JP2012208112A - Position sensor, magnet member and manufacturing method for magnet member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a variation in linearity of sensor output to a movement position of a detection object and detect the movement position of the detection object with a higher degree of accuracy.SOLUTION: A position sensor (1) of the invention comprises: a magnet member (3) that includes a main magnetic field generation part (31) which generates a main magnetic field (F) and magnetic field correction parts (32) which are adjacent to magnetic pole parts on both ends of the main field generation part (31) and corrects the main magnetic field (F); and a magnetic sensor element that is arranged separately from a surface of the magnet member (3) and outputs signals corresponding to a parallel component and a vertical component of magnetic flux density in the main magnetic field (F). The magnet member (3) is magnetized by a magnetization yoke that includes a convex magnetization surface whose curvature radius is 1/2 or more and 1/1 or less of a magnetization pitch. The position sensor (1) detects a movement position of the magnet member (3) relative to the magnetic sensor element, based on output of the magnetic sensor element.

Description

  The present invention relates to a position sensor that magnetically detects the position of an object to be detected, a magnet member used for the position sensor, and a method for manufacturing the magnet member, and more particularly to an on-vehicle position sensor.

  2. Description of the Related Art Conventionally, a position sensor that uses a dipole magnet is known as a position sensor that magnetically detects the position of a detection target (see, for example, Patent Document 1). In this position sensor, a dipole magnet is attached to a detection object, a magnetic sensor element is arranged away from the magnet surface, and the magnetic flux density that changes due to the linear movement of the detection object corresponds to a component perpendicular to the magnet surface. The position of the detection object is detected. The magnet surface facing the magnetic sensor element is formed to bulge in a round shape in a side view along the moving direction. As a result, the magnetic flux density acting on the magnetic sensor element is changed linearly with respect to the movement position of the detection object.

JP 2010-60338 A

  However, in the conventional position sensor as described above, since the position of the detection target is detected by the orthogonal component of the magnetic flux density, the orthogonal component of the magnetic flux density is not affected by the gap variation between the magnet and the magnetic sensor element. It fluctuates greatly. For this reason, there has been a problem that the linearity of the sensor output with respect to the movement position of the detection object varies greatly according to the gap variation between the magnet and the magnetic sensor element.

  The present invention has been made in view of such a situation, and can suppress the fluctuation of the linearity of the sensor output with respect to the movement position of the detection target object and detect the movement position of the detection target object with higher accuracy. It aims at providing a manufacturing method of a position sensor, a magnet member, and a magnet member.

  The position sensor of the present invention includes a main magnetic field generator that forms a main magnetic field by a plurality of magnetic poles magnetized at equal intervals so as to have different polarities alternately in a straight line, and magnetic poles at both ends of the main magnetic field generator A magnet member having a magnetic field correction unit magnetized so as to correct the main magnetic field, and spaced apart from the surface of the magnet member, the magnet member at a magnetic flux density of the main magnetic field A magnetic sensor element that outputs a signal corresponding to a parallel direction component parallel to the direction of arrangement of the magnetic pole portions and a vertical direction component perpendicular to the surface of the magnet member, and a period of the signal corresponding to the parallel direction component; The magnet member is arranged so that the period of the signal according to the vertical direction component substantially matches, and the amplitude of the signal according to the parallel direction component substantially matches the amplitude of the signal according to the vertical direction component. Magnetized and the magnetic sensor Based on the output of the device, and detecting a relative position between said magnet member and the magnetic sensor element in the direction of arrangement of the magnetic pole portions.

  The magnet member of the present invention is arranged so as to face the magnetic sensor element, and in the magnet member for constituting the position sensor, it is arranged so as to be alternately different in a straight line for forming the main magnetic field. A main magnetic field generator having a plurality of magnetic pole portions, and a pair of magnetic pole portions each having a different polarity with respect to the magnetic pole portions at both ends of the main magnetic field generator for correcting the main magnetic field generated by the main magnetic field generator A magnetic field correction unit, and the period of the signal corresponding to the parallel direction component output from the magnetic sensor element substantially coincides with the period of the signal corresponding to the vertical direction component, and the signal corresponding to the parallel direction component It is characterized in that the amplitude and the amplitude of the signal corresponding to the vertical direction component are substantially matched.

  The method for manufacturing a magnet member according to the present invention is a method for manufacturing a magnet member that is arranged to face a magnetic sensor element and constitutes a position sensor. A main magnetic field generating unit having a plurality of magnetic poles arranged so as to be, and a pair of magnetic poles different from the magnetic poles at both ends of the main magnetic field generating unit for correcting the main magnetic field When the magnetic field correction unit has a magnetized pitch as a distance between adjacent different poles in the main magnetic field generating unit, a convex magnetized surface having a radius of curvature of 1/2 or more and 1/1 or less of the magnetization pitch The period of the signal corresponding to the parallel direction component output from the magnetic sensor element substantially coincides with the period of the signal corresponding to the vertical direction component, and the signal corresponding to the parallel direction component is Depending on amplitude and vertical component Wherein the signal amplitude is magnetized so as to be substantially coincident.

