JP2009008519A - Mobile body detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile body detection device capable of comparing positional information of a magnetic material rotator or a magnetic material linear mobile body when the power supply is turned on with a conventional technique and accurately detecting it. <P>SOLUTION: The outer peripheral surface of a soft magnetic material rotator 10 comprises top parts 13a-13f where distances from the rotation center O become maximum, minimum parts 14a-14f where distances from the rotation center O become minimum, first surfaces 11a-11f extending from respective top parts on the front side in the rotation direction, and second surfaces 12a-12f extending from respective top parts on the back side in the rotation direction. Each minimum part exists between adjacent top parts. On each first surface, the distance from the rotation center O monotonically increases from the edge opposite to each top part toward each top part. On each second surface, the distance from the rotation center O monotonically decreases from each top part toward the edge opposite to each top part. Each minimum part is positioned at the edge opposite to each top part on the first and second surfaces. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for detecting position information of a magnetic material moving body from a magnetic field change accompanying the movement of the magnetic material moving body, for example, a magnetic material rotating body or a magnetic material linear moving body used in an industrial machine tool or an automobile engine. The present invention relates to a mobile body detection apparatus suitable for use in detecting position information.

The present applicant has already proposed a moving body detection device that detects a magnetic field change accompanying movement of a magnetic material moving body using a spin valve type giant magnetoresistive element (hereinafter referred to as “SV-GMR element”) (the following patent). Reference 1).
Japanese Patent Laid-Open No. 2005-233795

  FIG. 10 is an exemplary schematic perspective view of the moving object detection device 800 described in Patent Document 1. FIG. 11 is a front view of the moving object detection apparatus 800 shown in FIG. The soft magnetic gear 80 as the magnetic material moving body has irregularities on the outer peripheral surface. Specifically, there are a total of six convex portions 802a to 802f at an angle from the rotation center O every approximately 60 °, and the convex portions are narrower than the concave portions. The upper surface of each convex portion is at a distance r1 from the rotation center O, and the bottom surface of each concave portion is at a distance r2 from the rotation center O (r1> r2). The soft magnetic gear 80 having such a shape is used, for example, to detect the rotation angle of the shaft. The first SV-GMR element MR1 to the fourth SV-GMR element MR4 connected in a full bridge are fixedly arranged with respect to the bias magnet 50 so that the magnetosensitive surface faces the outer peripheral surface of the soft magnetic gear 80.

  FIG. 12 is an explanatory diagram of the principle configuration and magnetic characteristics of the SV-GMR element. The magnetosensitive surface of the SV-GMR element has a magnetoresistive film that forms a magnetosensitive pattern. The magnetoresistive film is formed by laminating a ferromagnetic pinned layer, a nonmagnetic layer, and a ferromagnetic free layer. The magnetization direction of the pinned layer is fixed regardless of the external magnetic field H, while the magnetization direction of the free layer is changed by the external magnetic field H. The magnetic characteristics of the SV-GMR element are such that the direction of the external magnetic field and the pinned layer magnetization direction are forward parallel and the resistance change rate (ΔR / R) is negative, the direction of the external magnetic field and the pinned layer magnetization direction are antiparallel and the resistance change. The rate (ΔR / R) is positive. That is, the SV-GMR element has a low resistance when the direction of the external magnetic field and the pinned layer magnetization direction are forward parallel, and has a high resistance when the direction of the external magnetic field and the pinned layer magnetization direction are antiparallel.

  As shown in an enlarged view in FIG. 10, the pinned layer magnetization directions of the first SV-GMR element MR1 and the third SV-GMR element MR3 are substantially opposite to the rotation direction of the soft magnetic gear 80, and the second SV-GMR element The pinned layer magnetization direction of the MR2 and the fourth SV-GMR element MR4 is substantially the forward direction of the rotation direction of the soft magnetic gear 80.

  When the convex portion of the soft magnetic gear 80 approaches the magnetic sensitive surface of the first SV-GMR element MR1 to the fourth SV-GMR element MR4, the magnetic material rotation tangential direction of the magnetic field at the magnetic sensitive surface position of each SV-GMR element The component is directed in the direction in which the convex portion approaches (substantially opposite to the rotational direction of the soft magnetic gear 80). At this time, the first SV-GMR element MR1 and the third SV-GMR element MR3 have a low resistance, and the second SV-GMR element MR2 and the fourth SV-GMR element MR4 have a high resistance due to the magnetic characteristics described above.

  On the other hand, when the convex portion of the soft magnetic gear 80 moves away from the magnetosensitive surface of the first SV-GMR element MR1 to the fourth SV-GMR element MR4, the magnetic body rotation tangential component of the magnetic field at the magnetosensitive surface position of the SV-GMR element Indicates a direction in which the convex portion moves away (substantially forward direction of the rotation direction of the soft magnetic gear 80). At this time, the first SV-GMR element MR1 and the third SV-GMR element MR3 have a high resistance, and the second SV-GMR element MR2 and the fourth SV-GMR element MR4 have a low resistance due to the magnetic characteristics described above.

  As the soft magnetic gear 80 rotates, the convex portions 802a to 802f of the soft magnetic gear 80 approach and move away from the magnetic sensing surfaces of the first SV-GMR element MR1 to the fourth SV-GMR element MR4 in turn. Repeated as the body gear 80 rotates. For this reason, the magnetic material rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element repeats the same change every time the soft magnetic gear 80 rotates about 60 °. Therefore, a detection signal that changes with the rotation of the soft magnetic gear 80 is obtained by connecting the first SV-GMR element MR1 to the fourth SV-GMR element MR4 with a full bridge. The detection signal is converted into a rectangular wave signal by, for example, a Schmitt trigger circuit, and the rotation information of the soft magnetic gear 80 can be detected based on the rectangular wave signal.

