JP2000018967A - Magnetic detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic detector, in which the sensitivity of a magnetic detector element is enhanced for improving the signal accuracy and reliability. SOLUTION: In the magnetic detector, comprising a magnet 103 facing a magnetic object 100 to be detected to apply a magnetic field to magnetic detecting elements 20a-d in an integrated circuit device 104 and a signal processor circuit for shaping the waveforms of analog signals which are outputted from the magnetic detecting elements 20a-d according to the movement of the magnetic object 10 to be detected, magnetosensitive faces of the magnetic detecting elements 20a-d are disposed approximately parallel with respect to the direction which faces the magnetic object 100 to be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic detection device which outputs a pulse signal according to the movement of a magnetic detection object according to a change in a gap (Gap) between the magnetic detection object and the magnetic detection device. . More specifically, it is to improve the detection accuracy of the magnetic detection device.

[0002]

2. Description of the Related Art Conventionally, a magnetic detection device for detecting movement of a magnetic object (for example, rotation of a crankshaft of an internal combustion engine) is well known. It is also known to use a giant magnetoresistive element (hereinafter, referred to as a GMR element) having higher detection sensitivity. In the following description, a conventional example using a GMR element as a magnetic detection element will be described.

In this type of magnetic detection device, a gap (Ga) between the magnetic detection object and the magnetic detection device accompanying movement of the magnetic detection object is known.
p) To output a pulse signal corresponding to the change, MR
A signal processing circuit is provided for shaping the waveform of an analog signal output from the element or the GMR element into a pulse signal.

FIG. 25 is a side view showing a magnetic detector, for example, a rotation detector, having a built-in general waveform shaping circuit. 5 schematically shows a relative positional relationship.

In FIG. 25, a magnetic object 100 to be detected is provided integrally with a rotating shaft of an internal combustion engine, for example, a crankshaft or the like.
a and the recess 100b are formed alternately. The rotation detecting device 101 is installed so as to face the magnetic detection object 100 via a predetermined gap (Gap).

FIG. 26 is a sectional view schematically showing the structure of the rotation detecting device 101 shown in FIG. In FIG. 26, a rotation detection device 101 forms a magnetic circuit by a magnetic detection head including a magnet 103 and an integrated circuit device (hereinafter, referred to as an IC) 104.

The IC 104 incorporates a GMR element and a signal processing circuit integrally, and the GMR element is arranged at a position facing the magnetic object 100. The signal processing circuit converts an analog signal obtained from the GMR element into a pulse signal and outputs the pulse signal. The magnet 103 is disposed on the back side of the IC 104, and applies a bias magnetic field to the GMR element in the IC 104.

FIG. 27 is a perspective view showing a relative positional relationship between the magnetic detection object 100 and the magnetic detection head of the rotation detecting device 101. In FIG. 27, G arranged on IC 104
The MR element 20 includes two pairs of linear segments 20a to 20d for improving the magnetic detection sensitivity and detecting the rotation direction of the magnetic object 100.

Among the segments 20a to 20d of the GMR element, a pair of segments 20a and 20b are located in front of the magnetic detection object 100 in the L rotation direction (see the arrow L rotation), and the other pair of segments 20c and 20d are It is located rearward with respect to the L rotation direction of the magnetic detection object 100.

FIG. 28 is a circuit diagram showing a connection state of each of the segments 20a to 20d constituting the GMR element 20.
In FIG. 28, each of the segments 20a to 20d constitutes two pairs of series circuits so as to mutually include one segment of each of the two pairs divided and arranged, and each series circuit includes a power supply Vcc and a ground. The bridge circuit 14 is configured by being connected in parallel between them. The midpoint 14a of the series circuit (segments 20a and 20d) in the bridge circuit 14 and the midpoint 14b of the other series circuit (segments 20c and 20b) are analog signals along with the rotation of the magnetic detection object 100. A1 and A2 are output.