  According to these configurations, the main magnetic field is corrected by the magnetic field correction unit, and the parallel direction component and the vertical direction component of the magnetic flux density due to the main magnetic field are brought close to a sine wave shape or cosine wave shape having a desired period and amplitude. Therefore, the relative position between the magnet member and the magnetic sensor element is detected with high accuracy based on the signals corresponding to the parallel direction component and the vertical direction component of the magnetic flux density. In this case, even if the gap between the magnet member and the magnetic sensor element changes, the amplitude ratio of the parallel direction component and the vertical direction component of the magnetic flux density does not change, so that the change in linearity of the sensor output can be suppressed.

  In the position sensor of the present invention, the magnetic field correction unit may be configured to cause the main magnetic field to be generated by a pair of magnetic pole portions magnetized so as to have different polarities from the magnetic pole portions at both ends of the main magnetic field generation unit. Can be corrected. According to this configuration, the main magnetic field can be corrected with a simple configuration.

  In the position sensor of the present invention, the magnetic field correction unit can be formed narrower than the magnetization pitch of the main magnetic field generation unit in the direction in which the magnetic pole units are arranged. According to this configuration, it is possible to reduce the size by reducing the dimension in the direction of the arrangement of the magnetic poles of the magnet member.

  In the position sensor of the present invention, the magnet member is movable in the direction in which the magnetic pole portions are arranged with respect to the magnetic sensor element. According to this configuration, the position of the detection object provided with the magnet member can be detected with high accuracy.

  Further, the position sensor of the present invention has a calculation unit capable of performing signal processing on the output of the magnetic sensor element, and the magnet member is a signal corresponding to the parallel direction component by signal processing of the calculation unit. And the amplitude of the signal corresponding to the vertical direction component are substantially magnetized. According to this configuration, it is possible to obtain a signal corresponding to the parallel component and a signal corresponding to the vertical component within a range that can be corrected by the signal processing of the calculation unit.

  In the position sensor of the present invention, the maximum value of each of the positive and negative amplitudes of the signal corresponding to the vertical direction component is a predetermined value based on the maximum value of each of the positive and negative amplitudes of the signal corresponding to the parallel direction component. It is in range. According to this configuration, it is possible to easily match the amplitude of the signal corresponding to the vertical component with the amplitude of the signal corresponding to the parallel component by signal processing for correction.

  In the position sensor of the present invention, the magnet member may have a radius of curvature that is 1/2 or more of the magnetization pitch 1/1 when the distance between adjacent different poles in the main magnetic field generation unit is a magnetization pitch. It is magnetized by a magnetizing yoke having the following convex magnetized surface. According to this configuration, a sinusoidal magnetic field distribution can be obtained from the magnet member.

  In the position sensor of the present invention, the main magnetic field generation unit of the magnet member is arranged so as to correspond to a range that can move relatively with respect to the magnetic sensor element. According to this configuration, the relative position between the magnet member and the magnetic sensor element can be easily calculated from the main magnetic field.

  ADVANTAGE OF THE INVENTION According to this invention, the fluctuation | variation of the linearity of the sensor output with respect to the movement position of a detection target object can be suppressed, and the movement position of a detection target object can be detected more accurately.

It is a whole block diagram of the position sensor which concerns on this Embodiment. It is explanatory drawing which shows the change of the magnetic flux density with respect to the movement distance which concerns on this Embodiment. It is explanatory drawing which shows the change of the magnetic flux density with respect to the movement distance which concerns on a comparative example. It is explanatory drawing of the magnetization structure by the magnetizing yoke which concerns on this Embodiment. It is a figure which shows the relationship between the curvature radius of a magnetizing yoke, and the detection accuracy of a position sensor. It is a figure which shows the relationship between the output voltage which concerns on this Embodiment, and the movement position of a magnet member. It is a figure which shows the modification of a magnet member. It is explanatory drawing of the detection method of the movement position of a detection target object by the perpendicular direction component of magnetic flux density. It is a figure which shows an example of the signal processing by the calculation unit which concerns on this Embodiment. It is a figure which shows an example of the calculation result of the linearity error after the signal processing by the calculation unit which concerns on this Embodiment. It is a figure which shows an example of the change of the linearity error with respect to the amplitude ratio of the cosine wave signal which concerns on this Embodiment.

  In a position sensor or the like, a magnet member is attached to a detection object that is vertically separated from the magnetic sensor, and the movement position when the detection object moves in parallel with respect to the magnetic sensor can be detected with high accuracy. It is desired. In this case, as shown in FIG. 8A, in the method of detecting the moving position of the magnet member 73 based on the vertical direction component of the magnetic flux density, the magnetic flux density greatly changes according to the gap fluctuation between the magnetic sensor 74 and the magnet member 73. The linearity fluctuated greatly, and sufficient detection accuracy could not be obtained.

  For example, when the pole pitch (adjacent N pole-S pole distance) of the magnet member 73 is 28 [mm] and the relative stroke between the magnet member 73 and the magnetic sensor 74 is ± 14 [mm], the magnet member When the relationship between the magnetic flux density and the position of the magnet member 73 was examined by changing the gap between the magnetic sensor 73 and the magnetic sensor 74 in units of 1.0 [mm], the result shown in FIG. 8B was obtained. Here, when the gap between the magnetic sensor 74 and the magnet member 73 fluctuates from 4.0 [mm] to ± 1 [mm], the variation amount of the linearity becomes ± 11%, and the detection accuracy greatly decreases. For this reason, the present inventors have devised a method for detecting the moving position of the detection object by obtaining the arc tangent from the parallel direction component and the vertical direction component of the magnetic flux density.