  In the case of the shape of the soft magnetic gear 80 as shown in FIGS. 10 and 11, the magnetic rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element as the soft magnetic gear 80 rotates is While it changes rapidly in the vicinity of the edge of the convex portion of the soft magnetic gear 80 for a short period, it hardly changes in the vicinity of 0 on the convex surface and the concave surface (portion forming the circumferential surface) away from the edge. That is, the detection signal obtained from the first SV-GMR element MR1 to the fourth SV-GMR element MR4 connected in full bridge changes only when the edge of the convex portion of the soft magnetic gear 80 passes over each SV-GMR element. When the convex surface and the concave surface away from the edge pass over each SV-GMR element, they are the same size and hardly change (see FIG. 4B described later).

  Accordingly, the level of the rectangular wave signal when the convex surface or the concave surface away from the edge passes over each SV-GMR element is such that the edge of the convex portion of the soft magnetic gear 80 immediately before the SV-GMR element It is determined by the change in the detection signal when it passes above (hereinafter referred to as “change immediately before the detection signal”). However, information on the immediately preceding change of the detection signal (information indicating whether the front edge or the rear edge of the convex portion has passed over each SV-GMR element) is not usually present when the power is turned on. Therefore, when the power is turned on with the convex surface and the concave surface (parts forming the circumferential surface) separated from the edge being directly above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, each SV-GMR element It is indefinite whether it faces the convex surface or the concave surface of the soft magnetic gear 80 when the power is turned on. Then, the rotational angle position of the soft magnetic gear 80 when the power is turned on does not correspond to the output (rectangular wave signal) of the moving body detection device 800, and as a result, an erroneous rectangular wave signal may be output. This problem is the same when detecting the movement of a linear moving body such as a rack.

  The present invention has been made after such considerations, and the purpose of the present invention is to make it possible to accurately detect the position information of the magnetic material rotating body or the magnetic material linear moving body when the power is turned on as compared with the prior art. The object is to provide a body detection device.

The moving body detection apparatus according to the first aspect of the present invention includes:
A magnetic material including a magnetic material rotating body, a bias magnetic field generating means, and at least one spin-valve giant magnetoresistive element fixed to the bias magnetic field generating means so as to face the outer peripheral surface of the magnetic material rotating body. A detection unit and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit, A moving body detection device for detecting rotation information;
The outer peripheral surface of the magnetic material rotating body is:
The top from which the distance from the rotation center of the magnetic material rotating body is maximized;
A minimal portion where the distance from the rotation center of the magnetic material rotating body is minimal;
A first surface extending forward from the top in the rotational direction;
A second surface extending from the top to the rear side in the rotational direction,
In the first surface, the distance from the rotation center monotonously increases from the edge opposite to the top toward the top.
In the second surface, the distance from the rotation center monotonously decreases from the top toward the edge opposite to the top.
An edge of the first and second surfaces opposite to the top portion is located at the minimum portion, and the same number of the minimum portions as the top portion is present.

  In the moving body detection apparatus according to the first aspect, there are a plurality of the top portions, the first surface extends from each of the plurality of top portions in the rotational direction, and the second surface is formed of the plurality of top portions. You may extend from the rear side in the rotational direction.

  In the moving body detection apparatus according to the first aspect, the first surface is a flat surface, the second surface is a curved surface that protrudes outward from the outer peripheral surface, and the minimal portion is a bent portion. Good.

The moving body detection apparatus according to the second aspect of the present invention includes:
A magnetic material including a magnetic material rotating body, a bias magnetic field generating means, and at least one spin-valve giant magnetoresistive element fixed to the bias magnetic field generating means so as to face the outer peripheral surface of the magnetic material rotating body. A detection unit and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit, A moving body detection device for detecting rotation information;
The outer peripheral surface of the magnetic material rotating body is:
A plurality of top portions having a maximum distance from the rotation center of the magnetic material rotating body;
There is only one location between adjacent top portions, and the deep portion where the depth based on the plane passing through the adjacent top portions is maximum,
A first surface extending from each top to the front side in the rotational direction;
A second surface extending from each top to the rear side in the rotational direction,
In the first surface, the depth monotonously decreases from the edge opposite to the top to the top.
In the second surface, the depth monotonously increases from the tops toward the edges opposite to the tops,
An edge of the first and second surfaces opposite to the tops is located in the extreme deep part.

  In the moving body detection device of the second aspect, the first and second surfaces may be flat surfaces, and the extreme deep portion may be a bent portion.

  In the moving body detection device according to the first or second aspect, the angle formed by the first surface with respect to the rotation center of the magnetic material rotating body is such that the second surface is at the rotation center of the magnetic material rotating body. It is better that the angle is smaller than the angle formed.

The moving body detection apparatus according to the third aspect of the present invention includes:
Magnetic material linear moving body having an uneven surface, bias magnetic field generating means, and at least one spin valve type fixedly disposed to the bias magnetic field generating means so as to face the uneven surface of the magnetic material linear moving body A magnetic detection unit including a giant magnetoresistive element and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit A moving body detecting device for detecting position information of the magnetic material linear moving body,
The uneven surface of the magnetic material linear moving body is:
A plurality of tops where the height is maximum,
There is only one place between the adjacent tops, and the minimum part has a minimum height,
A first surface extending from the top to the front side in the movement direction;
A second surface extending from each top to the rear side in the moving direction,
In the first surface, the height increases monotonously from the edge opposite to the top to the top.
In the second surface, the height decreases monotonously from each top to the edge opposite to each top,
The minimum portion is located on an edge of the first and second surfaces opposite to the top portions.