FIG. 29 is a characteristic diagram showing a change in the resistance value (ohm: Ω) with respect to a change in the magnetic field (Oersted: Oe) of the GMR element. In FIG. 29, the resistance value of the GMR element fluctuates greatly when the applied magnetic field fluctuates as compared with a normal magnetoresistive element. For example, in the case of a resistance value of about 2100Ω at zero magnetic field, about 400Ω (20%
Above) The resistance value decreases. In addition, it has hysteresis in the direction in which the magnetic field is applied.

Such a GMR element is described in, for example, "Magnetoresistance effect of artificial lattice" (Journal of the Japan Society of Applied Magnetics, Vol. 15,
No. 51991, pages 813 to 821). According to the above document, the GMR element 20 can be constituted by a laminate (so-called artificial lattice film) in which magnetic layers and non-magnetic layers each having a thickness of several angstroms to several tens angstroms are alternately laminated. As the material of the GMR element 20, (Fe / Cr) n, (Permalloy / Cu / Co / Cu) n, (Co / Cu) n and the like are used. Here, n indicates the number of layers.

Next, the operation of a general rotation detecting device will be described. As shown in FIG. 27, with the rotation of the magnetic detection object 100, the convex portions 100 a and the concave portions 100 b of the magnetic detection object 100 face the magnet 103 alternately. As a result, the magnetic field applied to the GMR element 20 increases and decreases as the magnetic detection object 100 rotates. That is, the magnetic field applied to the GMR element 20 increases when the protrusion 100a approaches, and decreases when the protrusion 100a separates.

Due to the change of the magnetic flux linking the GMR element 20, the resistance of each of the segments 20a to 20d of the GMR element changes as shown in FIG. 29 according to the magnitude of the applied magnetic field. Accordingly, the midpoint voltages 14a and 14b of the bridge circuit 14 (see FIG. 28)
By the rotation of 00, analog signals A1 and A2 as shown in FIG. 30 are generated. Here, the analog signals A1, A2
In the waveform (a), a peak VH and a valley VL having a relatively large level and a sharp slope (change rate) are generated corresponding to the end of the convex portion 100a of the magnetic detection object 100.

FIG. 3 is a block diagram of an electric circuit for converting an analog signal output from the GMR element 20 into a pulse signal.
It is shown in FIG. Midpoint voltages 14a and 1 of bridge circuit 14
4b is amplified by the differential amplifier 40, and the analog signal A (= A
1-A2; see FIG. 30 (b)), AC coupling (AC coupling) is performed, and the comparator 50 outputs a binarized pulse signal by comparing with a predetermined voltage having hysteresis.

The reason why AC coupling is performed in the signal processing circuit shown in FIG. 31 is that, as shown in FIG.
This is because the DC level of the analog signal A needs to be cut to obtain a pulse signal with high accuracy because the C level changes.

Further, since the GMR element has a hysteresis, an analog signal is inverted depending on the rotation direction of the magnetic object. FIG. 33 is a diagram showing the relationship between the rotation direction of the magnetic detection object and the analog signal. For this reason, when the signal processing circuit of the DC coupling system is used, if the rotation direction of the magnetic detection object is not constant, even if the signal processing by the DC coupling is performed, the unevenness of the magnetic detection object is identified from the moment when the power is turned on. There is a problem that the AC coupling method cannot be performed.

The analog signal A shown in FIG.
There is a cross point of the ap characteristic. This cross point hardly changes after AC coupling. Therefore, in order to obtain a signal with high accuracy, it is necessary to set a comparison level at the cross point. However, since the voltage at the cross point changes depending on the shape of the magnetic object, there is a problem that the signal accuracy greatly changes depending on the shape of the magnetic object.

Further, as described above, the magnetic sensing element (GMR
Since the DC level of the analog signal A greatly changes due to a variation in the mounting position of the element) and the magnet, the signal amplification factor of the amplifier is limited, and the protrusion 10 of the magnetic detection object is restricted.
When 0a is small, the amount of change in the magnetic flux linked to the GMR element 20 is also small, and signal detection becomes impossible.

