JPH1167034A - Sensor for detecting passing of ferromagnetic article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widely set the positional relationship between a permanent magnet and a magneto-sensitive element so as to remarkably increase the degrees of freedom of design and assembly by setting, out of a specific value, an angle formed between a straight line passing the center of a surface of the magneto- sensitive element and the center of a passing orbit of a ferromagnetic object and the surface of the magneto-sensitive element. SOLUTION: A sensor for detecting passing of a ferromagnetic article comprises a holder having a through hole 4, through which a ferromagnetic object 5 passes, and a permanent magnet 1 and a magneto-sensitive element 2 which are fixed to the holder. The magneto-sensitive element 2 is formed of an element capable of detecting a fine magnetic field in a horizontal direction with respect to the surface of the element with high sensitivity, e.g. an AMR element capable of exhibiting an anisotropic magnetic resistance effect. Consequently, it becomes unnecessary to set to 90 deg. an angle α between a straight line L passing the center O of a passing orbit of the ferromagnetic object 5 and the center of the surface of the magneto-sensitive element 2 and the surface of the magneto-sensing element 2; namely, it is sufficient that α≠90 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting the passage of a ferromagnetic object, and more particularly to a sensor for detecting passage of a ferromagnetic object.
The present invention relates to a sensor for detecting the passage of a ferromagnetic object using an element for detecting a magnetic field in a direction horizontal to the element surface (magnetically sensitive surface) as a magneto-sensitive element.

[0002]

2. Description of the Related Art Conventionally, as a sensor for detecting passage of a ferromagnetic object, for example, a metal sphere detecting device disclosed in Japanese Patent Application Laid-Open No. 60-102585 (Document 1) and Japanese Patent Application Laid-Open No. 61-199875 (Document 2) has been known. It has been known. FIG. 14 shows a main part of the metal sphere detecting device. The metal sphere detecting device includes a holder 30 having a through hole 40 through which a metal sphere 50 passes, and a permanent magnet 1 attached to the holder 30.
0 and a Hall element 60, and L made of a ferromagnetic material constituting a magnetic circuit connecting the permanent magnet 10 and the Hall element 60.
And a magnetic path 70 in the shape of a letter.

[0003] The pole face of the permanent magnet 10 and the Hall element 6
The positional relationship between the element surface of 0 (magnetic sensing surface) and the metal sphere 50 when passing through the through-hole 40 is such that the magnetic pole surface of the permanent magnet 10 and the element surface of the Hall element 60 are at the center of the metal sphere 50, that is, the metal sphere 50. The center of the passing locus is perpendicular to the center O (α = 90 °, β =
90 °). In this metal sphere detecting device, the magnetic flux perpendicular to the element surface of the Hall element 60 is detected, and the passage of the metal sphere 50 is detected.

[0004]

However, according to such a conventional metal sphere detecting device, it is necessary to design the device to operate at the maximum value of the magnetic field intensity generated from the permanent magnet 10. It is necessary to set the angle α between the straight line L passing through the center O of the trajectory of the sphere 50 and the center of the element surface of the Hall element 60 and the element surface of the Hall element 60 to a specific angle of 90 °. As described above, as long as an element that detects a perpendicular magnetic field to the element surface, such as a Hall element, is used as the magneto-sensitive element, the arrangement relationship between the permanent magnet, the sphere passage hole, and the magneto-sensitive element is extremely limited, and the inter-component The degree of freedom in design is extremely reduced.

Further, the Hall element cannot obtain a characteristic with good linearity as shown under a strong magnetic field for a weak magnetic field of 30 Gauss or less. It is extremely difficult to perform a switch operation for presence or absence. Therefore, in FIG. 14, it is necessary to increase the magnetic force of the permanent magnet 10 or to set the air gap between the permanent magnet 10, the metal sphere 50, and the Hall element 60 very narrow. For this reason, the metal sphere 50 to be passed is easily attracted by the permanent magnet 10.

