JPH1123724A - Sensor for ferromagnetic object transit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand the degree of freedom of design such as the arrangement allowance range of a magnetism-sensing element by detecting a magnetic field in nearly vertical direction for a magnetization direction between a permanent magnet and a ferromagnetic body in the magnetism-sensing element for detecting a magnetic field in a direction that is in parallel with an element surface. SOLUTION: A ferromagnetic body transit sensor comprises a holder part 3 with a through hole 4 where, for example, a ferromagnetic ball that is a specimen can pass through, a permanent magnet 1 with approximately 3,000-4,000 Gauss surface magnetic flux density, and a magnetism-sensing element 2 that is formed by a thin film such as NiFe with a magnetism-sensing element surface 6 for detecting a horizontal magnetic field. And, the permanent magnet 1 is arranged so that is arranged so that it is at right angle to a straight line for connecting the center of a magnetic pole surface and that of a hole 4, while the magnetism-sensing element is arranged so that the center of the element surface 6 faces the side of the hole 4 at a point where the center of the element surface 6 deviates from the straight line. It is suitable that the magnetism-sensing element 2 and the permanent magnet 1 are provided on the front and rear surfaces of a substrate 7. When a magnetic ball is not in the hole 4, the magnetic field cannot be detected. Otherwise, a magnetic field Hx is generated for detecting, thus detecting a passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventional techniques similar to the present invention include, for example, Japanese Patent Application Laid-Open Nos.
As described in Japanese Patent Publication No. 1998875, there is known a metal sphere detecting device using a Hall element for detecting a magnetic field perpendicular to an element surface.

FIG. 11 is a diagram showing a configuration of a metal sphere detecting device described in the above publication. In the figure, a metal sphere detecting device includes a holder 30 having a through hole 40 through which a metal sphere 50 passes, a permanent magnet 10 and a Hall element 60 held by the holder 30, and a strong element provided between them. It is constituted by an L-shaped magnetic path 70 made of a magnetic material.

The metal sphere 5 when passing through the magnetic pole surface of the permanent magnet 10, the element surface of the Hall element 60, and the through hole 40.
The position of the metal sphere 5 is set so that the magnetic pole surface and the element surface are perpendicular to the radial direction from the center of the metal sphere 50.
0.

As described above, the metal sphere detecting device described in the above publication uses a Hall element which is a magnetic sensing element for detecting a magnetic flux perpendicular to the element surface. Is extremely restricted. That is, the permanent magnet surface and the Hall element surface are set at 9
It is necessary to arrange them at an angle of about 0 ° or 90 ° × N (N is a natural number). Also in the case of FIG. 11, the magneto-sensitive surface of the element is configured so that the tangential direction of the sphere, that is, the angle between the radius and the magneto-sensitive surface of the element is perpendicular. Further, since the Hall element itself does not exhibit good linearity (linearity) output characteristics with respect to an external magnetic field under a small magnetic field, the magnetic force of the permanent magnet is increased, or the permanent magnet-magnetic sensing element sandwiching a ferromagnetic sphere is used. The air gap between them needs to be set very small.

Further, a ferromagnetic object passage sensor using a horizontal magnetic field sensing element for detecting a magnetic field in a direction of the element surface provided with a magnetoresistive element or the like of a ferromagnetic thin film on the element surface provided with the magnetoresistive element is disclosed in the present application. Before the filing of the application (Japanese Patent Application No. 9-496)
No. 15).

The ferromagnetic object passage sensor detects the magnetic field distribution in a direction substantially coincident with a magnetic pole direction generated in a permanent magnet and a ferromagnetic object passing in the vicinity of the permanent magnet.
In one embodiment, the magnetic sensing element detects a magnetic flux line on a long magnetic path side generated by the permanent magnet and the ferromagnetic object in the passing part. Since the magneto-sensitive element has a characteristic of operating even with a small magnetic field, a malfunction may be induced by an external leakage magnetic field or an intentionally applied magnetic field. .