Furthermore, at high temperatures, the analog signal is halved in principle due to the temperature coefficient of resistance of the magnetic detection element (GMR element), so that the comparison voltage deviates from the Gap characteristic cross point and the temperature characteristic of signal accuracy is poor.

Further, when the analog signal A of FIG. 30 is AC-coupled, the low frequency region becomes a differential waveform shown in FIG. 34, so that an erroneous pulse is generated in the waveform shaping process. For this reason, an error occurs in the rotation speed detection in the low frequency region, and the minimum starting rotation speed increases.

Further, there are the following problems with respect to the structure of the magnetic detection device. As shown in FIG. 26, it is necessary to bend the terminal in order to avoid the magnet 103 disposed on the back side of the IC 104, so that the entire circuit including the chip component has been used in a general IC manufacturing process such as transfer molding. Cannot be packaged with a reliable sealing technology.
Therefore, only the IC part is molded and connected to the terminals by solder or the like. As a result, it is necessary to increase the number of joints and bend the IC terminals, etc., which increases the number of steps and lowers the reliability. Further, the total length of the magnetic detection device is increased by the space of the magnet.

[0023]

As described above, in the conventional magnetic detecting device, the magnetic sensing surface of the magnetic detecting element is arranged at a position sandwiched between the magnetic detection object and the magnet. Crest VH and valley V at the end of the protrusion 100a
Since only the analog signal A having L and having a cross point of the Gap characteristic at the DC level can be obtained, in order to obtain an accurate signal in combination with the most common waveform shaping processing by AC coupling, It is necessary to set hysteresis at this cross point. When the cross point of the Gap characteristic changes according to the shape of the magnetic detection object, there is a problem that the signal accuracy greatly changes.

Further, since the amplification factor of the analog signal A is regulated by the fluctuation of the DC level due to the variation of the assembling position of the magnetism detecting element (GMR element) and the magnet, when the convex portion 100a of the magnetic detection object becomes small, the GMR becomes small. The amount of change in the magnetic flux linking the element 20 is also small, and the signal cannot be detected unless the product is individually adjusted.

Further, there is a problem that the temperature characteristic of signal accuracy is poor because the analog signal is halved at a high temperature.

Since the GMR element has hysteresis as shown in FIG. 29, when the moving direction of the magnetic detection object is reversed, the analog signal A is inverted and the final output High / L
ow is also inverted. When the moving direction of the magnetic detection object is further reversed (returned to normal rotation), an erroneous pulse is output until the first unevenness change. Therefore, this erroneous pulse poses a problem when signal detection from low rotation is required.

Further, since the analog signal A has a differentiated waveform due to AC coupling in the low rotation region, there is a problem of erroneous detection as shown in FIG. 34. False pulses can also be a problem.

With respect to the structure of the magnetism detecting device, the magnet 1
Since 03 is located on the back side of the IC 104, wiring is made to the IC 104 while avoiding the magnet 103, so that the terminal shape becomes complicated. Generally, after only the IC 104 is sealed by transfer molding or the like, it is connected to a terminal by solder or the like. At this time, it is necessary to bend the terminal of the IC 104 and the number of connection points for connecting the IC 104 to the terminal is increased, so that the reliability is reduced.

Behind the magnet 103, a power supply, noise of an output terminal, and a surge protection filter circuit are provided with a chip resistor,
It is composed of a chip capacitor and the like. Since these components are connected behind the magnet 103, the overall length of the magnetic detection device is limited by the size of the magnet and the space for the electronic components.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a magnetic detection device in which the sensitivity of a magnetic detection element is improved and the detection signal accuracy and reliability are improved. I do.

[0031]

According to a first aspect of the present invention, there is provided a magnetic field generating means (magnet) disposed opposite to a magnetic object, a magnetic detecting element to which a magnetic field is applied by the magnetic field generating means, and a magnetic element. A magnetic detection device comprising a signal processing circuit for shaping the waveform of an analog signal output from a magnetic detection element in response to movement of a detection object, wherein a magnetic field generation unit responds to a change in a distance from the magnetic detection object. The magnetic sensing surface of the magnetic sensing element is arranged in a field where a change in the generated magnetic field is dominant (for example, a field in which the magnetic field does not change corresponding to the edges of the unevenness of the magnetic object).