  In this method, the parallel component and the vertical component of the magnetic flux density change at the same time due to the gap variation, and the amplitude ratio does not change, so that the variation in linearity is suppressed. However, in order to suppress the variation in linearity, it is necessary to magnetize the magnet member so that the parallel component of the magnetic flux density changes to an appropriate sine wave shape and the vertical component changes to an appropriate cosine wave shape. Therefore, as a result of investigating the number of magnetic poles of the magnet member, the present inventors have provided magnetic pole portions for converging the main magnetic field on both outer sides of the three magnetic pole portions forming the main magnetic field. It was discovered that the parallel direction component and the vertical direction component of the magnetic flux density can be appropriately changed.

  Further, as a result of examining the magnetized yoke, the present inventors have magnetized the magnet member with a convex magnetized surface having a radius of curvature of 1/2 or more and 1/1 or less of the magnetization pitch. It was discovered that a sinusoidal magnetic field distribution can be obtained from the member. That is, the gist of the present invention is magnetized by using a magnetized yoke having this magnetized surface, and by using a magnet member having a magnetic pole part for correction, the variation in sensor output linearity is suppressed and detected. It is to detect the movement position of the object with high accuracy.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the following description, for convenience of explanation, the same name is given the same reference numeral. The overall configuration of the position sensor will be described with reference to FIG. FIG. 1 is an overall configuration diagram of a position sensor according to an embodiment of the present invention. In FIG. 1, the magnet member is viewed from the side, and the longitudinal direction of the magnet member is the X direction and the thickness direction is the Y direction.

  As shown in FIG. 1, the position sensor 1 has a magnet member 3 attached to the detection target 2 and a magnetic sensor 4 arranged away from the surface of the magnet member 3 in the vertical direction (Y direction). The parallel movement of the detection object 2 with respect to the magnetic sensor 4 is detected. A calculation unit 5 is connected to the magnetic sensor 4, and the movement position of the detection target 2 in the parallel direction (X direction) is calculated in the calculation unit 5.

  The magnet member 3 is a 5-pole magnetized flat plate magnet formed in a rectangular shape when viewed from above, and is fixed to the surface of the detection object 2 facing the magnetic sensor 4. The magnet member 3 is configured by alternately magnetizing N poles and S poles on the surface facing the magnetic sensor 4 at equal pitches in the longitudinal direction. The magnetizing pitch of the magnet member 3 is set to the half stroke (14 [mm] in the present embodiment) of the detection object 2. An arc-shaped magnetic field from the N pole to the S pole is generated between adjacent different poles of the magnet member 3.

  In the magnet member 3, the three magnetic pole portions at the center function as the main magnetic field generating portion 31 that generates the main magnetic field F, and the pair of magnetic pole portions at both ends function as the magnetic field correcting portion 32 that corrects the main magnetic field F. In the position sensor 1, the detection object 2 is moved between the same polar pitches at both ends of the main magnetic field generation unit 31, and the movement position of the detection object 2 is detected according to the magnetic flux density of the main magnetic field F. The magnetic field correction unit 32 converges the magnetic field spreading outward from the magnetic poles at both ends of the main magnetic field generation unit 31, and distributes the main magnetic field F in an appropriate range.

  The magnetic sensor 4 is disposed in a housing (not shown) so as to face the surface of the magnet member 3, and is composed of a magnetic sensor element such as a Hall element or a magnetoresistive effect element. As a basic configuration, the magnetoresistive effect element is formed by laminating an antiferromagnetic layer, a pinned layer, an intermediate layer, and a free layer on a wafer (not shown). In the pinned layer, the magnetization direction is fixed in one direction by an antiferromagnetic layer, and in the free layer, the magnetization direction is changed in response to an external magnetic field. Then, the magnetization direction of the free layer is changed by the magnetic field formed by the magnet member 3, and the resistance change rate is varied according to the angle formed with the magnetization direction of the pinned layer, so that an output signal reflecting this is output.

  The calculation unit 5 calculates the moving position of the magnet member 3 based on the amplifiers 51 and 52 that amplify the sine wave signal and the cosine wave signal output from the magnetic sensor 4 and the output signals amplified by the amplifiers 51 and 52. A position calculation unit 53. The position calculation unit 53 calculates an arc tangent of the sine wave signal and the cosine wave signal input via the amplifiers 51 and 52, calculates a magnetic field angle, and calculates a moving position of the magnet member 3 from the calculated magnetic field angle. .

  The calculation unit 5 includes a processor that executes various processes of the position sensor 1, a memory, and the like.

  With reference to FIG.2 and FIG.3, the change of the magnetic flux density with respect to the moving distance of a magnet member is demonstrated. FIG. 2 is an explanatory diagram showing changes in the magnetic flux density with respect to the moving distance according to the present embodiment. FIG. 3 is an explanatory diagram showing a change in magnetic flux density with respect to a moving distance according to a comparative example. The comparative example is different from the present embodiment in that the magnet member is a tripolar magnet. 2A and 3A mainly show schematic side views of the magnet member, and FIGS. 2B and 3B show changes in magnetic flux density. 2B and 3B, the vertical axis represents the magnetic flux density, the horizontal axis represents the detection position, the solid line W1 represents the vertical component of the magnetic flux density, and the broken line W2 represents the parallel component of the magnetic flux density.