The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to set a relative positional relationship between a permanent magnet and a magneto-sensitive element in a wide range and to design freely. To provide a ferromagnetic object passage detection sensor capable of greatly improving the degree of freedom and assembly flexibility, enabling the use of low-magnetism permanent magnets or small-sized permanent magnets, and realizing cost reduction and miniaturization. It is in.

[0007]

In order to achieve the above object, a first invention (the invention according to claim 1) is to provide a magneto-sensitive element with an element for detecting a magnetic field in a horizontal direction with respect to the element surface. The angle α between a straight line passing through the center of the element surface of the magneto-sensitive element and the center of the locus of passage of the ferromagnetic object and the element surface of the magneto-sensitive element is α {90 °. According to the invention,
The passage of a ferromagnetic object is detected by a magneto-sensitive element arranged as α {90} based on a magnetic field acting horizontally on the element surface.

In a second invention (an invention according to claim 2), the magneto-sensitive element is an element for detecting a magnetic field in a horizontal direction with respect to the element surface, and the magneto-sensitive element and the permanent magnet pass through a ferromagnetic object. An acute angle side between the straight line passing through the center of the element surface of the magneto-sensitive element and the center of the path of the passage of the ferromagnetic object and the element surface of the magneto-sensitive element. Angle α
Is set to 42 ° ≦ α ≦ 80 °. According to the present invention, based on the magnetic field distribution in a direction almost coincident with the magnetic pole direction generated in the ferromagnetic object passing through the permanent magnet and the vicinity thereof by the magneto-sensitive element arranged as 42 ° ≦ α ≦ 80 °,
The passage of a ferromagnetic object is detected.

According to a third aspect of the present invention, the magneto-sensitive element is an element for detecting a magnetic field in a horizontal direction with respect to the element surface, and a center of the element surface of the magneto-sensitive element and a ferromagnetic object. The angle α between the straight line passing through the center of the passing locus and the element surface of the magneto-sensitive element is α ≠ 90 °, and a permanent magnet is arranged on the back of the magneto-sensitive element. According to the present invention, the passage of a ferromagnetic object is detected by the magneto-sensitive element arranged as α {90} based on the presence or absence of a horizontal magnetic field acting on the element surface.

The fourth invention (the invention according to claim 4) is the first invention.
In the third invention, an integrated MR (Magn)
eto Resistance Element) sensor. According to the present invention, for example, MR manufactured by NEC Corporation
The passage of a ferromagnetic object is detected by SM76 or MRSS95.

The fifth invention (the invention according to claim 5) is the first invention.
In the fourth to fourth inventions, the magneto-sensitive element has an element pattern formed of a thin film of Ni-Fe, Ni-Co, or Ni-Fe-Co. According to the present invention, Ni—Fe (permalloy) or Ni—C
The passage of a ferromagnetic object is detected by the magneto-sensitive element in which the element pattern is formed by o or a thin film of Ni-Fe-Co alloy.

The sixth invention (the invention according to claim 6) is the first invention.
In the fifth to fifth inventions, the magnetic pole surface of the permanent magnet is a convex curved surface. According to the present invention, the amount of magnetic flux toward the ferromagnetic object is dispersed, and the ferromagnetic material is less likely to be attracted to the permanent magnet.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. Embodiment 1 FIG. 1 is a perspective view showing a main part of a sensor for detecting passage of a ferromagnetic object according to the present invention. The ferromagnetic object passage detection sensor 100 includes a holder unit 3 having a through hole 4 through which a ferromagnetic sphere (for example, a pachinko ball) 5 passes.
And the permanent magnet 1 and the magneto-sensitive element 2 attached to the holder 3.