According to a second aspect of the present invention, there is provided a magnetic field generating means arranged to face a magnetic detection object, a magnetic detection element to which a magnetic field is applied by the magnetic field generation means, and a magnetic detection element according to the movement of the magnetic detection object. A magnetic detection device including a signal processing circuit for shaping a waveform of an analog signal output from an element, wherein a magneto-sensitive surface of the magnetic detection element is arranged substantially parallel to a direction facing a magnetic detection object. It is characterized by.

According to a third aspect of the present invention, a magnetic detecting element is formed in an integrated circuit device, and a magnetic field generating means magnetized in a direction facing a magnetic detection object is provided in parallel with the integrated circuit device. Features.

According to a fourth aspect of the present invention, the magnetic field generating means is positioned and installed by transfer molding.

The invention according to claim 5 is characterized in that an AC coupling system is adopted as a waveform shaping processing system for an analog signal.

According to a sixth aspect of the present invention, the magnetic sensing element is constituted by four linear segments, each segment constituting two pairs of series circuits and each series circuit being connected in parallel to constitute a bridge circuit. Each segment has a pattern perpendicular to the direction facing the magnetic object, and two pairs of segments are arranged at a predetermined interval substantially in parallel with the facing direction.

According to a seventh aspect of the present invention, the magnetic detecting element is constituted by two linear segments, each segment is connected by a series circuit to form a bridge circuit, and each segment is opposed to the magnetic object. Is characterized by a pattern perpendicular to.

The invention according to claim 8 is characterized in that a pair of magnetic detecting elements are arranged in parallel with a predetermined interval in the moving direction of the magnetic detection object.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the pattern direction of the magnetic sensing element is formed in a direction substantially perpendicular to the direction in which the magnetic object and the magnetic field generating means face each other. .

According to a tenth aspect of the present invention, a magnetic body guide is provided at a position separated from the magnetic detection element with respect to the moving direction of the magnetic detection object.

According to an eleventh aspect of the present invention, at least a portion of the magnetic body guide is configured to be at least as high as the magnetic detecting element.

According to a twelfth aspect of the present invention, the length of the magnetic material guide is longer than the length of the magnetic field generating means.

According to a thirteenth aspect of the present invention, in the eighth aspect, the pattern direction of the magnetic detecting element is formed in a direction substantially parallel to the direction in which the magnetic object and the magnetic field generating means face each other. .

According to a fourteenth aspect of the present invention, in the thirteenth aspect, a groove is provided on a surface of the magnetic field generating means facing the magnetic detecting element in a direction parallel to a direction in which the magnetic object and the magnetic field generating means face each other. And

According to a fifteenth aspect of the present invention, the center of the magnetic detecting element is arranged at a predetermined position, for example, ± 1.5 (mm) from the end of the surface of the magnetic field generating means facing the magnetic object. It is characterized by the following.

The invention of claim 16 is characterized in that a giant magnetoresistive element is used as the magnetic detecting element.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described. FIG. 1 is a perspective view showing a magnetic detecting device according to the first embodiment, for example, a rotation detecting device, and schematically shows a relative positional relationship between the rotation detecting device 1 and a magnetic detection object 100.

In FIG. 1, a magnetic detection object 100 is provided integrally with, for example, a rotating shaft (a crankshaft or the like) of an internal combustion engine, and convex portions 100a and concave portions 100b are alternately formed on the outer peripheral portion. I have. The rotation detecting device 1 is provided from the magnetic detection object 100 via a predetermined gap (Gap), and includes a magnet 103 and an integrated circuit device (IC) 104.

The IC 104 has a built-in magnetic detection element and a signal processing circuit. In the first embodiment, an in-plane magnetoresistive element (MR element) is used as the magnetic detection element. This MR element 20 is composed of line-shaped segments 20a to 20d divided into two pairs, and as shown in FIG.
Form two pairs of series circuits, and each series circuit is connected in parallel between the power supply Vcc and the ground to form the bridge circuit 14.