[0008]

In a conventional ferromagnetic sphere detecting device, an element such as a Hall element which detects a vertical magnetic field on an element surface is operated at a maximum value of the magnetic field intensity generated from a permanent magnet. Therefore, it is necessary to set the angle between the detection element surface and the center point of the magnetic sphere at a specific angle of about 90 ° (angle α). As long as a vertical magnetic sensing element such as a Hall element is used, the degree of design freedom between the components of the ferromagnetic sphere passage sensor, ie, the permanent magnet, the sphere passage hole, and the detection element is extremely reduced. The Hall element is 3
For weak magnetic fields such as 0 Gauss or less, good linearity characteristics as shown under a strong magnetic field cannot be obtained.
It is extremely difficult to perform a switching operation in the presence or absence of a magnetic field in only one of the pole and the N pole. Therefore, it is necessary to increase the magnetic force of the permanent magnet or to set the air gap between the permanent magnet, the sphere, and the detection element to be very narrow, so that the sphere to be passed is easily attracted by the permanent magnet.

In a ferromagnetic object passing sensor using a magneto-sensitive element having a magneto-resistive element of a ferromagnetic thin film on the element surface, the magneto-sensitive element operates on a very small magnetic field.
A malfunction may be induced by an external leakage magnetic field or an intentionally applied magnetic field.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to widely set the mutual positional relationship between a permanent magnet, a magnetic sensing element, and a passage portion of a ferromagnetic object, thereby greatly improving the degree of freedom in design and assembly. It is in.

Another object of the present invention is to reduce the size of the entire ferromagnetic object passage sensor.

Another object of the present invention is to use a horizontal magnetic field sensing element so as not to cause a malfunction due to an external leakage magnetic field or an intentionally applied magnetic field. Is to suppress.

[0013]

A ferromagnetic object passage sensor according to the present invention is a ferromagnetic object passage sensor for detecting the passage of a ferromagnetic object by a permanent magnet and a magneto-sensitive element. An element that detects a magnetic field in the horizontal (parallel) direction with respect to the element surface (the surface on which the magnetically sensitive material is provided), and is substantially perpendicular to the magnetic pole direction between the permanent magnet and a ferromagnetic object passing in the vicinity of the permanent magnet. The permanent magnet, the magneto-sensitive element, and the passing portion of the ferromagnetic object are disposed so as to detect the magnetic field distribution of the magnetic field.

Further, the sensor for passing a ferromagnetic object according to the present invention comprises:
A substrate, a magneto-sensitive element for detecting a magnetic field in a horizontal direction with respect to the element surface, the element surface being attached to one surface of the substrate substantially parallel, and a permanent magnet having a magnetic pole surface attached substantially parallel to the other surface of the substrate. And a magnet.

The permanent magnet in the ferromagnetic object passing sensor is a strong magnet having a surface magnetic flux density of 3,000 gauss or more, and the magneto-sensitive element is made of Ni-Fe, Ni-Co or Ni-Fe-Co. It is characterized by being formed of any one of the thin films.

(Function) The magneto-sensitive element is biased in a saturation region by a magnetic field component substantially parallel to the magnetic pole surface generated on the magnetic pole surface of the permanent magnet itself in a state where the ferromagnetic object does not exist. The ferromagnetic object is detected by switching from the saturated region to the non-saturated region due to a change in the direction of the magnetic field line during the passage.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a ferromagnetic object passage sensor according to the present invention.

Referring to FIG. 1, this embodiment has a holder portion 3 having a through hole 4 through which a sphere can pass, and is attached to the holder portion 3 and preferably has a surface magnetic flux density of 3,000 to 4, A magnetosensitive element 2 having a permanent magnet 1 having a magnetization strength of about 000 gauss and a magnetosensitive element surface (element surface) 6 provided with a magnetoresistive material for detecting magnetism and capable of detecting a horizontal magnetic field, for example, in a different direction A exhibiting the magnetoresistance effect
It is composed of an MR (Anisotropic Magneto resistace Element) element or an element obtained by combining a pulse shaping circuit with the AMR element.