The permanent magnet 1 has a surface magnetic flux density of 100
A magnet having a magnetization amount of about 0 to 2000 Gauss and capable of obtaining a magnetic force of 20 to 30 Gauss as a minimum in a specific direction at a position separated by several mm is used. The magneto-sensitive element 2 is an element capable of detecting a weak magnetic field in a horizontal direction with respect to the element surface with high sensitivity, for example, an AMR (An Isotropic Magneto Resistan) exhibiting an anisotropic magnetoresistance effect.
ce Element: An anisotropic magneto-resistance element) or an element obtained by combining a pulse shaping circuit with the AMR element is used.

The magneto-sensitive element 2 has a rectangular parallelepiped shape as shown in an enlarged view of FIG.
It is possible to form an element surface (magnetically sensitive surface) on any of the surfaces. In this embodiment, for example, the 2B surface is the element surface. Further, as shown in FIG. 3A, an angle α formed between a straight line L passing through the center O of the locus of passage of the ferromagnetic sphere 5 and the center of the element surface of the magnetosensitive element 2 and the element surface of the magnetosensitive element 2 Is α ≠
90 °. That is, in this embodiment,
Since an element for detecting a horizontal magnetic field is used as the magneto-sensitive element 2, it is not necessary to set α to {90}. In this case, the angle β formed by the center of the magnetic pole surface of the permanent magnet 1 and the center of the element surface of the magneto-sensitive element 2 with respect to the center O of the passage locus of the ferromagnetic sphere 5 is β = α. It should be noted that β = α is not an essential requirement, and some ± is allowed.

FIG. 4 is a schematic diagram showing a magnetic field line distribution when the ferromagnetic sphere 5 passes through the through hole 4. As shown in the drawing, the magnetic poles (S, N) are generated in the ferromagnetic sphere 5 by the permanent magnet 1 and the ferromagnetic sphere 5 approaching the permanent magnet. The characteristic of the magnetic field line distribution generated by this is that the magnetic field lines 6 generated from the magnetic pole N of the ferromagnetic sphere 5 to the magnetic pole S of the ferromagnetic sphere 5
And the magnetic force lines 7 generated from the intermediate portion of the ferromagnetic sphere 5 toward the magnetic pole S of the permanent magnet 1.

In this embodiment, the magnetic field detected by the magneto-sensitive element 2 is not the magnetic field line distribution in the A direction but the magnetic field line distribution substantially in the B direction composed of the magnetic field lines 6 and 7 in the magnetic field line distribution in FIG. is there. The magneto-sensitive element 2 detects the generation of the magnetic field in the B direction and outputs the detected magnetic field as passing through the ferromagnetic sphere 5.

That is, in this embodiment, basically, a magnetic field (horizontal magnetic field) is generated in the direction of the magnetic pole between the N pole (S pole) of the permanent magnet 1 and the ferromagnetic sphere 5 on which the magnetic pole appears. ), It is not necessary to set α = 90 °, and only the element surface of the magneto-sensitive element 2 is arranged at a position where the B-direction magnetic field component can be detected. Passage can be detected.

FIG. 5A is a diagram showing the intensity of the magnetic field at the moment when the ferromagnetic sphere 5 passes through the through hole 4 and before and after the passage. In FIG. 5A, the horizontal axis (X axis) represents the distance in the B direction with reference to the center position 0x of the ferromagnetic sphere 5 (see FIG. 5B), and the vertical axis (Y axis) is the magnetic field strength. Is represented. The characteristic I indicated by a solid line indicates the magnetic field intensity at the moment when the ferromagnetic sphere 5 passes through the through hole 4, and the characteristic II indicated by the dotted line indicates each magnetic field intensity before or after the ferromagnetic sphere 5 passes.

The magnetic field strength of the characteristic I is -6x (FIG. 5 (b)
The maximum value is shown at -6x, and the minimum value is shown at 0x, from the leftmost position of the ferromagnetic sphere 5 shown in FIG. The magnetic field strength before and after passing through the ferromagnetic sphere 5 is -6x to -2x of the characteristics I and II.
As can be seen from the region of FIG.