  As shown in FIG. 2A, in the magnet member 3 according to the present embodiment, a magnetic field is generated from the N pole toward the adjacent S pole, and the magnetic field rotates 180 degrees while moving from the N pole to the S pole. To do. At this time, the main magnetic field F generated from the central main magnetic field generator 31 is corrected by the magnetic field correction units 32 at both ends. Specifically, in the magnetic pole portions (S poles) at both ends of the main magnetic field generator 31, the outward magnetic field bulge is suppressed by the adjacent magnetic pole portions (N poles) of the magnetic field correction unit 32. As a result, the distribution range of the main magnetic field F is matched to the two pitches of the magnetization pitch, that is, the movement range of the detection target 2.

  Therefore, the main magnetic field F rotates 180 degrees clockwise between one magnetic pole L1 directed in one direction from the center position of the main magnetic field generating unit 31 and one magnetic pole directed in the other direction from the center position of the main magnetic field generating unit 31. It rotates 180 degrees counterclockwise in the interval L1. The magnetic sensor 4 outputs a signal corresponding to the moving position of the detection target object 2 by the change in the horizontal direction component and the vertical direction component of the magnetic flux density due to the rotation of the main magnetic field F. The vertical component of the magnetic flux density is output as a cosine wave output signal, and the horizontal component of the magnetic flux density is output as a sine wave output signal.

  As shown in FIG. 2B, the vertical direction component of the magnetic flux density that changes in the cosine wave shape of the solid line W <b> 1 vibrates at a period that matches the moving range of the detection target 2. In the movement range of the detection object 2, there is an amplitude difference between the amplitude in the positive direction and the amplitude in the negative direction, but it is suppressed to the extent that the detection result is not greatly affected. Similarly, the parallel direction component of the magnetic flux density indicated by the sine wave of the broken line W2 is also oscillating at a period that coincides with the movement range of the detection target 2. In the horizontal component of the magnetic flux density, there is no amplitude difference between the positive amplitude and the negative amplitude.

  For example, when the magnetization pitch of the magnet member 3 (movement range of the detection target 2) is ± 14 [mm] and the gap between the magnet member 3 and the magnetic sensor element is 6 [mm], the magnetic flux is indicated by the solid line W1. The amplitude difference between the positive and negative amplitudes of the vertical component of the density is suppressed to about 50 [gauss], and the period of the horizontal component of the magnetic flux density is 28 [mm] in each of the solid line W1 and the broken line W2. ± 14 [mm]). Thus, when the magnet member 3 according to the present embodiment is used, a sine wave signal and a cosine wave signal having an appropriate period and amplitude are obtained based on a change in magnetic flux density due to the main magnetic field F.

  On the other hand, as shown in FIG. 3A, in the magnet member 3 according to the comparative example, the main magnetic field F is generated by the three magnetic pole portions. At this time, the magnet member 3 is not provided with a magnetic pole portion that suppresses the magnetic field of the magnetic pole portions (S poles) at both ends, so that the magnetic field at the magnetic pole portions at both ends expands outward. As a result, the distribution range of the main magnetic field F is shifted outward from the movement range of the detection target 2. Therefore, the main magnetic field F rotates 180 degrees clockwise from the center position of the magnet member 3 at a distance L2 wider than one magnetic pole L1 from the center position to the other direction side from the center position of the magnet member 3. On the other hand, it rotates 180 degrees counterclockwise at an interval L2 wider than L1 between the magnetic poles.

  As shown in FIG. 3B, the vertical component of the magnetic flux density that changes in the cosine wave shape of the solid line W <b> 1 vibrates at a period that matches the moving range of the detection target 2. In the movement range of the detection object 2, the amplitude difference between the positive direction and the negative direction is larger than the amplitude difference according to the present embodiment described above. Further, the parallel direction component of the magnetic flux density that changes in a sine wave shape of the broken line W2 has an amplitude larger than the moving range of the detection target object 2.

  For example, when the magnetization pitch of the magnet member 3 is 14 [mm], the movement range of the detection target 2 is ± 14 [mm], and the gap between the magnet member 3 and the magnetic sensor element is 6 [mm], a solid line At W1, the amplitude difference between the positive and negative amplitudes of the vertical component of the magnetic flux density is about 150 [gauss], and at the broken line W2, the period of the horizontal component of the magnetic flux density is 30 [mm] (± 15 [Mm]). When the magnet member 3 according to the comparative example is used, the amplitude difference of the vertical direction component of the magnetic flux density at the solid line W1 is about three times as compared with the case where the magnet member 3 according to the present embodiment is used. The period of the horizontal component of the magnetic flux density at the broken line W2 is increased by 1 [mm] on the outside. Therefore, when the magnet member 3 according to the comparative example is used, a sine wave signal and a cosine wave signal having an appropriate period and amplitude cannot be obtained based on a change in magnetic flux density due to the main magnetic field F.