Here, the arrangement relationship between the through hole 4, the permanent magnet 1, and the magneto-sensitive element 2 in the holder portion 3 is such that the magnetic pole surface of the permanent magnet 1 is located at the center of the magnetic pole surface and at the center of the through hole 4. The magneto-sensitive element 2 is disposed on the substrate 7 so that the element surface 6 faces upward on the upper surface side of the permanent magnet 1. In addition, in order to improve the accuracy of the positional relationship between the magneto-sensitive element and the permanent magnet, it is preferable that both are integrally provided on the front and back surfaces of the substrate 7 as shown in the embodiments described later.

In the structure shown in FIG. 1, the magneto-sensitive element 2 is such that the center of the element surface 6 is in contact with the center of the magnetic pole face and the through hole 4.
Is mounted so as to be located at a point deviated to the right from the straight line connecting to the center of the. This is because the magneto-sensitive element 2 cannot detect a magnetic field in the vertical direction.

FIG. 2 is a schematic diagram showing the distribution of the magnetic force lines 9 generated by the permanent magnets when the magnetic sphere 5 passes through the through-hole portion 4 and when the magnetic sphere 5 does not pass.

In a state where the magnetic sphere 5 passes through the through hole 4, as shown in FIG. 2A, the permanent magnet 1 and the magnetic sphere 5 approaching the permanent magnet 1 Magnetic poles N and S are generated. The feature of the magnetic field distribution in this case is
Lines of magnetic force are concentrated between the magnetic sphere 5 and the permanent magnet 1 in the upward direction. Since the lines of magnetic force are perpendicular to the magneto-sensitive element surface 6, the magneto-sensitive element cannot detect this magnetic field.

Before and after the passage of the magnetic sphere 5, the lines of magnetic force 9 have a distribution of lines of magnetic force between the magnetic poles N and S of the permanent magnet 1 alone, and a curve is drawn above the permanent magnet 1 as shown in FIG. Therefore, a magnetic field component Hx in the element surface direction is generated near the upper surface of the permanent magnet 1. In this state, the magneto-sensitive element detects the magnetic field component Hx and changes the output.

FIGS. 3 (a) and 3 (b) show the results of computer analysis of the magnetic field line distribution of the permanent magnet alone and the magnetic field line distribution when the permanent magnet and the ferromagnetic object are adjacent to each other by the finite element method. . It can be seen that the distribution forms are almost identical to those of FIGS. 2A and 2B schematically drawn.

FIG. 4 is a view showing another embodiment in which the arrangement position of the magnetic sensing element in the ferromagnetic object passage sensor according to the present invention is changed. FIG. 4A shows an arrangement relationship between the through hole 4 on the holder 3 and the permanent magnet 1 which is the same as that of FIG. 1 except that the magneto-sensitive element 2 is opposite to the straight line near the upper surface of the permanent magnet 1. It is shifted in the direction. FIG. 4B shows that the position of the permanent magnet 1 is a position at which the angle between the pole face of the permanent magnet and a straight line connecting the center of the magnet and the center of the through hole 4 is shifted from a right angle. The element 2 is arranged such that the element surface 6 is located substantially on the straight line. 4C, the arrangement relationship between the through hole 4 and the permanent magnet 1 is substantially the same as that of FIG. 4B, and the magneto-sensitive element 2 is located at a point where the element surface 6 is shifted from the straight line. It is arranged so that.

The sensor for passing a ferromagnetic object of the present invention is basically of a type in which a horizontal magnetic field detecting element detects a magnetic field component in a direction parallel to a magnetic pole surface of a permanent magnet in a state where no ferromagnetic sphere is present. The magnetic element surface does not need to face the magnetic object, and the passage of a sphere can be detected only by disposing the magneto-sensitive element surface at a position where a magnetic field component in a direction parallel to the magnetic pole surface can be detected. .

Therefore, an appropriate positional relationship other than the positional relationship shown in FIG. 4 can be selected and set.
For example, in addition to FIG. 4, the relative position of both the magneto-sensitive element and the permanent magnet and the mutual positional relationship with respect to the through hole 4 may be shifted left and right and back and forth (in the thickness direction of the holder 3). The distance D can be appropriately changed.
Further, the angle α between the element surface of the magneto-sensitive element and the straight line connecting the center point of the magneto-sensitive element and the center point of the through hole can be changed as appropriate, and can be set to any angle other than 90 °. it can. It is not always necessary that the magnetic pole surface of the permanent magnet and the magneto-sensitive element surface of the magneto-sensitive element are parallel.