  In the moving body detection device of the third aspect, when the distance between the front and rear edges of the first surface in the moving direction is shorter than the distance between the front and rear edges of the second surface in the moving direction. Good.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the moving body detection apparatus of the present invention, the resistance value of the spin valve type giant magnetoresistive element changes for a longer period than the prior art due to the action of the first and second surfaces on the bias magnetic field. As a result, the period during which the output signal from the magnetic detection unit does not change with the same magnitude is shorter than in the prior art. Therefore, it is possible to accurately detect the position information of the magnetic material rotating body or the magnetic material linear moving body when the power is turned on, as compared with the prior art.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

(First embodiment)
FIG. 1 is an exemplary schematic perspective view of a moving body detection apparatus 100 according to the first embodiment of the present invention. FIG. 2 is a front view of the moving object detection apparatus 100 shown in FIG. FIG. 3 is a circuit diagram of the moving object detection apparatus 100 shown in FIG.

  The moving body detecting apparatus 100 includes a soft magnetic rotating body 10 as a magnetic material rotating body, a bias magnet 50 as a bias magnetic field generating means, and a first SV-GMR element MR1 to a fourth SV-GMR element MR4 constituting a magnetic detection unit. With. The plate-like or columnar soft magnetic rotator 10 is attached to a rotation shaft (not shown), and the outer peripheral surface of the soft magnetic rotator 10 changes in distance from the rotation center O according to the angle around the rotation center O as will be described later. . The first SV-GMR element MR1 to the fourth SV-GMR element MR4 are fixedly arranged in a row in the thickness direction of the soft magnetic rotator 10 so as to face the outer peripheral surface of the soft magnetic rotator 10, and a bias magnetic field is generated behind them. A bias magnet 50 as a means is fixedly arranged. As a result, the first SV-GMR element MR1 to the fourth SV-GMR element MR4 are magnetically biased by the bias magnet 50 and applied to the first SV-GMR element MR1 to the fourth SV-GMR element MR4 as the soft magnetic rotator 10 rotates. The magnetic field changes. The first SV-GMR element MR1 to the fourth SV-GMR element MR4 are connected in a full bridge as shown in FIG. 3 to form a magnetic detection unit 120, and a detection signal Vdet that changes as the soft magnetic rotator 10 rotates is detected. Output from the magnetic detection unit 120.

  The bias magnet 50 is a permanent magnet having, for example, an N pole on the surface facing the outer peripheral surface of the soft magnetic rotator 10 and an S pole on the opposite surface. The first SV-GMR element MR1 to the fourth SV-GMR element MR4 are bias magnets 50, respectively. It is located between the N pole surface and the outer peripheral surface of the soft magnetic rotator 10. The lateral width of the bias magnet 50 is the same as that of the first SV-GMR element MR1 to the fourth SV-GMR element MR4 so that a uniform magnetic field can be applied to the first SV-GMR element MR1 to the fourth SV-GMR element MR4 arranged linearly. It is desirable that it is larger than the arrangement width W1. For the same reason, it is desirable that the thickness W2 of the soft magnetic rotator 10 is also equal to or larger than the arrangement width W1, and the magnetic sensing surfaces of the first SV-GMR element MR1 to the fourth SV-GMR element MR4 are the outer periphery of the soft magnetic rotator 10. It is desirable to be in the same plane parallel to the plane that touches the surface.

  The outer peripheral surface of the soft magnetic rotator 10 is from each of the top portions 13a to 13f having a maximum distance from the rotation center O, the minimum portions 14a to 14f having a minimum distance from the rotation center O, and the top portions 13a to 13f. It has 1st surface 11a-11f extended to the rotation direction front side, and 2nd surface 12a-12f extended to the rotation direction back side from each of the top parts 13a-13f. The top portions 13a to 13f are formed at equiangular intervals (every 60 ° in the figure), and are at a distance r1 from the rotation center O, respectively. The minimal portions 14a to 14f are formed at equiangular intervals (every 60 ° in the figure) and are at a distance of r2 from the rotation center O (r1> r2). Each of the first surfaces 11a to 11f is a flat surface and has the same shape. Each of the second surfaces 12a to 12f is a curved surface that protrudes outward from the outer peripheral surface, and has the same shape. Each of the minimal parts 14a to 14f exists between adjacent top parts (between the top parts 13a-13b, between the top parts 13b-13c,..., Between the top parts 13f-13a). In the first surfaces 11a to 11f, the distance from the rotation center O monotonously increases from the edges (minimum portions 14f, 14a, ..., 14e) opposite to the top portions 13a to 13f toward the top portions 13a to 13f ( The rate of change is positive. In the second surfaces 12a to 12f, the distance from the rotation center O monotonously decreases (the rate of change is negative) from the top portions 13a to 13f toward the edges (minimum portions 14a to 14f) opposite to the top portions 13a to 13f. Each of the minimum portions 14a to 14f is a boundary between the first surface 11b and the second surface 12a, a boundary between the first surface 11c and the second surface 12b, ..., the first surface 11a and the second surface. A bent portion is located at the boundary of 12f.

  An angle θ1 (θ1> 0) formed by the first surfaces 11a to 11f with respect to the rotation center O is smaller than an angle θ2 formed by the second surfaces 12a to 12f with respect to the rotation center O. That is, the distance between the front and rear edges of the first surfaces 11a to 11f (between the minimum portion 14f and the top portion 13a, between the minimum portion 14a and the top portion 13b,..., Between the minimum portion 14e and the top portion 13f). Is the distance between the front and rear edges of the second surfaces 12a to 12f (between the top 13a and the minimum 14a, between the top 13b and the minimum 14b,..., Between the top 13f and the minimum 14f). Shorter than. Alternatively, the change rate of the distance from the rotation center O in the first surfaces 11a to 11f has a larger absolute value (steep inclination) than the change rate of the distance from the rotation center O in the second surfaces 12a to 12f.

  Hereinafter, the circuit configuration of the moving object detection apparatus 100 will be described with reference to FIG. The moving body detection device 100 includes a magnetic detection unit 120, a differential amplifier circuit 140, a Schmitt trigger circuit 160 as a rectangular wave signal generation circuit, and an output circuit 240. In this embodiment, these circuits operate with a single power supply Vcc (for example, 5 V).