  As described above, in the magnet member 3 according to the present embodiment, the magnetic field correction unit 32 including a pair of magnetic pole portions is provided on both outer sides of the main magnetic field generation unit 31 including the three magnetic pole portions, so The bulge to the direction is suppressed. For this reason, while the amplitude difference of the vertical direction component of magnetic flux density can be made small, the period of the horizontal direction component of magnetic flux density can be made to correspond to the movement range of detection object 2, and an appropriate sine wave signal and cosine wave signal can be obtained. It is possible to obtain.

  Next, a magnetizing method of the magnet member by the magnetizing yoke will be described with reference to FIGS. FIG. 4 is an explanatory diagram of a magnetizing configuration by the magnetizing yoke according to the present embodiment. FIG. 5 is a diagram showing a relationship between the radius of curvature of the magnetized yoke according to the present embodiment and the detection accuracy of the position sensor. FIG. 4A shows a magnetized yoke according to the present embodiment, and FIGS. 4B to 4D show magnetic field distributions generated by the magnet member. FIG. 5A shows the relationship between the radius of curvature, the amount of change in linearity, and the amplitude ratio, and FIG. 5B shows the relationship between the radius of curvature and the magnetic flux density.

  As shown in FIG. 4A, the magnetizing yoke 6 according to the present embodiment is formed in a rectangular shape in a top view corresponding to the magnet member 3, and has a plurality of convex shapes arranged at equal intervals in the longitudinal direction. It has a magnetized portion 61 and a winding 62 wound around each magnetized portion 61. The protruding end side of the magnetized portion 61 is a magnetized surface 63 having an arc shape in cross section. When the winding 62 is energized, the magnetized portion 61 is alternately magnetized to the S pole and the N pole. Since the cross section of the magnetized surface 63 is arcuate, relatively large magnetic flux lines pass through the magnet member 3.

  Here, when the inventor changed the magnitude of the radius of curvature r of the magnetized surface 63 with respect to the magnetization pitch L of the magnet member 3, as shown in FIG. 4B, the radius of curvature r was magnetized. It has been found that the magnetic field distribution of the magnet member 3 is substantially sinusoidal in the range of 1/2 to 1/1 of the pitch L. The magnetic field distribution approaches a trapezoidal wave shape as shown in FIG. 4C when the radius of curvature r is larger than 1/1 of the magnetization pitch L, and when the radius of curvature r is smaller than 1/2 of the magnetization pitch L. As shown in FIG. 4D, it has been found that it approaches a triangular wave shape.

  Further, when the relationship between the radius of curvature and the position sensor was examined with the magnetization pitch L = 14 [mm], the result shown in FIG. 5 was obtained. As shown in FIG. 5A, when the curvature radius r is larger than 1/1 (14 [mm]) of the magnetization pitch L, the amount of change in linearity increases. Further, when the radius of curvature r is smaller than 1/2 (7 [mm]) of the magnetization pitch L, the amplitude ratio is lowered and the calculation accuracy by the position calculation unit 53 is decreased. Furthermore, as shown in FIG. 5B, when the radius of curvature r is smaller than 1/2 (7 [mm]) of the magnetization pitch L, the vertical direction component and the horizontal direction component of the magnetic flux density are drastically lowered, and the detection sensitivity is increased. descend.

  As described above, in this embodiment, the magnet member 3 is magnetized by the magnetizing yoke 6 having the magnetized surface 63 having the radius of curvature r of 1/2 or more and 1/1 or less of the magnetization pitch L. An appropriate magnetic field distribution is generated in the member 3.

  By using the magnet member 3 magnetized as described above, each direction component of the magnetic flux density changes into a sine wave shape and a cosine wave shape as shown in FIG. 2B, and the sine wave signal and the cosine wave signal from the magnetic sensor 4. Is output to the calculation unit 5. In the calculation unit 5, an arc tangent is obtained from these output signals, and an output voltage corresponding to the moving position of the magnet member 3 is calculated. Here, when the relationship between the output voltage and the moving position of the magnet member 3 was examined, the result shown in FIG. 6 was obtained.

  FIG. 6 is a diagram showing the relationship between the output voltage and the moving position of the magnet member according to the present embodiment. In FIG. 6, the left vertical axis represents the output voltage, the right vertical axis represents the amount of change in linearity, and the horizontal axis represents the moving position of the magnet member. In FIG. 6, a solid line W3 is an ideal output characteristic (reference straight line), a broken line W4 is an output characteristic when the gap between the magnet member and the magnetic sensor element is 4.5 [mm], and a broken line W5 is a magnet member. The output characteristics when the gap between the magnetic sensor element and the magnetic sensor element is 5.5 [mm], and the broken line W6 indicates the output characteristics when the gap between the magnet member and the magnetic sensor element is 6.5 [mm]. .

  As shown in FIG. 6, in the position sensor 1 according to the present embodiment, even when the gap between the magnetic sensor element of the magnet member 3 and the magnetic sensor 4 is changed, the ideal linear characteristic of the solid line W3. A linear characteristic that substantially overlaps with the above can be obtained. The amount of change in linearity at this time is suppressed to ± 0.5% or less even when the gap changes from 5.5 [mm] to ± 1 [mm] as indicated by the broken line W4-W6. Therefore, compared with the method of detecting the moving position of the detection target object 2 by the vertical direction component of the magnetic flux density shown in FIG.