Next, the characteristics of the magneto-sensitive element applied to the present embodiment and the operation using the magneto-sensitive element will be described.

The magneto-sensitive element 2 changes its electric resistance value in accordance with a magnetic field component horizontal (parallel) to the element surface. The resistance value R per single element is as follows:
It changes according to the signal magnetic field Hx.

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

The magneto-sensitive element is positioned relative to the permanent magnet and the sphere (through hole) so that the resistance of the magneto-sensitive element changes effectively depending on the strength of the magnetic field in the Hx direction shown in the magnetic field distribution of FIG. The relationship is determined, and when the magnetic field in the Hx direction is strengthened, the magnetic field is detected and the output signal of the magneto-sensitive element is increased, and conversely, it is decreased when weakened. Permalloy (Ni-Fe), Ni-Co, or a Ni-Fe-Co alloy is used as a magnetoresistive material of the magneto-sensitive element having such characteristics.

FIG. 5A shows the magnetic field saturation characteristics of the magneto-sensitive element of this embodiment. Magnetic field intensity is weak magnetic field X
It shows a characteristic that it completely saturates at 3 or more and generates a Y6 level magnetic field detection output.

In the present embodiment, the magnetic field lines which draw a curve from the magnetic pole surface of the permanent magnet in a state where the ferromagnetic object does not pass through the through hole are detected based on the characteristics of the magnetic sensing element. That is, the magnetic field Hx in the direction parallel to the pole face
And operates to output the voltage of the saturation characteristic. When the ferromagnetic object passes through the through-hole, strong magnetic lines of force are generated perpendicular to the element surface of the magneto-sensitive element from the magnetic pole surface of the permanent magnet. Never show.

Therefore, in the normal state where the ferromagnetic object does not pass through the through hole, the magneto-sensitive element is in a state where a magnetic bias is applied to the saturation region by the magnetic field Hx of the permanent magnet adjacent to the lower part. Therefore, it is possible to increase a noise margin with respect to an external magnetic field, and to prevent malfunction due to intentional application of a magnetic field or the like. In addition, in a normal state where the ferromagnetic object does not pass, the magneto-sensitive element does not detect the application of a magnetic field that causes pseudo passage of the ferromagnetic object from the through hole direction.

As the magnetic sensing element used in the present embodiment, it is preferable to use, for example, an integrated magnetic sensing element having a switching characteristic with respect to a magnetic field as described in Japanese Patent Publication No. 7-78528. The magnetic sensing element described in the publication is configured as two or four elements, or as a composite element of these elements and an integrated circuit (IC) as required.

FIG. 6A shows one side 3 of the integrated magnetic sensing element described in the above-mentioned publication in which the magnetic sensing element is integrated with an IC.
FIG. 3 is a diagram showing a specific structure of a terminal configuration. As shown in the figure, the magneto-sensitive element is formed by patterning a thin film of a magnetic resistor using a ferromagnetic material into a predetermined shape on the element surface. Usually, the magnetic resistor is divided into four parts and arranged and connected to form a bridge. Also,
The thin films of the magneto-sensitive element are formed on a base of an integrated circuit of the waveform shaping circuit and are electrically wired to each other so that a change in the resistance value of the magneto-sensitive element is output as a pulse voltage.

FIG. 6B is a diagram showing an equivalent circuit of the pulse waveform shaping circuit itself. Power supply terminals 17 and 19 are connected to a bridge composed of the magnetic resistors 11 to 14. The output at the center of the bridge is connected to a comparator 15 having a feedback resistor 16 for giving a hysteresis characteristic. Is output. Here, the resistance value of one (for example, 11) of the magnetic resistances constituting the bridge is set to a small value in advance. With the above configuration, the output voltage becomes “0” (Hig) due to the passage of the ferromagnetic object.
h) → "1" (Low) → "0" (High).