  The magnetic detection unit 120 is a full-bridge (Wheatstone bridge) connection of the first SV-GMR element MR1 to the fourth SV-GMR element MR4. As described above with reference to FIG. It is arranged at a position where the magnetic field changes. The pair of the first SV-GMR element MR1 and the second SV-GMR element MR2 are connected in series between the power supply line and the ground. A pair of fourth SV-GMR element MR4 and third SV-GMR element MR3 is also connected in series between the power supply line and the ground. The detection signal Vdet of the magnetic detection unit 120 is obtained as a potential difference between the connection point of the first SV-GMR element MR1 and the second SV-GMR element MR2 and the connection point of the third SV-GMR element MR3 and the fourth SV-GMR element MR4. . The detection signal Vdet of the magnetic detection unit 120 is amplified by the differential amplifier circuit 140.

Differential amplifier circuit 140 includes resistors R3 to R6 and an operational amplifier 142. The resistors R3 and R4 are connected in series between the connection point of the third SV-GMR element MR3 and the fourth SV-GMR element MR4 and the output terminal of the operational amplifier 142. The connection point of the resistors R3 and R4 is connected to the inverting input terminal of the operational amplifier 142. The resistors R5 and R6 are connected in series between the connection point of the first SV-GMR element MR1 and the second SV-GMR element MR2 and the output terminal of the reference voltage source Vref (2.5 V). A connection point between the resistors R5 and R6 is connected to a non-inverting input terminal of the operational amplifier 142. The resistance values of the resistors R3 to R6 are R3 = R5 and R4 = R6. Therefore, the amplification degree of the differential amplifier circuit 140 is R4 / R3, and the amplified signal Vamp of the differential amplifier circuit 140 is
Vamp = − (R4 / R3) Vdet + 2.5 [V]
It is. The amplification degree may be set near 1.

  A Schmitt trigger circuit 160 as a rectangular wave signal generation circuit generates a rectangular wave signal Vrct based on the amplified signal Vamp output from the differential amplifier circuit 140. The Schmitt trigger circuit is a circuit (such as a hysteresis comparator) that switches a threshold voltage. For example, assuming that the threshold voltage of the Schmitt trigger circuit 160 is Vth1, Vth2 (Vth1> Vth2) and the current threshold voltage is Vth1, the Schmitt is performed when the amplified signal Vamp output from the differential amplifier circuit 140 exceeds Vth1. The level of the output signal of the trigger circuit 160 transitions (transition from the high level to the low level), and the threshold voltage of the Schmitt trigger circuit 160 switches from Vth1 to Vth2. In this state, when the amplified signal Vamp output from the differential amplifier circuit 140 falls below Vth2, the level of the output signal of the Schmitt trigger circuit 160 transitions (transitions from low level to high level), and the threshold voltage of the Schmitt trigger circuit 160 is Switching from Vth2 to Vth1. The difference between Vth1 and Vth2 is called the hysteresis width. The level of the output signal of the Schmitt trigger circuit 160 even if a noise component within the hysteresis width is mixed into the amplified signal Vamp after the amplified signal Vamp output from the differential amplifier circuit 140 exceeds Vth1 or falls below Vth2. Because it does not transition, it is resistant to noise.

  The rectangular wave signal Vrct output from the Schmitt trigger circuit 160 is input to the output circuit 240 and is output from the output circuit 240 as the output signal Vout. Note that the polarity of the output signal Vout is inverted from that of the rectangular wave signal Vrct. The output circuit 240 includes resistors R1 and R2 and a bipolar transistor Q. The resistor R2 is provided between the output terminal of the Schmitt trigger circuit 160 and the base of the bipolar transistor Q. The resistor R1 is provided between the power supply line and the collector of the bipolar transistor Q. The emitter of the bipolar transistor Q is grounded. The collector voltage of the bipolar transistor Q becomes the output signal Vout of the output circuit 240.

  FIG. 4A is a time chart illustrating the operation of the moving object detection apparatus 100 shown in FIGS. In this time chart, in order from the top, the distance from the rotation center of the portion of the outer peripheral surface of the soft magnetic rotator 10 located immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, the differential amplifier circuit 140 The amplified signal Vamp output from the output circuit 240 and the output signal Vout of the output circuit 240 are shown.

  When the soft magnetic rotator 10 rotates and the first surface (any one of the first surfaces 11a to 11f) approaches the first SV-GMR element MR1 to the fourth SV-GMR element MR4, each SV. The influence of the second surface (any one of the second surfaces 12a to 12f) on the bias magnetic field is small and the influence of the first surface on the bias magnetic field is large at the position of the magnetosensitive surface of the GMR element. For this reason, the magnetic body rotation tangential component of the magnetic field at the position of the magnetically sensitive surface of each SV-GMR element faces the direction in which the first surface approaches (substantially opposite to the rotation direction of the soft magnetic rotator 10). As a result, the first SV-GMR element MR1 and the third SV-GMR element MR3 have a low resistance, and the second SV-GMR element MR2 and the fourth SV-GMR element MR4 have a high resistance. As a result, the amplified signal Vamp output from the differential amplifier circuit 140 increases, and after any one of the minimum portions 14a to 14f passes immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, the amplified signal Vamp is The output signal Vout, which exceeds the upper threshold voltage Vth1 of the Schmitt trigger circuit 160 and is inverted from the rectangular wave signal Vrct output from the Schmitt trigger circuit 160, transitions from the low level to the high level (in FIG. 4A, during the period T2). End and start of period T1).