Note that the magnetic field tends to gradually increase from 0x to + 4x toward the right end of the ferromagnetic sphere 5.
As will be described later, when the magnetic force of the permanent magnet 1 is strong, the characteristics are similar to those on the 0x to -6x side.

The magneto-sensitive element 2 is constituted as a two-element element, a four-element element, or a composite element of these elements and an integrated circuit (IC) as required. In the magneto-sensitive element 2, the electric resistance value changes according to the magnetic field component in the horizontal direction with respect to the element surface. The resistance value R per single element is given by the following equation, and changes according to the signal magnetic field Hx.

R = R ₀ + ΔRMAX {1− (Hx / H ₀ ) ² } where R ₀ is the initial resistance value, ΔRMAX is the maximum change amount of the resistance value, and H ₀ is the saturation magnetic field of the element in the hard axis direction. H ₀ = 4πMt / W + Hk {W: width of element pattern (magnetic sensing pattern), t: film thickness, M: saturation magnetization, Hk: anisotropic magnetic field}.

The magneto-sensitive element 2 is connected to the permanent magnet 1 and the passing ferromagnetic sphere 5 so that the resistance value of the element pattern changes effectively depending on the strength of the magnetic field in the B direction shown in the magnetic field distribution of FIG. The relative relationship is determined, and the output signal of the magneto-sensitive element 2 increases when the magnetic field in the B direction increases,
Conversely, when it weakens, it becomes smaller. As the magnetic sensing element 2, for example, Japanese Patent Publication No. 7-078528 (Document 3)
It is preferable to use a magneto-sensitive element having switching characteristics with respect to a magnetic field as described in (1).

FIG. 6 shows an example of a magneto-sensitive element 2 'configured as a composite element with an integrated circuit. In FIG. 6, reference numeral 20 denotes an integrated circuit board, reference numerals 31 and 33 denote power terminals, and reference numeral 32 denotes output terminals, which are sealed with a mold. On the integrated circuit substrate 20, an element pattern is formed by patterning a thin film of a magnetoresistive element using a ferromagnetic material into a predetermined shape. Usually, the element pattern is divided into four and arranged and connected to form a bridge. The bridge is connected to the integrated circuit board 2 so that the resistance change is output as a pulse voltage.
It is electrically connected to the waveform shaping circuit built on the zero.

FIG. 7 is a diagram showing an equivalent circuit of the magneto-sensitive element 2 '. Power supply terminals 31 and 33 are connected to a bridge composed of the element patterns 11 to 14. The output at the center of the bridge is connected to a comparator 21 having a feedback resistor 22 for giving a hysteresis characteristic. Is output. With this configuration, it is possible to obtain a magneto-sensitive switch in which the output voltage changes from “0” level (“L” level) to “1” level (“H” level) by passing through the ferromagnetic sphere.

[Angular Range of α] Referring to FIG. 5, if the radius of the sphere is R, the X axis is 5.5x = R, and the Y axis is 6y.
= 30G. When the ferromagnetic sphere 5 passes near the permanent magnet 1, the magnetic field intensity in the B direction (X-axis direction) is within the range of -2x to -6x when the ferromagnetic sphere 5 is not present. Much larger than If the range from −2x to −6x is indicated by the angle α shown in FIG. 3A, the range is 42 ° ≦ α ≦ 80 °. In the present embodiment, α = tan ⁻¹ (R / 4) is set.

The magneto-sensitive element 2 has an element pattern of Ni
-Formed by a thin film of Fe (permalloy), Ni-Co, or a Ni-Fe-Co alloy. Also,
In order to make the detection output a digital voltage, the pulse shaping circuit shown in FIG. 7 is adopted, and the resistance value of one of the element patterns constituting the bridge (the element pattern 11 in this example) is set to the above-mentioned value. It is set small in advance as described in Reference 3. Under the above conditions, 42 ゜ ≦ α
Within the range of ≦ 80 °, only when the ferromagnetic sphere 5 passes through the through hole 4, the output of the magneto-sensitive element 2 is “1”.
Obtain a level voltage signal.