In this embodiment, by using such an integrated magnetic sensing element, the function of preventing malfunction due to magnetic disturbance and noise can be further improved due to hysteresis characteristics.

The permanent magnet of the present embodiment preferably has a surface magnetic flux density of 3,000 to 4,000 gauss. By using such a permanent magnet, it is possible to reliably generate a magnetic field in the Hx direction sufficient to generate a detection output on the magnetosensitive surface near the upper surface of the permanent magnet in a state where no ferromagnetic object is present, The air gap between the permanent magnet and the magneto-sensitive element, or the constraint on the mounting accuracy, has a margin, and the assembly accuracy of the sensor can be reduced. This is because a horizontal magnetic field sensing element can be used as the sensing element and its magnetic field saturation characteristics can be used.

That is, as shown in FIG. 5 (a), the characteristics of the magneto-sensitive element of the present invention are almost saturated by a magnetic field intensity of X3 or more, and the combination of the magneto-sensitive element of the present invention and a permanent magnet This is because the magnetic sensing element can be partially biased to a saturation characteristic. On the other hand, those using a perpendicular magnetic field sensing element such as a Hall element as in the conventional example are:
Since the output varies in proportion to the magnetic field strength as shown in FIG. 5B, the effect of the mounting position of the element is large, and the threshold value can be set even by using a comparator circuit as shown in FIG. Difficult, and as a result, the magnetic field strength from the permanent magnet to the element surface is limited to a narrow range.

As described above, in the present invention, it is sufficient that the condition for obtaining a magnetic field of a certain level or more with respect to the magneto-sensitive element is satisfied.
Since there are few restrictions, the mounting margin of the permanent magnet and the magneto-sensitive element is allowed in a very wide range.

[0042]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 7 is a diagram illustrating the configuration of the present embodiment. FIG. 7A is a view seen from the upper surface side of the holder, and FIG. 7B is a perspective view seen from the lower right side surface of the holder.

The holder portion 3 is provided with a groove 8 extending from the vicinity of the through hole 4 to the end of the holder, and the substrate 7 is provided near the through hole 4 of the groove 8 on the side of the through hole 4 of the substrate 7. A magneto-sensitive element 2 having an element surface substantially parallel to the surface and detecting a magnetic field in a horizontal direction with respect to the element surface;
A ferromagnetic object sensor block provided integrally with a permanent magnet 1 having a magnetic pole surface mounted substantially parallel to the surface opposite to the through hole 4 is adopted.

In this embodiment, a sphere having a diameter of 11 mm and a magnet having a surface magnetic flux density of 3,000
A permanent magnet of 0 to 4,000 gauss is used. As a magnetic sensing element (magnetic field detection sensor) for sensing a surface magnetic field at a position where a space gap is 0.5 to 1.0 mm, an MRSM76 or MRSS95 (NEC) having the configuration of FIG.
And the through-hole does not completely face the element surface (the magnetoresistive element portions 11 to 14 in FIG. 6B), and the angle α is an appropriate angle other than 90 °. Like that. The reason for excluding 90 ° here is 90 °
In this case, the difference in output of the magneto-sensitive element between the passage and non-passage of the ferromagnetic object is minimized.

FIG. 8A is a diagram showing a magnetic field-output characteristic using an integrated MR sensor of a magnetic sensing element as shown in FIG. In FIG. 8A, the magnetic field strength is normalized and displayed, but the integrated MR sensor normally operates with a small magnetic field of tens of gauss. However, by arranging the magnetic sensor close to the permanent magnet as in the present embodiment, a magnetic bias is always applied to the magneto-sensitive element, so that it responds to an external noise magnetic field which is not a magnetic field to be detected originally. It is possible to increase the threshold so as not to do so. That is, by applying a magnetic bias to the magneto-sensitive element 2 in the arrangement shown in FIG. 8C, the hysteresis characteristic of the magneto-sensitive element alone can be changed from the threshold values (H ₁ , H ₂ ) in FIG. ) Thresholds (H ₁ ′, H ₂ ′) to improve the noise margin by setting the high level V _H state when the ferromagnetic object is not passing and the low level V _L state when the ferromagnetic object is passing. Let me.