  As described above, in this embodiment, an ideal magnetization condition is found for the magnet member 3, and by using this magnet member 3, the variation in linearity with respect to the gap variation is suppressed. In this case, the magnet member 3 only needs to have the correction magnetic pole portion magnetized outside the plurality of magnetic pole portions that generate the main magnetic field F. For example, the main magnetic field F may be generated by four or more magnetic pole portions, or the main magnetic field F may be corrected by two or more magnetic pole portions. 7A, in the magnet member 3, the main magnetic field generation unit 31 and the magnetic field correction unit 32 may be formed separately. Furthermore, as shown in FIG. 7B, the width of the magnetic field correction unit 32 may be formed narrower than the magnetization pitch of the main magnetic field generation unit 31 in the longitudinal direction of the magnet member 3. / 2 or less may be sufficient.

  By the way, although the amount of fluctuation of linearity can be suppressed small by using the above-described magnet member 3, depending on the specifications required for the position sensor 1, it may be difficult to suppress the linearity to a desired amount of fluctuation only by the magnet member 3. is there. When the calculation unit 5 determines that the linearity fluctuation amount is not within the allowable range, the linearity fluctuation amount is adjusted by correcting the output from the magnetic sensor 4 in the calculation unit 5. In this case, the calculation unit 5 has a small amplitude difference between the cosine wave signal indicating the vertical direction component of the magnetic flux density and the sine wave signal indicating the parallel direction component of the magnetic flux density so that the fluctuation amount of the linearity falls within the allowable range. It is corrected so that Therefore, the magnet member 3 may have an amplitude difference between the vertical direction component and the horizontal direction component of the magnetic flux density as long as it is within a range that can be adjusted by the signal processing for correction of the calculation unit 5.

  Hereinafter, signal processing for correction by the calculation unit will be described with reference to FIGS. 9 to 11. FIG. 9 is a diagram illustrating an example of signal processing by the calculation unit according to the present embodiment. In FIG. 9, the left vertical axis indicates the magnetic flux density, and the horizontal axis indicates the moving position of the magnet member. Although FIG. 9 shows an example of correcting the amplitude of the cosine wave signal with respect to the sine wave signal, the amplitude of the sine wave signal may be corrected with respect to the cosine wave signal, or the cosine wave signal and the sine wave may be corrected. Both of the signals may be corrected.

  In the magnetic flux density distribution shown in FIG. 9A, the amplitude (magnetic flux density) of the cosine wave signal and the sine wave signal is positive and negative and symmetric. In this case, the amplitude difference between the cosine wave signal and the sine wave signal on the positive side matches the amplitude difference between the cosine wave signal and the sine wave signal on the negative side. The calculation unit 5 is configured to perform gain adjustment (correction) by expanding and contracting the amplitude of the signal waveform as a whole. For this reason, the amplitude of the cosine wave signal and the sine wave signal are aligned on both the positive and negative sides by adjusting (correcting) the amplitude of the cosine wave signal in the calculation unit 5. Thereby, the fluctuation | variation of a linearity is suppressed smaller.

  On the other hand, in the magnetic flux density distribution shown in FIG. 9B, the amplitude (magnetic flux density) of the cosine wave signal and the sine wave signal is positive and negative and asymmetric. In this case, the amplitude of the sine wave signal is larger than that of the cosine wave signal on the positive side, and the amplitudes of the cosine wave signal and the sine wave signal match on the negative side. That is, the amplitude difference between the cosine wave signal and the sine wave signal on the positive side does not match the amplitude difference between the cosine wave signal and the sine wave signal on the negative side. As described above, since the calculation unit 5 generally expands and contracts the amplitude of the signal waveform, even if the gain of the cosine wave signal is adjusted by the calculation unit 5, the amplitudes of the cosine wave signal and the sine wave signal are positive and negative. Not complete.

  In the example of FIG. 9B, when the amplitude of the cosine wave signal approaches the amplitude of the sine wave signal on the positive side, the amplitude of the cosine wave signal is corrected so as to deviate from the amplitude of the sine wave signal on the negative side. However, even with such correction, the fluctuation in linearity can be suppressed to some extent by reducing the amplitude difference between the cosine wave signal and the sine wave signal.

  Next, the relationship between the amplitude difference between the cosine wave signal and the sine wave signal and the linearity error will be described. FIG. 10 is a diagram illustrating an example of a calculation result of linearity error after signal processing by the calculation unit according to the present embodiment. In the left and center diagrams of FIG. 10, the left vertical axis indicates the magnetic flux density, and the horizontal axis indicates the moving position of the magnet member. In the right diagram of FIG. 10, the left vertical axis indicates the magnetic field angle, the right vertical axis indicates the amount of change in linearity, and the horizontal axis indicates the moving position of the magnet member. 10 shows an example of correcting the amplitude of the cosine wave signal with respect to the sine wave signal, the amplitude of the sine wave signal may be corrected with respect to the cosine wave signal, or the cosine wave signal and the sine wave may be corrected. Both of the signals may be corrected.