In the first embodiment, the magnetic sensing surface of the MR element 20 of the IC 104 is arranged so as to be substantially parallel to the direction in which the magnetic object 100 and the magnet 103 face each other. Furthermore, although the MR element 20 has anisotropy in the magnetic sensing direction,
Here, each segment 20a, 20b and 2 of the MR element
0c and 20d are the magnetic object 100 and the magnet 1 respectively.
The pattern is perpendicular to the opposing direction of No. 03, and is arranged at a predetermined interval substantially in parallel with the opposing direction.

The magnet 103 is the MR element 2 in the IC 104
This is for applying a zero bias magnetic field, and is magnetized in a direction facing the magnetic detection object 100.

Next, the operation of the magnetic detection device according to the first embodiment will be described. With the rotation of the magnetic detection object 100, the convex portions 100a and the concave portions 100b alternately face the magnets 103, and the magnetic field applied to the MR element 20 increases and decreases with the rotation of the magnetic detection object 100. That is, the magnetic field applied to the MR element 20 increases when the protrusion 100a approaches, and decreases when the protrusion 100a separates.

Due to the change of the magnetic flux linking the MR element 20, the resistance value of each of the segments 20a to 20d of the MR element 20 changes according to the magnitude of the applied magnetic field.
Therefore, the midpoint voltage 14a of the bridge circuit 14 shown in FIG.
And 14b generate analog signals A1 and A2 by the rotation of the magnetic object 100.

FIG. 3 is a block diagram of an electric circuit for converting an analog signal output from the MR element 20 into a pulse signal. Here, the midpoint voltages 14a and 14b of the bridge circuit 14 are amplified by the differential amplifier 40 and the analog signal A
(= A1-A2).

FIG. 4 shows the relationship between the shape of the magnetic object 100 and the analog signal A. In the configuration and arrangement of the magnetic detection device (rotation detection device) 1 according to the first embodiment, the analog signal A near the edge of the convex portion 100a of the magnetic detection object 100 does not have a peak as in the related art.

Here, the reason why no peak occurs in the analog signal A will be briefly described. In the conventional example, FIG.
As shown in FIG. 3, the magneto-sensitive surfaces of the magneto-resistive elements Ra and Rb are arranged in a direction perpendicular to the direction in which the magnetic detection elements 100 are opposed to each other. It is configured to receive. That is, the magnet 103
Are drawn (concentrated) to the edge of the convex portion as the magnetic detection object 100 approaches and separates from each other, and as shown in FIG. 5C, the magnetic flux lines of the magnetic resistance elements Ra and Rb The resistance value becomes maximum and minimum at the edge, and FIG.
The output voltage of (b) results in a peak occurring near the edge of the magnetic detection object as shown in FIG.

On the other hand, in the magnetic detection device of the first embodiment,
As shown in FIGS. 7A and 7B, the magnetoresistive elements Ra and R
The magneto-sensitive surface b is arranged in a direction substantially parallel to the direction in which the magnetic object 100 is opposed to the magnetic object 100, and the magnetic field change in the direction facing the magnetic object 100 is dominant.
That is, the magnetic flux lines in the facing direction generated by the magnet 103 are
As shown in FIG. 7C, the resistance value of the magnetoresistive element Ra is not affected by the edge of the convex portion of the magnetic detection object 100, and the resistance value of the magnetoresistive element Ra is maximum corresponding to only the convex portion or concave portion of the magnetic detection object. As the analog signal that is minimized and output,
A peak near the edge of the magnetic detection object does not occur.

Further, in the magnetic detection device 1 according to the first embodiment, an analog waveform having no Gap characteristic cross point at the DC level can be obtained as shown in FIG. This analog signal does not invert the analog signal waveform corresponding to the unevenness of the magnetic object even if the rotation direction of the magnetic object 100 is reversed.
For this reason, if the waveform is shaped by the analog signal and the predetermined comparison voltage, the irregularities of the magnetic object 100 can be identified immediately after the power is turned on.