FIG. 8A shows a permanent magnet 1, a magnetic sensing element 2 and a ferromagnetic sphere 5 in this ferromagnetic sphere passage detection sensor.
It is a conceptual diagram of the relationship of. The ferromagnetic sphere 5 has a diameter of 11
mm sphere is used. As the permanent magnet 1, a permanent magnet having a surface magnetic flux density of 1000 to 2000 G is used. Magnetic sensing element 2
For example, MRSM76 or MRS95 manufactured by NEC Corporation, which detects a horizontal magnetic field at a position where the space gap is 0.5 to 1.0, is used.

The center of the element surface of the magneto-sensitive element 2 is within a range of 0.5 to 1.0 mm from the outer surface of the ferromagnetic sphere 5 and within a range of 42 ° ≦ α ≦ 80 ° (see FIG. 9). (Within the range SA shown in black). In particular, in the graph of the magnetic field strength distribution shown in FIG. 5A, it is effective to dispose the coordinates at a position shifted in the (-) direction so that -4x = 4 mm. As a result, as shown in FIG. 8B, a ferromagnetic object passing sensor 100 whose output voltage becomes “1” level when passing through the ferromagnetic sphere 5 is obtained.

FIG. 10 is a block diagram of a ferromagnetic sphere counting and displaying system. In this counting display system, the pulse voltage output output from the ferromagnetic object passage sensor 100 is counted by the counter IC 200, and the integrated value is displayed on the display unit 300.

In the embodiment described above, the ferromagnetic object is limited to a sphere, but it is not necessarily a sphere. The magnetic field distribution of the permanent magnet and the ferromagnetic object having the magnetic pole formed by the permanent magnet is as described above. If it occurs in the same direction as the magnetic pole direction, a ferromagnetic object of any shape can be analyzed and measured to form a similar ferromagnetic object passage detection sensor based on the above configuration and principle. can do.

In the above-described embodiment, FIG.
Although the case where the X coordinate in (a) is minus has been described, similar characteristics can be obtained even when the X coordinate is plus. In this case, a similar ferromagnetic object passage detection sensor can be configured by arranging the magneto-sensitive element 2 for detecting a horizontal magnetic field on the right side of the center of the ferromagnetic sphere 5.

That is, by selecting a permanent magnet having a sufficiently large surface magnetic flux density as the permanent magnet 1, FIG.
Since the increase amount and the increase tendency of the magnetic field strength on the right side of 0x on the X coordinate shown in (a) have the same characteristics as the characteristics on the left side of 0x, under such conditions, the position of the permanent magnet 1 is kept as it is and the magnetic sensitivity is maintained. The element 2 can be configured to be arranged on the right side of the center O of the locus of passage of the ferromagnetic sphere 5.

In this case, as shown in FIG. 3 (b), a straight line L passing through the center O of the passing trajectory of the ferromagnetic sphere 5 and the center of the element surface of the magneto-sensitive element 2 and the element surface of the magneto-sensitive element 2 Needless to say, the angle α on the acute angle side is set to 42 ° ≦ α ≦ 80 °. In this case, the angle β between the center of the magnetic pole surface of the permanent magnet 1 and the center of the element surface of the magneto-sensitive element 2 with respect to the center point O of the ferromagnetic sphere 5 is β = 180 ° −α. Note that β
= 180 ° -α is not an indispensable requirement, and some ± is allowed.

In the above-described embodiment, only the element having the AMR effect has been described.
to Resistance) and CMR (Colossal Magneto Resis)
It is also possible to use elements having a (tance) effect.

[Embodiment 2] In this embodiment 2,
As shown in FIG. 11A, the permanent magnet 1 is arranged on the back of the magneto-sensitive element 2. Also in this case, the angle α formed by the straight line L passing through the center O of the passage locus of the ferromagnetic sphere 5 and the center of the element surface of the magneto-sensitive element 2 and the element surface of the magneto-sensitive element 2 is α ≠ 90 °.