  Thereafter, when the soft magnetic rotator 10 further rotates and the top portion (any one of the top portions 13a to 13f) approaches the first SV-GMR element MR1 to the fourth SV-GMR element MR4, each SV-GMR element. The magnetic material rotation tangential component of the magnetic field at the position of the magnetosensitive surface approaches 0. Then, when the top portion passes directly above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, this time, the influence of the second surface on the bias magnetic field causes the magnetic field at each magneto-sensitive surface position of each SV-GMR element. The magnetic material rotation tangential component is directed in the direction in which the second surface moves away (substantially forward direction of the rotation direction of the soft magnetic rotator 10). As a result, the first SV-GMR element MR1 and the third SV-GMR element MR3 have a high resistance, and the second SV-GMR element MR2 and the fourth SV-GMR element MR4 have a low resistance. Then, the amplified signal Vamp output from the differential amplifier circuit 140 becomes small, and immediately after the top portions 13a to 13f pass right above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, the amplified signal Vamp is a Schmitt trigger circuit. The output signal Vout changes from a high level to a low level below the lower threshold voltage Vth2 of 160 (the end of the period T1 and the start of the period T2 in FIG. 4A).

  A comparative example will be described. FIG. 4B is a time chart illustrating the operation of the moving object detection device 800 illustrated in FIGS. 10 and 11. The circuit of the moving object detection device 800 is the same as that shown in FIG. As described above, as the soft magnetic gear 80 rotates, the magnetic rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element changes abruptly near the convex edge of the soft magnetic gear 80. However, the convex surface and the concave surface (parts forming the circumferential surface) away from the edge are close to 0 and hardly change. Therefore, as is apparent from FIG. 4B, in the case of the comparative example, the soft magnetic gear 80 is rotated immediately before the front edge of the convex portion in the rotational direction or immediately after the rear edge of the convex portion in the rotational direction. The amplified signal Vamp changes only for a very short time, and the amplified signal Vamp has the same magnitude (near 2.5 V) and hardly changes in the other portions, that is, the convex surface and the concave surface (portion forming the circumferential surface) separated from the edge.

  On the other hand, in the case of the present embodiment shown in FIG. 4A, the period in which the amplified signal Vamp is the same magnitude (near 2.5 V) and hardly changes is significantly shortened. This is because, instead of the soft magnetic gear 80 shown in FIGS. 10 and 11, the outer peripheral surface is mostly a circumferential surface, the rotational center O as shown in FIGS. This is because the soft magnetic rotating body 10 whose outer peripheral surface is constituted by the first and second surfaces whose distance from the surface increases or decreases monotonously is used. That is, since the first surface has a long period during which the magnetic material rotation tangential direction component of the magnetic field at the position of the magnetosensitive surface of each SV-GMR element is substantially opposite to the rotation direction of the soft magnetic rotator 10, the amplified signal Vamp is 2 Long period of rising off 5V. Similarly, since the second surface has a long period during which the magnetic material rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element is kept approximately in the forward direction of the rotation direction of the soft magnetic rotator 10, the amplified signal Vamp is The period of falling off 2.5V is long. Therefore, in the present embodiment, the period during which the amplified signal Vamp is separated from the vicinity of 2.5 V is significantly longer than that of the comparative example.

  The above-described differences between the present embodiment and the comparative example are particularly significant when the power is turned on. This will be described below.

  FIG. 5A is a time chart illustrating an operation at the time of power-on of the moving object detection apparatus 100 shown in FIGS. In this figure, the power is turned on when the first surface is located immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, and the threshold voltage of the Schmitt trigger circuit 160 is Vth1 when the power is turned on. Shows the case. When the power is turned on, the magnetic surface rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element is substantially opposite to the rotation direction of the soft magnetic rotating body 10 due to the action of the first surface on the bias magnetic field. Therefore, the amplified signal Vamp immediately rises and exceeds the upper threshold voltage Vth1 of the Schmitt trigger circuit 160, and the output signal Vout obtained by inverting the rectangular wave signal Vrct output from the Schmitt trigger circuit 160 is changed from the low level to the high level. Transition to. That is, in this embodiment, a rectangular wave output signal reflecting the position of the soft magnetic rotator 10 is obtained from the time of power-on.

  A comparative example will be described. FIG. 5B is a time chart illustrating the operation of the moving object detection apparatus 800 illustrated in FIGS. 10 and 11 when the power is turned on. This figure shows that the power is turned on when the circumferential surface of the convex portion is located immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, and the threshold voltage of the Schmitt trigger circuit 160 is turned on. A case of Vth1 is shown. When the power is turned on, the magnetic material rotation tangential component of the magnetic field at the position of the magnetic sensitive surface of each SV-GMR element is close to zero. Therefore, the amplified signal Vamp stays within the hysteresis width near 2.5V and does not exceed the upper threshold voltage Vth1 of the Schmitt trigger circuit 160. Therefore, the output signal Vout remains at a low level. However, when the power is turned on, that is, when the circumferential surface portion of the convex portion is located immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4, as shown in FIG. The output signal Vout is at a high level. That is, in the comparative example, when the power is turned on, a rectangular wave output signal reflecting the position of the soft magnetic gear 80 cannot be obtained.

  According to the present embodiment, the following effects can be achieved.

(1) Due to the action of the first surfaces 11a to 11f on the bias magnetic field, the magnetic material rotating tangential component of the magnetic field at the position of the magnetic sensitive surface of the first SV-GMR element MR1 to the fourth SV-GMR element MR4 It changes for a longer period in the direction opposite to the rotation direction compared to the prior art. As a result, the period during which the amplified signal Vamp output from the differential amplifier circuit 140 does not change in the vicinity of 2.5 V is shorter than that in the prior art, and the period in which the upper threshold voltage Vth1 of the Schmitt trigger circuit 160 is exceeded is increased. . That is, in the period during which the output signal Vout should output a high level (period T1 in FIG. 4A), the period during which the amplified signal Vamp exceeds the upper threshold voltage Vth1 of the Schmitt trigger circuit 160 becomes longer. For this reason, when the power is turned on in a state where the output signal Vout should output a high level, there is a high degree of certainty that the output signal Vout becomes a high level reflecting the state. Therefore, it is possible to more accurately detect the rotation information of the soft magnetic rotator 10 when the power is turned on. The effect | action with respect to the bias magnetic field by 2nd surface 12a-12f also has the same effect.