Next, the features of the structure of the magnetic detection device 1 according to the first embodiment will be described. As shown in FIG. 1, the magnet 103 for applying a bias magnetic field can be positioned parallel to the magneto-sensitive surface of the MR element 20 and can be installed on the back side of the IC 104, so that the terminal of the IC 104 can be configured flat. There is. If the terminals of the IC 104 are flat, it is possible to seal the IC 104 including the chip component with transfer molding having high reliability as a general IC sealing technique, and it is possible to improve the reliability of the product.

FIG. 8 is a sectional view showing the structure of the magnetic detection device according to the first embodiment. As shown in FIG. 8, an IC 104 having a built-in magnetic detection element and a signal processing circuit is mounted flat on a substrate, and an adhesive pedestal for the magnet 103 is formed by transfer molding technology. And signal detection accuracy is also improved.

FIG. 9 is a schematic perspective view showing an example of installation of another magnetic detection device according to the first embodiment. If the magneto-sensitive surfaces of the MR elements 20a to 20d, which are magnetic detecting elements, are arranged in a direction substantially parallel to the direction facing the magnetic detection object 100, not only the installation example of FIG. Also in the installation example, since the magnetic sensing surface of the magnetic detection element is arranged in the magnetic circuit in which the magnetic field change in the direction facing the magnetic detection object 100 is dominant, the same effects as described above can be obtained.

Embodiment 2 The analog signal A obtained by the magnetic detection device of the first embodiment is subjected to AC coupling (for example, DC component removal coupling composed of a capacitor and a resistor) to cut a DC component by a signal processing circuit shown in FIG. Then, as shown in FIG. 10, after AC coupling, the Gap characteristics cross approximately at the center of amplitude. As a result, the waveform can be accurately shaped with a general hysteresis amount (several tens of mV) regardless of the shape of the magnetic detection object 100.

Unlike the conventional device (FIG. 25), the analog signal A does not have a peak due to the edge of the convex portion.
Even if the rotation speed is low, accurate signal detection is possible without generating erroneous pulses.

Embodiment 3 In the first embodiment, an example is shown in which a magnetoresistive element (MR element) is used as a magnetic sensing element, but a giant magnetoresistive element (GMR element; Giant Magnet)
As in the first embodiment, it is also possible to detect magnetism.

In the third embodiment, as shown in FIG.
The size of the pair of GMR elements 20 is set to a width (W) of 0.3 (m).
m) × length (L) 1.35 (mm), in which two GMR films having a line width of 10 (μm) meander. G
The direction of the pattern of the MR element is substantially perpendicular to the direction in which the magnetic object 100 and the magnet 103 face each other, as in the first embodiment. This GMR element has a pitch P = 0.6 (mm).
2 are arranged at the intervals of, to constitute the bridge circuit 14 of FIG.

As described above, the GMR element is composed of a laminated body (artificial lattice) in which magnetic layers (for example, Co) and magnetic layers (for example, Cu) each having a thickness of several to several tens angstroms are alternately laminated. This is an in-plane magneto-sensitive element whose resistance change rate due to a magnetic field is greater than that of an MR element. GM
The R element, unlike the MR element, generally does not have anisotropy in the direction of the magnetic field, and exhibits a resistance change regardless of the direction of the magnetic field if it is an in-plane magnetic field.

According to the third embodiment, similar to the first embodiment, an analog signal A similar to that shown in FIG. 4 can be obtained regardless of the rotation direction of the magnetic object 100. Further, since the magnetic detection sensitivity of the GMR element is higher than that of the MR element, the size of the bias magnet can be reduced, and the size of the magnetic detection device can be reduced.

Embodiment 4 In the case where a magnetoresistive element is used as the magnetic sensing element as described in Embodiment 1, the amount of change in resistance due to a change in the magnetic field is an average value of the element area. Therefore, in the fourth embodiment, the number of resistors is set to a bridge configuration of two elements, the size of the elements is reduced by half, and the element is arranged at a position where the amount of change in the magnetic field is large, so that the magnetic detection sensitivity can be improved.