FIG. 12 shows a ferromagnetic sphere 5 near the permanent magnet 1.
Shows the results of computer simulation (finite element method) of the magnetic field line distribution in the absence and presence of. FIG. 12A shows a distribution when the ferromagnetic sphere 5 does not exist, and FIG. 12B shows a magnetic field line distribution when the ferromagnetic sphere 5 exists or passes. Pay particular attention to the magnetic flux lines on the side of the passing portion of the ferromagnetic sphere 5. In FIG. 12A, the magnetic force lines are distributed in a curved shape, whereas in FIG. It can be seen that the lines of magnetic force are directed upward.

That is, when the ferromagnetic spheres 5 are present, as shown in FIG. 11B, a substantially linear magnetic force line distribution from the magnetic pole surface of the permanent magnet 1 toward the ferromagnetic spheres 5 is obtained. Occurs. In this case, most of the lines of magnetic force are directed upward in the drawing, that is, in a direction perpendicular to the element surface of the magnetosensitive element 2, so that the output of the magnetosensitive element 2 is in the OFF state (Vout = Vout = Vout = Vout = Vout = Vout = Vout = Vout = Vout).
L).

On the other hand, when the ferromagnetic sphere 5 does not exist, a curved magnetic force line distribution is generated from the pole face of the permanent magnet 1 to the through hole 4 as shown in FIG. As a result, a magnetic field component in the Hx direction shown in the drawing is generated. It is possible to adjust Hx at this time so as to be the operating magnetic field of the magneto-sensitive element 2 by a method described in Document 3 or the like. The magneto-sensitive element 2 detects a magnetic field component in the Hx direction that is stronger than the predetermined value Hop, and changes its output to the ON state (Vout).
= VH).

In each of the embodiments described above, a permanent magnet having a flat magnetic pole surface is used as the permanent magnet 1, but a permanent magnet having a convex curved surface may be used. In other words, when the sensor for detecting passage of a ferromagnetic object according to the present invention is constructed, it is more effective to operate with a more stable and strong magnetic field, thereby increasing the assembly margin and improving the yield in the production of products. For this reason, it is usual to try to make the permanent magnet 1 as close as possible to the through hole 4 through which the ferromagnetic sphere 5 passes. In this case, if the magnetic pole surface portion of the permanent magnet 1 is a flat surface as shown in FIG. 13A, almost all the magnetic flux generated from the magnetic pole surface goes to the ferromagnetic sphere 5.
The ferromagnetic sphere 5 is attracted to the permanent magnet 1 and may be attracted in extreme cases. On the other hand, FIG.
If the surface is curved as shown in FIG. 3B, the amount of magnetic flux directed to the ferromagnetic sphere 5 is dispersed, and it is difficult for the permanent magnet 1 to attract the magnetic flux.

[0042]

As is apparent from the above description, according to the present invention, the use of the magneto-sensitive element for detecting the magnetic field in the horizontal direction with respect to the element surface reduces the restriction on the arrangement of the magneto-sensitive element. Therefore, the permissible range of the arrangement position of the magneto-sensitive element with respect to the passing position of the ferromagnetic object can be widened, and the mutual positional relationship between the permanent magnet and the magneto-sensitive element can be set broadly. The use of a horizontal magnetic field type magneto-sensitive element that greatly improves the degree of freedom and exhibits high sensitivity to weak magnetic fields enables the use of low-magnetism permanent magnets or small permanent magnets, resulting in cost reduction and miniaturization. It can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a ferromagnetic object passage detection sensor (first embodiment) according to the present invention.

FIG. 2 is an enlarged view of a magnetic sensing element used in the sensor for detecting passage of a ferromagnetic object.

FIG. 3 is a plan view showing an arrangement relationship between a permanent magnet and a magnetic sensing element of the sensor for detecting passage of a ferromagnetic object.