(2) As described above, the amplified signal Vamp output from the differential amplifier circuit 140 is resistant to noise because the period during which the amplified signal Vamp does not change in the vicinity of 2.5 V is shorter than that of the prior art. That is, if noise exceeding the hysteresis width of the Schmitt trigger circuit 160 is input during a period in which the amplified signal Vamp does not change around 2.5 V, there is a risk that an erroneous pulse is input to the output signal Vout. In comparison, the amplified signal Vamp has a short period in which it does not change in the vicinity of 2.5 V, so that such a risk is reduced.

(3) The angle θ1 formed by the first surfaces 11a to 11f with the rotation center O is smaller than the angle θ2 formed by the second surfaces 12a to 12f with the rotation center O, and the first surfaces 11a to 13f are positioned at both sides. Changes in the distance from the rotation center O of the surfaces 11a to 11f of the first surface 11a to 11f are steeper than those of the second surfaces 12a to 12f. For this reason, the level of the output signal Vout can be reliably shifted in the very vicinity where the top portions 13a to 13f pass directly above the first SV-GMR element MR1 to the fourth SV-GMR element MR4. Therefore, the position detection accuracy of the soft magnetic rotator 10 is high.

(4) Since the first surfaces 11a to 11f are flat surfaces, processing is easy. In addition, since the second surfaces 12a to 12f are curved surfaces that protrude outwardly from the outer peripheral surface, the position of the magnetic sensitive surface of each SV-GMR element is higher than that of a curved surface that protrudes outward from the flat surface or outer peripheral surface. It is convenient that the period during which the magnetic material rotation tangential component of the magnetic field in FIG.

(Second Embodiment)
In the present embodiment, the shape of the soft magnetic rotator in the first embodiment is slightly changed, and other configurations are the same as those in the first embodiment.

  FIG. 6 is an exemplary schematic perspective view of a moving object detection apparatus 200 according to the second embodiment of the present invention. FIG. 7 is a front view of the moving object detection apparatus 200 shown in FIG. In these drawings, the shape of the soft magnetic rotator 20 is different from the shape of the soft magnetic rotator 10 shown in FIGS. 1 and 2. Hereinafter, this point will be mainly described.

  The outer peripheral surface of the soft magnetic rotator 20 has a top 23a to 23f at which the distance from the rotation center O is maximum, and the adjacent tops (between the tops 23a-23b, between the tops 23b-23c,..., The top 23f- 23a), and the first surface extending from the top portions 23a to 23f to the front side in the rotational direction from the deep portions 24a to 24f having a maximum depth based on the plane passing through the adjacent top portions. 21a to 21f and second surfaces 22a to 22f extending from the top portions 23a to 23f to the rear side in the rotation direction. The top portions 23a to 23f are formed at equiangular intervals (every 60 ° in the figure), and are at a distance r1 from the rotation center O, respectively. The extreme deep portions 24a to 24f are formed at equal angular intervals (every 60 ° in the figure), and are at a distance of r2 from the rotation center O (r1> r2). The first surfaces 21a to 21f are flat surfaces and have the same shape. The second surfaces 22a to 22f are also flat and have the same shape. In 1st surface 21a-21f, the top part (top part 23f-23a, top part) which adjoins toward the top parts 23a-23f from the edge (extreme deep part 24f, 24a, ..., 24e) opposite to the top parts 23a-23f. 23a-23b,..., The depth based on the plane passing through the tops 23e-23f) monotonously decreases (change rate is negative). In the second surfaces 22a to 22f, the top portions (top portions 23a-23b, top portions 23b-23c,...) From the top portions 23a to 23f toward the edges opposite to the top portions 23a to 23f (extremely deep portions 24a to 24f). The depth based on the plane passing through the tops 23f-23a) monotonously increases (the rate of change is positive). Each of the extreme deep portions 24a to 24f is a boundary between the first surface 21b and the second surface 22a, a boundary between the first surface 21c and the second surface 22b, ..., the first surface 21a and the second surface 22a. A bent portion is located at the boundary of the surface 22f.

  An angle θ1 (θ1> 0) formed by the first surfaces 21a to 21f with respect to the rotation center O is smaller than an angle θ2 formed by the second surfaces 22a to 22f with respect to the rotation center O. That is, between the front-side and rear-side edges of the first surfaces 21a to 21f (between the extreme deep part 24f and the top part 23a, between the extreme deep part 24a and the top part 23b,..., Between the extreme deep part 24e and the top part 23f. ) Is the distance between the front and rear edges of the second surfaces 22a to 22f (between the top 23a and the deep part 24a, between the top 23b and the deep part 24b,..., The top 23f and the deep part). Shorter than the distance between the portions 24f). Alternatively, the depth change rate of the first surfaces 21a to 21f has a larger absolute value (steep slope) than the depth change rate of the second surfaces 22a to 22f.

  The operation and effect of the moving object detection device 200 of this embodiment are substantially the same as those of the moving object detection device 100 of the first embodiment. However, since the second surfaces 22a to 22f are flat in the present embodiment, each SV is compared with the first embodiment in which the second surface is a curved surface that protrudes outward from the outer peripheral surface. It can be said to be slightly disadvantageous in that the period during which the magnetic body rotation tangential component of the magnetic field at the position of the magnetosensitive surface of the GMR element is kept approximately in the forward direction of the rotation direction of the soft magnetic rotor 20 is shortened. However, since the second surface is not a curved surface but a flat surface, it is advantageous in terms of ease of processing.

(Third embodiment)
In the present embodiment, the techniques of the first and second embodiments are applied to position detection of a soft magnetic linear moving body.