  For convenience of explanation, FIG. 10 shows an example in which the amplitude of the cosine wave signal is corrected in a state where the amplitudes of the cosine wave signal and the sine wave signal are matched on the negative side, but the present invention is not limited to this. Regardless of the magnetic flux density distribution of FIG. 10, the linearity error is calculated according to the amplitude difference between the cosine wave signal and the sine wave signal.

  FIG. 10A shows a waveform in which the positive amplitude ratio of the cosine wave signal to the sine wave signal is 70%. The amplitude of the cosine wave signal is 30% smaller than the amplitude of the sine wave signal on the positive side and matches the amplitude of the sine wave signal on the negative side. In the calculation unit 5, the gain is adjusted so that the amplitude of the cosine wave signal is increased by ± 15%. At this time, the amplitude of the cosine wave signal is close to 15% of the amplitude of the sine wave signal on the positive side, and the amplitude of the cosine wave signal is separated from the amplitude of the sine wave signal by 15% on the negative side. Then, the arc tangent of the cosine wave signal and sine wave signal after gain adjustment is obtained, whereby the output characteristic corresponding to the moving position of the magnet member 3 is calculated. The linearity error at this time is about ± 1.25% with respect to the ideal straight line.

  FIG. 10B shows a waveform in which the positive amplitude ratio of the cosine wave signal to the sine wave signal is 85%. The amplitude of the cosine wave signal is 15% smaller than the amplitude of the sine wave signal on the positive side and matches the amplitude of the sine wave signal on the negative side. In the calculation unit 5, the gain is adjusted so that the amplitude of the cosine wave signal is increased by ± 7.5%. At this time, the amplitude of the cosine wave signal is close to 7.5% of the amplitude of the sine wave signal on the positive side, and the amplitude of the cosine wave signal is separated from the amplitude of the sine wave signal by 7.5% on the negative side. Then, the arc tangent of the cosine wave signal and sine wave signal after gain adjustment is obtained, whereby the output characteristic corresponding to the moving position of the magnet member 3 is calculated. The linearity error at this time is about ± 0.65% with respect to the ideal straight line.

  As a result of examining the amplitude ratio of the cosine wave signal to the sine wave signal and the linearity error, the relationship shown in FIG. 11 was obtained. FIG. 11 is a diagram illustrating an example of a change in linearity error with respect to the amplitude ratio of the cosine wave signal according to the present embodiment. In FIG. 11, the left vertical axis indicates the linearity error, and the horizontal axis indicates the amplitude ratio of the cosine wave signal.

  As shown in FIG. 11, the amplitude ratio of the cosine wave signal and the linearity error have a proportional relationship. As described above, when the amplitude ratio of the cosine wave signal is 70%, the linearity error is ± 1.25%, and when the amplitude ratio of the cosine wave signal is 85%, the linearity error is ± 0.65%. ing. From such a proportional relationship, an appropriate amplitude ratio of the cosine wave signal is obtained according to the specifications required for the position sensor 1. For example, when the specification required for the position sensor 1 is a linearity error of ± 0.5%, the amplitude ratio of the cosine wave signal needs to be set to 89% or more. That is, if the magnet member 3 is magnetized so that the amplitude difference between the cosine wave signal and the sine wave signal can be corrected within ± 5.5% (11%), the position sensor is processed by the signal processing of the calculation unit 5. 1 specification is satisfied.

  Thus, the magnet member 3 is worn so that the amplitude difference between the vertical direction component and the parallel direction component of the magnetic flux density is within the range satisfying the specifications of the position sensor 1 by the signal processing for correction of the calculation unit 5. It only has to be magnetized. 11 illustrates the linearity error with respect to the amplitude ratio of the cosine wave signal, the linearity error with respect to the amplitude ratio of the sine wave signal has a similar proportional relationship. The signal processing for correction by the calculation unit 5 may be performed by the position calculation unit 53 or may be performed by the amplifiers 51 and 52. Further, the calculation unit 5 may be provided with a signal processing unit, and the signal processing unit may perform signal processing for correction.

  As described above, according to the position sensor 1 according to the present embodiment, the position sensor 1 is magnetized by the magnetized surface 63 having the radius of curvature r of 1/2 or more and 1/1 or less of the magnetization pitch, and the magnetic pole portions at both ends. By suppressing the main magnetic field F, the parallel direction component and the vertical direction component of the magnetic flux density due to the main magnetic field F change to a sine wave shape or a cosine wave shape having a desired period and amplitude. Therefore, the position of the magnet member 3 is accurately detected based on the signal corresponding to the parallel direction component and the vertical direction component of the magnetic flux density.

  In the above-described embodiment, the magnetic sensor element is configured as a magnetoresistive effect element such as a Hall element or a GMR element (giant magnetoresistive effect element). However, the present invention is not limited to this configuration. Any magnetic field generated by the magnet member may be used as long as it can output a signal corresponding to the horizontal component and the vertical component of the magnetic flux density.

  In the above-described embodiment, the calculation unit 5 performs arctangent calculation on the vertical direction component and the parallel direction component of the magnetic flux density to detect the moving position of the detection target 2. However, the present invention is not limited to this. Not. The calculation unit 5 may perform any calculation as long as the movement position of the detection target 2 can be calculated from the vertical direction component and the parallel direction component of the magnetic flux density.

