor linearity.

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

Hereinafter, a method of detecting the position of the first magnet 10A in the case 1 shown in FIG. 11 in which only the first magnet 10A is located within the effective detection length A of the magnetic sensor MS will be described.
FIG. 14 is a diagram for explaining a characteristic of a difference value between respective detection values of two adjacent magnetic sensors when the first magnet faces the magnetic sensor. FIG. It is a figure showing the position of the virtual sensor which combined the 1st group and the 2nd group. 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, a difference value of “the detection value of the magnetic sensor MS2−the detection value of the magnetic sensor MS1” is obtained, and the difference value is calculated by using the virtual sensor VL1 located at −5 mm between the magnetic sensor MS1 and the magnetic sensor MS2. , And a difference value of “the detection value of the magnetic sensor MS3−the detection value of the magnetic sensor MS1” is obtained, and this difference value is set to a virtual sensor located at a position of 0 mm located between the magnetic sensor MS1 and the magnetic sensor MS3. As the magnetic field value of VL2, a difference value of “the detection value of the magnetic sensor MS3−the detection value of the magnetic sensor MS2” is obtained, and this difference value is calculated for the virtual sensor VL3 located 5 mm between the magnetic sensor MS2 and the magnetic sensor MS3. As a magnetic field value, a difference value of “the detection value of the magnetic sensor MS4−the detection value of the magnetic sensor MS2” is obtained, and this difference value is determined as an intermediate value between the magnetic sensor MS2 and the 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 each have the same characteristic curve as the characteristic curve shown in FIG. The VL19 odd-numbered ten virtual sensors VL1, VL3, VL5... VL19 are generated from 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, and its magnetic field value becomes zero at the position of 5mm, and the magnetic field value before and after the zero point changes linearly. I have. 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. 11 by 10 mm in the minus direction of the substrate BS, and the characteristic of the virtual sensor VL5 is the characteristic of the virtual sensor VL3 of FIG. Is shifted by 10 mm in the plus direction of the substrate BS.

  Thereby, in the second embodiment, nine even-numbered first group virtual sensors VL having characteristics similar to the characteristics shown in FIG. 5 and ten virtual sensors VL having characteristics similar to the characteristics shown in FIG. Odd-numbered second group virtual sensors VL are generated at a pitch P ′ of 5 mm intervals as shown in FIG. This is the same as that 19 magnetic sensors are arranged at 5 mm intervals, 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 also 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 determined between the virtual sensors located at both ends along the arrangement direction of the magnetic sensors MS. It can be defined as equivalent to distance.

In the second embodiment, a 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 detection value is specified from among the magnetic sensors MS. 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 over zero. Is determined.

  For example, when the magnetic sensor MS5 has the maximum value, the virtual sensor VL closest to the magnetic sensor MS5 is the virtual sensor VL8. Therefore, the polarity of the magnetic field value of the virtual sensor VL8 and the virtual sensor VL8 adjacent to the virtual sensor VL8 The polarities of the magnetic field values of VL7 and VL9 are compared. If the polarities of the magnetic field values of the two virtual sensors VL are reversed, the magnetic field value straddles zero between the two virtual sensors, and the first magnet 10A is placed between the two virtual sensors. It means that there is.

  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 polarities of the magnetic field value of the virtual sensor VL7 and the magnetic field value of the virtual sensor VL8 are opposite. Therefore, it can be seen that the first magnet 10A is present between them. In the present 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 crossing 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 method of linear interpolation is the same as in the first embodiment. As described with reference to FIG. 8, the position X of the magnet is determined by X = X0 + Y0 × (X1-X0) / (Y0-Y1) (Equation 1). For example, when X0 = 25, X1 = 30, Y0 = 100, and Y1 = −200, if this expression 1 is applied, 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 of detecting the position of the first magnet 10A in the case 1 where only the first magnet 10A is located within the effective detection length A 'of the magnetic sensor MS has been described. In case 3, in which only the second magnet 10B is located within the effective detection length A 'of the magnetic sensor MS, the method of detecting the position of the second magnet 10B also has a positive or negative characteristic of the detection value of the magnetic sensor MS. It is the same as Case 1 except that it is reversed. Therefore, the description is omitted. In the case 2 where the first magnet 10A and the second magnet 10B are within the effective detection length A ', similarly to the first embodiment, the position is detected by giving priority to one of the magnets. do it.

  Since the characteristic of the second group of virtual sensors VL added in the present embodiment also calculates the difference between the detection values of the magnetic sensors MS, the present embodiment, like the first embodiment, has an external magnetic field such as terrestrial magnetism. Even when the offset component of the magnetic field changes due to the influence of the magnetic field, or when the offset component similarly changes due to the temperature characteristics of the magnetic sensor, etc., highly accurate position detection can be performed without being affected by these. In this embodiment, highly accurate position detection is possible even by linear interpolation without increasing the number of magnetic sensors, and the effective detection length A ′ is also 90 mm, which is more than the effective detection length A of 80 mm in the first embodiment. Can be longer.