FIG. 4 is a schematic view showing a magnetic field line distribution when a ferromagnetic sphere passes through a through hole.

FIG. 5 is a diagram illustrating the intensity of a magnetic field at the moment when a ferromagnetic sphere passes through a through hole and before and after the passage.

FIG. 6 is a diagram illustrating a magnetic sensing element configured as a composite element with an integrated circuit.

FIG. 7 is a diagram showing an equivalent circuit of the magneto-sensitive element shown in FIG.

FIG. 8 is a diagram conceptually showing a relationship between a permanent magnet, a magnetic sensing element, and a ferromagnetic sphere and a sensor output voltage in the first embodiment.

FIG. 9 is a diagram showing an arrangement range of a center of an element surface of a magneto-sensitive element.

FIG. 10 is a block diagram of a ferromagnetic sphere counting and displaying system.

FIG. 11 is a diagram illustrating a second embodiment (Embodiment 2) of the ferromagnetic object passage detection sensor according to the present invention.

FIG. 12 is a diagram illustrating a computer simulation result (finite element method) of a magnetic field line distribution when a ferromagnetic sphere does not exist near a permanent magnet and when a ferromagnetic sphere exists.

FIG. 13 is a diagram comparing the directions of magnetic field lines directed to the ferromagnetic sphere when the magnetic pole surface on the side corresponding to the ferromagnetic sphere of the permanent magnet is a flat surface and when the magnetic pole surface is a convex curved surface.

FIG. 14 is a diagram showing a main part of a conventional metal ball detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Permanent magnet, 2 ... Magnetic sensing element, 3 ... Holder, 4 ... Through hole, 5 ... Ferromagnetic sphere, 6, 7 ... Magnetic force line, 100 ... Ferromagnetic object passing sensor.

Claims (6)

[Claims] 1. A ferromagnetic object passage detection sensor for detecting the passage of a ferromagnetic object by a permanent magnet and a magneto-sensitive element, wherein the magneto-sensitive element is an element for detecting a magnetic field in a horizontal direction with respect to the element surface, An angle α between a straight line passing through the center of the element surface of the magneto-sensitive element and the center of the locus of passage of the ferromagnetic object and the element surface of the magneto-sensitive element is set to α ≠ 90 °. Ferromagnetic object passage detection sensor. 2. A ferromagnetic object passage detection sensor for detecting the passage of a ferromagnetic object by a permanent magnet and a magneto-sensitive element, wherein the magneto-sensitive element is an element for detecting a magnetic field in a horizontal direction with respect to the element surface, The magneto-sensitive element and the permanent magnet are disposed at a predetermined angle from the center of the path of the ferromagnetic object, and the center of the element surface of the magneto-sensitive element and the path of the path of the ferromagnetic object. A ferromagnetic object passage detection sensor, wherein an acute angle α between a straight line passing through the center and the element surface of the magneto-sensitive element is 42 ° ≦ α ≦ 80 °. 3. A ferromagnetic object passage detection sensor for detecting passage of a ferromagnetic object by a permanent magnet and a magneto-sensitive element, wherein the magneto-sensitive element is an element for detecting a magnetic field in a horizontal direction with respect to the element surface. An angle α formed between a straight line passing through the center of the element surface of the magneto-sensitive element and the center of the locus of passage of the ferromagnetic object and the element surface of the magneto-sensitive element is set to α {90 °. Wherein the permanent magnet is disposed in the sensor. 4. The ferromagnetic object passage detection sensor according to claim 1, wherein an integrated MR sensor is used as the magneto-sensitive element. 5. The magnetic sensing element according to claim 1, wherein an element pattern of the magnetic sensing element is Ni-Fe, Ni-Fe.
A ferromagnetic object passage detection sensor formed of a thin film of any of Co and Ni-Fe-Co. 6. The ferromagnetic object passage detection sensor according to claim 1, wherein a magnetic pole surface of the permanent magnet is a convex curved surface.