FIGS. 8C and 8D show external magnetic field sources 5.
FIG. 4 is a diagram for explaining the effect of the magneto-sensitive element on the magneto-sensitive element with respect to 0. For example, when the magneto-sensitive element 2 is combined with the permanent magnet 1 in the configuration shown in FIG. H sensitive element 1 to ₂ or more field operates, whereas the erroneously detected as passing ferromagnetic object, Figure 8 of the arrangement of this embodiment of FIG. 8 from the outside even without this (a) ( c)
According to this, by arranging a permanent magnet near the back of the magneto-sensitive element, the sensitivity to an external magnetic field can be improved to about H ₂ ′ = 5 * H ₂ , and erroneous detection operation can be prevented. Become like In this embodiment, in the initial state where no magnetic object is present, the permanent magnet 1
The output voltage level for giving a strong magnetic field is at a high level V _H, but only to a low level V _L when ferromagnetic objects passing, not only on the circuit design problems logic level is inverted.

FIG. 9 shows an output waveform and an example of signal processing of the ferromagnetic object passage sensor according to this embodiment. The output of the magneto-sensitive element 1 is fixed at a high level V _H by the magnetic field of the biasing permanent magnet 1 when no ferromagnetic object is present. Further, when a ferromagnetic object passes, the direction changes in the direction of the line of magnetic force, the horizontal magnetic field sensing element operates, and the output voltage changes to the low level _VL only during the passage. The digital output of the magneto-sensitive element is integrated by a counting circuit such as a counter IC or the like, and is displayed on a display unit.

FIG. 10 is a diagram showing changes in the distribution of the lines of magnetic force when the shape of the magnetic pole surface of the permanent magnet is formed as a flat surface and a curved surface. Depending on the arrangement of the through hole and the permanent magnet, the magnetization strength of the permanent magnet, and the like, the ferromagnetic object may be attracted to the permanent magnet when passing through the through hole. It is necessary to take measures to prevent this. It may be. In particular, the permanent magnet is very strong and
When the position of the permanent magnet is very close to that of the through hole due to the structural design, the magnetic pole surface of the permanent magnet 1 is made convex (spherical or cylindrical side) as shown in FIG. This has the effect of preventing the magnetic object from being pulled by the magnetic force of the permanent magnet and hindering passage through the through-hole portion.

In the above-described embodiment, a sphere is described as the ferromagnetic object. However, the detected ferromagnetic object does not necessarily have to be a sphere, but the magnetic field distribution of the permanent magnet alone and the permanent magnet and the magnetic pole If the magnetic field distribution of the ferromagnetic object in which the magnetic field occurs has the above-mentioned tendency, the ferromagnetic object of any shape can be analyzed and measured based on the above-described configuration and principle. The ferromagnetic object passage sensor according to the invention can be configured.

In the embodiment, only the element having the AMR effect has been described as the magneto-sensitive element of the horizontal magnetic field.
(Giant Magneto Resistance) and C
MR (Colossal Magneto Resistance)
It is also possible to use an element having an effect.

[0051]

According to the sensor for passing a ferromagnetic object of the present invention, the use of the magnetic field detecting element in the direction (element surface) horizontal to the element surface of the magneto-sensitive element restricts the arrangement of the magneto-sensitive element. Since the number is reduced, the permissible range of the arrangement position of the magneto-sensitive element with respect to the passage position of the ferromagnetic sphere or the like can be widened, and the design margin can be significantly increased.

Further, a horizontal magneto-sensitive element exhibiting high sensitivity to a minute magnetic field is used, and a single magnetic field component of a permanent magnet and a magnetic field component generated by the permanent magnet and a ferromagnetic object are used as a detection magnetic field. Therefore, it is possible to widen a mounting margin and a selection range of the permanent magnet, the through hole, and the magneto-sensitive element.

In particular, since a permanent magnet is arranged close to the magneto-sensitive element and a magnetic field bias is applied to the magneto-sensitive element, a malfunction due to noise or intentional application of a magnetic field from the outside can be prevented. .