  FIG. 8 is an exemplary schematic perspective view of a moving object detection apparatus 300 according to the third embodiment of the present invention. FIG. 9 is a front view of the moving object detection apparatus 300 shown in FIG. In these drawings, a soft magnetic linear moving body 30 is used in place of the soft magnetic rotating body 10 shown in FIGS. Hereinafter, the shape of the soft magnetic linear moving body 30 will be mainly described.

  The soft magnetic linear moving body 30 as the magnetic material linear moving body is attached to a linear moving portion in a machine tool (not shown), for example. The soft magnetic linear moving body 30 has a plate shape or a column shape, and has an uneven surface (lower surface in the figure). The concavo-convex surface has a top portion 33a to 33d having a maximum height in the convex direction (hereinafter simply referred to as “height”), and between adjacent top portions (between the top portions 33a and 33b and between the top portions 33b and 33c). Between the top portions 33d to 33d), the minimum portions 34a to 34d having a minimum height, the first surfaces 31a to 31d extending from the top portions 33a to 33d to the front side in the moving direction, and the top portions 33a to 33d. Second surfaces 32a to 32d extending rearward in the movement direction from each of 33d. The height of the top portions 33a to 33d is h1, and the height of the minimal portions 34a to 34d is h2 (h1> h2). The first surfaces 31a to 31d are flat surfaces and have the same shape. The second surfaces 32a to 32d are also flat and have the same shape. In the first surfaces 31a to 31d, the height monotonously increases from the edges opposite to the top portions 33a to 33d (end portion 34x, minimum portions 34a to 34c) toward the top portions 33a to 33d (change rate is positive). In the second surfaces 32a to 32d, the height monotonously decreases from the top portions 33a to 33d toward the edges (minimum portions 34a to 34d) opposite to the top portions 33a to 33d (change rate is negative). Each of the minimum portions 34a to 34d is located at the boundary between the first surface 31b and the second surface 32a, the boundary between the first surface 31c and the second surface 32b, and the boundary between the first surface 31d and the second surface 32c. It is located and becomes a bent part. The same applies when the number of tops is greater than in the illustrated case.

  Distance between the front and rear edges of each of the first surfaces 31a to 31d (between the end 34x and the top 33a, between the minimum 34a and the top 33b,..., Between the minimum 34c and the top 33d) Is between the front and rear edges of each of the second surfaces 32a to 32d (between the top 33a and the minimum part 34a, between the top 33b and the minimum part 34b,..., Between the top 33d and the minimum part 34d). Shorter than the distance. Alternatively, the height change rate of the first surfaces 31a to 31d has a larger absolute value (steep slope) than the height change rate of the second surfaces 32a to 32d.

  The operation of the moving body detection device 300 of the present embodiment is substantially the same as that of the moving body detection device 100 of the first embodiment except that the detection target is changed from a rotating body to a linear moving body. The point that the position information of the soft magnetic linear moving body 30 when the power is turned on can be accurately detected and the point that it is resistant to noise are the same as in the first embodiment (effects (1) and (1) of the first embodiment). 2)). In the present embodiment, the distance between the front and rear edges of each of the first surfaces 31a to 31d is greater than the distance between the front and rear edges of each of the second surfaces 32a to 32d. It is shortened. Therefore, the level of the output signal Vout can be reliably shifted in the very vicinity where the top portions 33a to 33d pass immediately above the first SV-GMR element MR1 to the fourth SV-GMR element MR4. Therefore, the position detection accuracy of the soft magnetic linear moving body 30 is high. Further, since both the first and second surfaces are flat, processing is easy.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  The number of top portions in the embodiment is an example, and the number of top portions may be increased or decreased in a modification. For example, any number of 1 or more may be used in the first embodiment, any number of 3 or more in the second embodiment, or any number of 2 or more in the third embodiment. The number of tops may be appropriately determined according to the required accuracy and application.

  In the embodiment, a plurality of top portions are formed at equal intervals. However, in a modification, the intervals may be different for each pair of adjacent top portions. When the intervals are made different, the plurality of first surfaces are made different shapes and the plurality of second surfaces are made different shapes (changing the distance between both edges). The interval at which the top portion is formed may be determined according to the application.

  In the first embodiment, the first surface is a flat surface, but in a modified example, it may be a curved surface (concave curved surface) that is convex on the inner peripheral surface instead. In the third embodiment, the first and second surfaces are flat surfaces. However, in the modified example, the first surface is a curved surface (that is, a concave curved surface) that is convex in the negative height direction. The second surface may be a curved surface that is convex in the positive direction of the height (that is, a convex curved surface).

  In the first and second embodiments, the rotation direction of the soft magnetic rotator is counterclockwise as shown in FIGS. 2 and 7, but in the modification, the rotation direction of the soft magnetic rotator is reversed (FIG. 2). And clockwise in FIG. 7). Also in this case, the rotation information of the soft magnetic rotator when the power is turned on can be accurately detected as compared with the prior art, and it is also resistant to noise. The same applies to the third embodiment, and the moving direction of the soft magnetic linear moving body may be the right direction instead of the left direction shown in FIG.

  In the embodiment, the SV-GMR element is full-bridge connected, but the connection form of the SV-GMR element is not limited to this, and may be a half-bridge connection. Although full-bridge connection is superior in terms of magnetic detection sensitivity and temperature characteristics, in the case of half-bridge connection, the number of components can be reduced because only two SV-GMR elements are required. Further, it is possible to form a half bridge with the SV-GMR element and a fixed resistor. In this case, although the magnetic detection sensitivity is lower than that in the case where the half bridge is formed by two SV-GMR elements, the cost can be reduced. The same applies to the full-bridge connection. Instead of forming a full bridge with four SV-GMR elements, a full bridge may be formed with two SV-GMR elements and two fixed resistors.