(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 position of the second magnet 10B is The position of the first magnet 10A is output by adding the distance L between the magnets of 70 mm. However, since the inter-magnet distance 70 mm is a fixed value that does not take account of the installation error and the like, if the inter-magnet distance L is shifted due to the installation error and 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 range of 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 positions. 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 calculation unit 44 to the first magnet 10B. The position of the magnet 10A is output.

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

Next, a method of calculating the inter-magnet distance L in the case of the first embodiment will be described, but the same applies to the method of calculating the inter-magnet distance L in the case of the second embodiment.
FIG. 16 is a diagram illustrating an example of a calculation flow of the distance between magnets. First, the magnet identification unit 43 determines whether 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 (step S11). If both magnets are not within the effective detection length A, move the magnets and wait until both magnets are within 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 detection of the position of the first magnet 10A specifies the magnetic sensor MS that outputs the maximum detected value on the plus side, and checks whether the magnetic field values of the two virtual sensors VL close to the magnetic sensor MS cross zero. Then, the position of the first magnet 10A is obtained by 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 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 plus side of the detection value, that position is the position of the virtual sensor VL8, and the polarities of the magnetic field values of this virtual sensor VL8 and the preceding and following virtual sensors VL7, VL9 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. Has the first magnet 10A, and performs linear interpolation using the magnetic field values of the virtual sensor VL8 and the virtual sensor VL9.

  By the linear interpolation, the position X of the first magnet 10A is obtained by Expression 1: X = X0 + Y0 × (X1-X0) / (Y0-Y1). In the present 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 Expression 1.

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

  Since the distance L between the magnets of the first magnet 10A and the second magnet 10B is 70 mm, when both magnets are within the range of the effective detection length A, the second magnet 10B is located 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 becomes 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 the linear interpolation, the position X of the second magnet 10B is obtained by Expression 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 Equation (1), 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 sets the inter-magnet distance L from the position of the first magnet 10A to the second distance. 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, 73.333-5.000 = 68.333. Is 68.333 mm.

  If there is an installation error or the like in the inter-magnet distance L, for example, if the inter-magnet distance L is set to a fixed value of 70 mm in the first embodiment, the positions of the first magnet 10A and the second magnet 10B will be changed. When the detected value is switched, an error occurs in the output of the position detecting device 1 by a difference from the actual distance between the magnets. However, in this 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 magnet distance L from the position of each magnet is determined. Can be obtained. For this reason, 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 distance between the second magnets 10B is calculated by the inter-magnet distance calculation unit 44. By adding the actual value of the inter-magnet distance L to obtain the position of the first magnet 10A, it is possible to prevent an error from occurring.

(Fourth embodiment)
In the first to third embodiments, two magnets having different magnetization directions with respect to the moving direction have been described as an example in order to distinguish a plurality of magnets, but the magnetization directions may be the same. FIG. 17 is a diagram showing another configuration of the position detecting 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 detecting device includes a first magnet 10A and a second magnet 10B whose magnetization directions are arranged in the same direction as the movement direction, and the first magnet 10A and the second magnet 10B. Are arranged on the substrate BS at a pitch P of 10 mm at intervals P, for example, eleven magnetic sensors MS for detecting. The configurations of the magnetic sensor MS and the substrate BS are the same as 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, are arranged at intervals of, for example, 30 mm so that the distance L between the magnets is shorter than A / 2. This magnet arrangement is for specifying each magnet and detecting its absolute position even when a plurality of magnets having the same magnetization direction as the moving direction are used.

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

  Based on the detection value from the magnetic sensor MS, as shown in FIG. 17A, the magnet identification unit 43 determines whether one magnet is detected and the detected position is less than the effective detection length A / 2. , The detected magnet is specified as the first magnet 10 </ b> A, and 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. Also, as shown in FIG. 17B, when the number of detected magnets is two, the magnet identification unit 43 sets the magnetic sensor MS11 side to the first magnet 10A and the magnetic sensor MS1 side to the second magnet 10B. The position signal generation unit 42 specifies the position of the first magnet 10A as an output value of the position detection device 1 by giving priority to the position of the first magnet 10A, for example. Further, as shown in FIG. 17C, when the number of detected magnets is one and the detected position is a position equal to or longer than the effective detection length A / 2, the magnet specifying unit 43 determines that the detected magnet is the second one. The position signal generator 42 specifies 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 the length A + L obtained by adding the inter-magnet distance L to the effective detection length A of the magnetic sensor MS.