[0054]

[Brief description of the drawings]

FIG. 1 is a top view showing an embodiment of a ferromagnetic object passage sensor according to the present invention.

FIG. 2 is a diagram showing the presence or absence of a ferromagnetic sphere and a change in the direction of magnetic field lines created by a permanent magnet with the presence of the ferromagnetic sphere.

FIG. 3 is a diagram showing an example in which the distribution of lines of magnetic force between a permanent magnet and a ferromagnetic sphere is calculated.

FIG. 4 is a top view showing another embodiment of the ferromagnetic object passage sensor according to the present invention.

FIG. 5 is a diagram showing output characteristics with respect to the magnetic field intensity of the magneto-sensitive element.

FIG. 6 is a perspective view of the integrated magnetic sensing element formed on the integrated circuit board after mold sealing and a diagram showing an example of an equivalent circuit of the integrated circuit.

FIG. 7 is a top view and an oblique side view showing one embodiment of the present invention.

FIG. 8 is a diagram illustrating a different arrangement relationship between a horizontal magnetic field sensing element and a permanent magnet and a comparison of sensitivity to an external magnetic field.

FIG. 9 is a diagram showing an output waveform and signal processing of the ferromagnetic object passage sensor according to the present invention.

FIG. 10 is a diagram showing a distribution of lines of magnetic force generated between a form of a magnetic pole surface of a permanent magnet and a ferromagnetic sphere.

FIG. 11 is a view showing a conventional metal ball detecting device.

[Explanation of symbols]

 1, 10, 70 Permanent magnet 2 Horizontal magnetic field sensing element 3, 30 Holder with through hole 4, 40 Through hole 6 Element surface 7 Substrate 8 Groove 9 Line of magnetic force 5, 50 Ferromagnetic sphere 11 to 14 Bridge circuit Magnetic sensing element 15 Comparator 16 Feedback resistor 17, 19 Power supply terminal 18 Output terminal 20 Horizontal magnetic sensing element 60 Vertical magnetic sensing element (Hall element)

Claims (7)

[Claims] 1. A ferromagnetic object passage 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 an element surface, The passing portion of the permanent magnet, the magnetic sensing element and the ferromagnetic object so as to detect a magnetic field distribution in a direction substantially coincident with a direction parallel to the magnetic pole surface of the permanent magnet between the magnet and the ferromagnetic object passing therethrough. A ferromagnetic object passage sensor, which is provided. 2. A straight line passing through the center of the element surface of the magneto-sensitive element and the center point of the passing ferromagnetic object has an angle of 90 ° or less with the element surface of the magneto-sensitive element. Item 1
The sensor for passing a ferromagnetic object according to claim 1. 3. A substrate, a magneto-sensitive element for detecting a magnetic field in a horizontal direction with respect to the element surface, the element surface being attached to one surface of the substrate in substantially parallel, and a magnetic pole surface being substantially provided on the other surface of the substrate. A ferromagnetic object passage sensor, comprising: a permanent magnet mounted in parallel. 4. The permanent magnet and the magneto-sensitive element are positioned such that the center of the pole face of the permanent magnet does not coincide with the center of the element surface of the magneto-sensitive element. The sensor for passing a ferromagnetic object according to claim 1. 5. The permanent magnet has a surface magnetic flux density of 3,0.
5. The ferromagnetic object passage sensor according to claim 1, wherein the sensor is a strong magnet of at least 00 Gauss. 6. The magnetic sensing element is made of Ni—Fe, Ni—C.
The ferromagnetic object passage sensor according to claim 1, 2, 3, 4, or 5, wherein the sensor is formed of a thin film of either o or Ni-Fe-Co. 7. The magnetic sensing element may be composed of Ni—Fe, Ni—C
A thin film of either o or Ni-Fe-Co is formed on a silicon substrate of a semiconductor integrated circuit, and the magneto-sensitive element and the semiconductor integrated circuit are electrically connected to be configured as an integrated magneto-sensitive element. The method according to claim 1, 2, 3, 4, or 5.
The sensor for passing a ferromagnetic object according to claim 1.