  In the embodiment, the case where the moving body detection device is driven by a single power source has been described as an example. However, the present invention is not limited to this. In the case of dual power supply driving, the reference voltage source Vref (2.5 V) is unnecessary and can be replaced with ground.

  In the embodiment, the magnetic field generating means is a permanent magnet. However, an electromagnet may be used on the principle of operation.

1 is an exemplary schematic perspective view of a mobile object detection device according to a first exemplary embodiment of the present invention. It is a front view of the moving body detection apparatus shown by FIG. It is a circuit diagram of the moving body detection apparatus shown by FIG. (A) is a time chart illustrating the operation of the mobile body detection device shown in FIGS. 1 to 3, and (B) is a time chart illustrating the operation of the mobile body detection device shown in FIGS. 10 and 11. is there. (A) is a time chart illustrating the operation when the mobile object detection device shown in FIGS. 1 to 3 is turned on, and (B) is when the mobile object detection device shown in FIGS. 10 and 11 is turned on. It is a time chart which illustrates the operation | movement of. It is an exemplary schematic perspective view of the moving body detection apparatus which concerns on the 2nd Embodiment of this invention. It is a front view of the moving body detection apparatus shown by FIG. It is an exemplary schematic perspective view of the moving body detection apparatus which concerns on the 3rd Embodiment of this invention. It is a front view of the moving body detection apparatus shown by FIG. It is an exemplary schematic perspective view of the moving body detection apparatus described in Patent Document 1. It is a front view of the soft magnetic gear shown in FIG. It is explanatory drawing of the fundamental structure and magnetic characteristic of a SV-GMR element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Soft magnetic rotating body 11a-11f 1st surface 12a-12f 2nd surface 13a-13f Top part 14a-14f Minimal part 50 Bias magnet 100 Moving body detection apparatus MR1-MR4 1st-4th SV-GMR element

Claims (8)

A magnetic material including a magnetic material rotating body, a bias magnetic field generating means, and at least one spin-valve giant magnetoresistive element fixed to the bias magnetic field generating means so as to face the outer peripheral surface of the magnetic material rotating body. A detection unit and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit, A moving body detection device for detecting rotation information;
The outer peripheral surface of the magnetic material rotating body is:
A top portion at which the distance from the rotation center of the magnetic material rotating body is maximized;
A minimal portion where the distance from the rotation center of the magnetic material rotating body is minimal;
A first surface extending forward from the top in the rotational direction;
A second surface extending from the top to the rear side in the rotational direction,
In the first surface, the distance from the rotation center monotonously increases from the edge opposite to the top toward the top.
In the second surface, the distance from the rotation center monotonously decreases from the top toward the edge opposite to the top.
The moving body detecting apparatus according to claim 1, wherein an edge of the first and second surfaces opposite to the top portion is located at the minimum portion, and the same number of the minimum portions as the top portion is present.   2. The moving body detection apparatus according to claim 1, wherein there are a plurality of the top portions, the first surface extends from each of the plurality of top portions in a rotation direction front side, and the second surface is the plurality of top portions. A moving body detection apparatus, wherein the moving body detection apparatus extends rearward in the rotation direction.   3. The moving body detection apparatus according to claim 1, wherein the first surface is a flat surface, the second surface is a curved surface protruding outward from the outer peripheral surface, and the minimal portion is a bent portion. A moving body detection apparatus characterized by comprising: A magnetic material including a magnetic material rotating body, a bias magnetic field generating means, and at least one spin-valve giant magnetoresistive element fixed to the bias magnetic field generating means so as to face the outer peripheral surface of the magnetic material rotating body. A detection unit and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit, A moving body detection device for detecting rotation information;
The outer peripheral surface of the magnetic material rotating body is:
A plurality of top portions having a maximum distance from the rotation center of the magnetic material rotating body;
There is only one location between adjacent top portions, and the deep portion where the depth based on the plane passing through the adjacent top portions is maximum,
A first surface extending from each top to the front side in the rotational direction;
A second surface extending from each top to the rear side in the rotational direction,
In the first surface, the depth monotonously decreases from the edge opposite to the top to the top.
In the second surface, the depth monotonously increases from the tops toward the edges opposite to the tops,
An edge of the first and second surfaces opposite to the tops is located at the extreme deep part.   5. The moving body detection apparatus according to claim 4, wherein the first and second surfaces are flat surfaces, and the extreme deep portion is a bent portion.   6. The moving body detection device according to claim 1, wherein an angle formed by the first surface with respect to a rotation center of the magnetic material rotating body is such that the second surface is the magnetic material rotating body. A moving body detection apparatus characterized by being smaller than an angle formed with respect to a rotation center. Magnetic material linear moving body having an uneven surface, bias magnetic field generating means, and at least one spin valve type fixedly disposed to the bias magnetic field generating means so as to face the uneven surface of the magnetic material linear moving body A magnetic detection unit including a giant magnetoresistive element and a rectangular wave signal generation circuit that generates a rectangular wave signal based on an output signal of the magnetic detection unit, and based on the rectangular wave signal generated by the rectangular wave signal generation circuit A moving body detecting device for detecting position information of the magnetic material linear moving body,
The uneven surface of the magnetic material linear moving body is:
A plurality of tops where the height is maximum,
There is only one place between the adjacent tops, and the minimum part has a minimum height,
A first surface extending from the top to the front side in the movement direction;
A second surface extending from each top to the rear side in the moving direction,
In the first surface, the height increases monotonously from the edge opposite to the top to the top.
In the second surface, the height decreases monotonously from each top to the edge opposite to each top,
The moving body detecting apparatus, wherein the minimal portion is located at an edge opposite to the top portions of the first and second surfaces.   The moving body detection apparatus according to claim 7, wherein a distance between front and rear edges of the first surface in a moving direction is shorter than a distance between front and rear edges of the second surface in the moving direction. A moving body detection apparatus characterized by that.

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