The case where two magnets are used has been described above. However, the number n of magnets having the same magnetization direction as the moving direction may be three or more. For example, when the number of magnets is n = 3, 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 a first magnet, a second magnet, and a third magnet from the side closer to the magnetic sensor MS11, the positional relationship of the magnets facing the magnetic sensor MS is as follows. In the case, the magnet identification unit 43 can identify the magnet facing the magnetic sensor MS based on the detection value from the magnetic sensor MS.

(Case 1 ′) When one magnet is detected and its detection position is less than the effective detection length A / n, that is, less than A / 3, the position of the first magnet can be specified.
(Case 2 ′) When two magnets are detected 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 three magnets are detected, the positions of all magnets can be specified.
(Case 4 ′) When two magnets are detected and the detection position of one of the magnets is equal to or more than 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 detection position is equal to or more than the effective detection length (A−A / n), that is, 2 × A / 3 or more, the position of the third magnet is determined. Can be identified.

  Then, 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 specification unit 43 and the distance L between the magnets. The total effective detection length as the position detection device is a length A + L obtained by adding the inter-magnet distance L of 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 detecting device is length A '+ L.

(Fifth embodiment)
In the first to third embodiments, in order to distinguish a plurality of magnets, two magnets having different magnetization directions with respect to the moving direction have been described as an example, but the number n of the magnets is more than two. Is also good. FIG. 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, a case where n = 3 is shown as the number n of magnets (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, in which the magnetization directions are alternately different from the moving direction, and the first magnet 10A, As a plurality of magnetic sensors MS for detecting the magnet 10A, the second magnet 10B, and the third magnet 10C, M pieces, for example, 11 pieces 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 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 a space. Similarly, the two magnets of the second magnet 10B and the third magnet 10C have an interval of, for example, 35 mm so that the distance L2 between the magnets is shorter than A / (n-1), that is, A / 2. It is arranged in a space. This magnet arrangement is for specifying each magnet and detecting its absolute position even when a plurality of magnets whose magnetization directions are alternately different from the moving direction are used.

  FIG. 18A shows a case where only the first magnet 10A is located within the effective detection length A of the magnetic sensor MS, and FIG. 18B shows a case where the first magnet 10A is located within the effective detection length A of the magnetic sensor MS. When the magnet 10A and the second magnet 10B are located, 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. 19 (A) shows the 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. 19 (B) shows the case where the magnetic sensor MS is located. 3 shows a case where only the third magnet 10C is located within the effective detection length A of FIG.

  Based on the detection value from the magnetic sensor MS, as shown in FIG. 18A, the magnet identification unit 43 detects one magnet and its detection position is less than the effective detection length A / (n-1). 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

  In addition, as shown in FIG. 18B, when the number of detected magnets is two, the maximum value of the detection value of the magnetic sensor MS by the first magnet 10A is on the plus side, and the magnetism by the second magnet 10B is large. The maximum value of the detection value of the sensor MS appears on the negative side. The magnet identification unit 43 identifies the first magnet 10A or the second magnet 10B by using this characteristic. For example, the position signal generation unit 42 determines the position of the first magnet 10A by the position detection device 1. Output value.

  Next, as shown in FIG. 18C, when all the magnets 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 three, the magnet identification unit 43 can identify all three magnets. The position signal generator 42 sets, for example, 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 the 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 the maximum value of the third magnet 10C is The maximum value of the detection value of the magnetic sensor MS appears on the plus side. The magnet identification unit 43 identifies the second magnet 10B or the third magnet 10C using this characteristic. For example, the position signal generation unit 42 determines the distance L1 between the magnets at the position of the second magnet 10B. The added value is output as the position of the first magnet 10A.

  As described above, in the present embodiment, when the number of detected magnets is two, there are two cases shown in FIGS. 18B and 19A, respectively. On the other hand, since the two magnets are magnetized alternately with polarity, the two magnets detected based on the polarity of the detection value of the magnetic sensor MS are the first magnet 10A and the second magnet 10B, or the second magnet 10B. 10B and the third magnet 10C can be determined. For example, two magnets can be specified by taking the difference between the positive maximum value and the negative maximum value of the detection value of the magnetic sensor MS and determining the polarity of the difference.

  Further, as shown in FIG. 19 (B), when one detected magnet is located at a position equal to or longer than the effective detection length (A−A / (n−1)), that is, at a position equal to or longer 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 the present embodiment, the total effective detection length of the position detection device is A + L, which is the sum of the effective detection length A of the magnetic sensor MS and the distance L (= L1 + L2) between the magnets located at both ends, and 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 identified by the magnet identification 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 inter-magnet distance L between the magnets at both ends to the effective detection length A of the magnetic sensor MS. Further, when this embodiment and the second embodiment are combined, the total effective detection length as the position detecting device is the length A '+ L. Note that the first embodiment corresponds to a case where the number n of magnets is set to two in the fifth embodiment. Further, the number n of the magnets may be four or more.