  In the above-described embodiment, the position sensor 1 detects the moving position of the magnet member 3 that moves parallel to the magnetic sensor element. However, the present invention is not limited to this. The position sensor 1 detects a relative position between the magnetic sensor element and the magnet member. For example, the position sensor 1 may detect a moving position of the magnetic sensor element that moves in parallel with the magnet member 3. The relative movement position when the magnetic sensor element and the magnetic sensor element move in parallel may be detected.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  As described above, the present invention has an effect that the movement position of the detection target object can be detected with higher accuracy by suppressing the fluctuation of the linearity of the sensor output with respect to the movement position of the detection target object. In particular, it is useful for a vehicle-mounted position sensor that magnetically detects the position of a detection target.

DESCRIPTION OF SYMBOLS 1 Position sensor 2 Object to be detected 3 Magnet member 31 Main magnetic field generation part 32 Magnetic field correction part 4 Magnetic sensor 5 Calculation unit 51, 52 Amplifier 53 Position calculation part 6 Magnetization yoke 61 Magnetization part 62 Winding 63 Magnetization surface

Claims (10)

A main magnetic field generating section for forming a main magnetic field by a plurality of magnetic pole sections magnetized at equal intervals so as to have different polarities alternately in a straight line; and adjacent to the magnetic pole sections at both ends of the main magnetic field generating section; A magnet member having a magnetic field correction unit magnetized to correct the magnetic field;
Depending on the parallel direction component parallel to the direction of the arrangement of the magnetic pole portions of the magnet member and the vertical direction component perpendicular to the surface of the magnet member in the magnetic flux density of the main magnetic field, spaced apart from the surface of the magnet member A magnetic sensor element that outputs
The period of the signal according to the parallel direction component and the period of the signal according to the vertical direction component substantially coincide, and the amplitude of the signal according to the parallel direction component and the amplitude of the signal according to the vertical direction component Are magnetized so that they substantially match,
A position sensor that detects a relative position between the magnet member and the magnetic sensor element in a direction in which the magnetic pole portions are arranged based on an output of the magnetic sensor element.   2. The magnetic field correction unit corrects the main magnetic field by a pair of magnetic pole portions magnetized so as to be different in polarity from the magnetic pole portions at both ends of the main magnetic field generation unit. The position sensor described in 1.   3. The position sensor according to claim 1, wherein the magnetic field correction unit is formed narrower than a magnetization pitch of the main magnetic field generation unit in a direction in which the magnetic pole units are arranged.   4. The position sensor according to claim 1, wherein the magnet member is movable in a direction in which the magnetic pole portions are arranged with respect to the magnetic sensor element. 5. A calculation unit capable of performing signal processing on the output of the magnetic sensor element;
The magnet member is magnetized so that an amplitude of a signal corresponding to the parallel direction component and an amplitude of a signal corresponding to the vertical direction component are substantially matched by signal processing of the calculation unit. Item 2. The position sensor according to Item 1.   The maximum value of each of the positive and negative amplitudes of the signal corresponding to the vertical direction component is within a predetermined range based on the maximum value of each of the positive and negative amplitudes of the signal corresponding to the parallel direction component. The position sensor according to any one of claims 1 to 5.   The magnet member has a convex magnetized surface having a radius of curvature of ½ or more and 1/1 or less of the magnetization pitch when a distance between adjacent different poles in the main magnetic field generation unit is a magnetization pitch. The position sensor according to claim 1, wherein the position sensor is magnetized by a magnetizing yoke.   The position sensor according to claim 4, wherein the main magnetic field generation unit of the magnet member is arranged so as to correspond to a range in which the main magnetic field generation unit can move relative to the magnetic sensor element. In the magnet member arranged to face the magnetic sensor element and constituting the position sensor,
A main magnetic field generator having a plurality of magnetic pole portions arranged to be different from each other in a straight line to form a main magnetic field;
A magnetic field correction unit having a pair of magnetic pole parts different from the magnetic pole parts at both ends of the main magnetic field generation part for correcting the main magnetic field by the main magnetic field generation part,
The period of the signal corresponding to the parallel direction component output from the magnetic sensor element and the period of the signal corresponding to the vertical direction component substantially coincide with each other, and the amplitude of the signal corresponding to the parallel direction component and the vertical direction component are A magnet member that is magnetized so that the amplitude of the corresponding signal is substantially the same. In the manufacturing method of the magnet member for arranging the position sensor, facing the magnetic sensor element,
A main magnetic field generating unit having a plurality of magnetic pole portions arranged to be alternately different in a straight line to form a main magnetic field, and both ends of the main magnetic field generating unit for correcting the main magnetic field A magnetic field correction unit having a pair of magnetic poles each having a different polarity with respect to the magnetic poles of
When the distance between adjacent different poles in the main magnetic field generating portion is a magnetization pitch, a magnetizing yoke having a convex magnetized surface having a radius of curvature of 1/2 or more and 1/1 or less of the magnetization pitch,
The period of the signal corresponding to the parallel direction component output from the magnetic sensor element and the period of the signal corresponding to the vertical direction component substantially coincide with each other, and the amplitude of the signal corresponding to the parallel direction component and the vertical direction component are A method for manufacturing a magnet member, wherein the magnets are magnetized so that the amplitudes of the corresponding signals are substantially the same.

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