  The embodiment of the invention has been described. In the present embodiment, in order to distinguish a plurality of magnets, a case where the magnetization direction is the same as a case of a plurality of magnets having different magnetization directions with respect to the moving direction has been described as an example, but a plurality of magnets having different magnetization strengths are described. May be used, and the detection range of the position detection device may be further extended by combining these magnets. When a plurality of magnets having different magnetization strengths are used, when each magnet is opposed to the magnetic sensor MS, it is necessary to use a magnet having a strength that can sufficiently discriminate a difference between the maximum values of the detection values of the magnetic sensor. desirable. In any case, the magnetic sensor MS needs to arrange the magnet and the magnetic sensor so that the maximum detection value is output when the magnet comes closest. Thereby, the absolute position of the magnet can be detected, and the position can be detected even when the initial power supply 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 Unit, 43: magnet identification unit, 44: inter-magnet distance calculation unit, 45: multiplexer signal generation unit, 50: output circuit, BS: substrate, MS: magnetic sensor, VL: virtual sensor.

Claims (10)

A plurality of permanent magnets arranged at a predetermined distance,
M (M is an integer of 3 or more) magnets arranged along a relative movement direction of the plurality of permanent magnets and arranged so as to output a maximum detection value when the permanent magnets are closest to each other. Sensors and
A difference value between the detection values of the two skipped magnetic sensors is calculated, and the magnetic field value of the virtual sensor positioned between the two skipped ones of the magnetic sensors is calculated as (M−2) first magnetic field values. A virtual sensor magnetic field value generation unit that generates a magnetic field value of the group of virtual sensors;
From the detection values of the plurality of magnetic sensors, a magnet identification unit that identifies the permanent magnet facing the magnetic sensor,
A position signal generating 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 is zero as the position of the permanent magnet specified by the magnet specifying unit,
A position detecting device comprising:
The virtual sensor magnetic field value generation unit further calculates a difference value between the respective detection values of the adjacent magnetic sensors, and calculates the difference value as a magnetic field value of a virtual sensor positioned between the two adjacent magnetic sensors. As a result, the magnetic field values of the (M−1) second group of virtual sensors are calculated,
The position signal generator, the position where the magnetic field value of the magnetic field distribution obtained by interpolating the magnetic field value of the virtual sensor including the first group of virtual sensors and the second group of virtual sensors, is zero, The position detecting 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 specification part specifies the said permanent magnet which opposes the said magnetic sensor among several said permanent magnets based on the polarity of the detection value of the said magnetic sensor, The Claim 1 or 2 characterized by the above-mentioned. Position detection device.
The said magnet specification part specifies the said permanent magnet which opposes the said magnetic sensor among several said permanent magnets based on the magnitude of the detection value of the said magnetic sensor, The Claims 1 to 3 characterized by the above-mentioned. The position detecting device according to claim 1.
The magnet identification unit is provided with n pieces of magnets having a distance between magnets shorter than 1 / n (n is an integer of 2 or more) of an effective detection length of the magnetic sensor and magnetized in the same direction with respect to the moving direction. based on the detection value of the magnetic sensor relative to the permanent magnet, the position detecting device according to the plurality of the permanent magnets to claim 1 or 2, characterized in that identifying the permanent magnet facing the magnetic sensor . The magnet identification unit is disposed 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. based on the detection value of the magnetic sensor with respect to said n permanent magnets magnetized, claims 1, wherein the identifying the permanent magnet facing the magnetic sensor from a plurality of the permanent magnet 3 The position detecting device according to any one of claims 1 to 7. The position signal generation unit specifies the magnetic sensor that outputs a maximum detection value among the magnetic sensors, and determines a magnetic field value of the virtual sensor closest to the magnetic sensor and the virtual sensor before and after the virtual sensor. Discriminating whether the magnetic field value of the virtual sensor crosses zero, interpolating the magnetic field values of the two virtual sensors crossing zero, and outputting a position where the magnetic field value becomes zero as the position of the permanent magnet. The position detecting device according to any one of claims 1 to 6, wherein:
The position signal generation unit calculates a position of a first permanent magnet facing the magnetic sensor, and, at the calculated position of the first permanent magnet, faces the first permanent magnet and the magnetic sensor. The position detection device according to any one of claims 1 to 7, wherein the position of the second permanent magnet is output by adding the inter-magnet distance to a second permanent magnet that is not present.
The position detecting device according to any one of claims 1 to 8, wherein the magnetic sensors are arranged at an equal pitch.
  When the plurality of permanent magnets face the magnetic sensor, an inter-magnet distance calculation that calculates a distance between the plurality of permanent magnets based on the positions of the plurality of permanent magnets calculated by the position signal generation unit. The position detecting device according to claim 1, further comprising a unit.

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