If the size of the magnetic sensing element is reduced, the size of the integrated IC 104 itself can be reduced.

Embodiment 5 FIG. In the arrangement of the magnetic detection elements according to the first to fourth embodiments, the sensitivity of the magnetic detection is high, but there is a problem that the allowable amount of variation in assembling the magnetic detection elements and the magnet positions is small. Therefore, in the fifth embodiment, FIG.
As shown in the figure, when the magnetic detection elements 20a and 20b are arranged at a predetermined interval in the moving direction of the magnetic detection object 100,
There is an advantage that the assembling accuracy of the magnetism detecting elements 20a and 20b and the magnet 103 can be eased, and the mass productivity is excellent.

Embodiment 6 FIG. The sixth embodiment is an extension of the arrangement of the magnetic detection elements of the fifth embodiment, and uses a magnetic detection element patterned in a direction substantially perpendicular to the direction in which the magnetic object and the magnet face each other. , And to obtain an analog signal compatible with AC coupling.

FIG. 14 is a schematic perspective view showing a magnetic detector according to the sixth embodiment. In the sixth embodiment, the magnetic sensing surface of the magnetic sensing element is arranged so as to be substantially parallel to the facing direction of the magnetic object 100 and the magnet 103, and the segments 20a and 20d of the magnetic sensing element are arranged. The magnetic detection objects 100 are arranged at predetermined intervals in the moving direction.
Further, each of the segments 20a and 20d of the magnetic detection element is patterned in a direction substantially perpendicular to the direction in which the magnetic detection object and the magnet face each other.

Here, a GMR element is used as a magnetic detecting element, and each of the segments 20a and 20d has a width of 0.3.
(Mm) × length 0.66 (mm), in which a GMR film having a line width of 10 (μm) is meandering. The pitch between the centers of the segments 20a and 20d is 1.0 (mm).

The magnet is a rare earth magnet magnetized in a direction facing the magnetic object and the magnet, and has a size of 5 × 3 × 15 T (mm).

FIG. 15 shows the pattern direction and the analog signal waveform of the magnetic sensor according to the sixth embodiment. When the pattern direction of the magnetic detection element is parallel to the direction in which the magnetic detection object and the magnet are opposed to each other, the analog signal (the right signal waveform in FIG. 15) is not much different from the signal waveform of the conventional device. On the other hand, when the pattern direction of the magnetic detection element is perpendicular to the facing direction of the magnetic object and the magnet, the analog signal (the left signal waveform in FIG. 15) has almost no peak at the convex edge of the magnetic object. Thus, an AC-coupled analog signal that can be detected from a low rotation can be obtained.

As described above, according to the magnetic circuit configuration of the sixth embodiment, the allowable amount of variation in the mounting position of the magnet 103 is large, and an analog signal detectable from a low rotation can be obtained. In the magnetic circuit according to the sixth embodiment, the analog signal is not inverted even if the rotation direction of the magnetic detection object 100 is reversed.

Embodiment 7 In the sixth embodiment, the peak of the analog signal at the edge of the convex portion of the magnetic detection object 100 hardly occurs, but the influence on the signal accuracy is large. In particular, the mounting position of the magnetic detection element and the magnet position is shown in FIG.
4, the way of peaking of the analog signal changes, and the signal accuracy changes.

As a method of suppressing the peak which greatly affects the signal accuracy, as shown in FIG. 16, a magnetic guide 200 is provided at a position separated from the magnetic detection element with respect to the moving direction of the magnetic detection object 100. And good. Here, SPCC is used as the magnetic material guide 200.

By providing the magnetic material guide 200 according to the seventh embodiment, the displacement of the magnet 103 can be reduced by ± 0.
In the range of 3 (mm), the peak of the analog signal waveform does not occur. FIG. 17 shows an analog signal waveform depending on the presence or absence of the magnetic material guide 200.
The state shown by the broken line in the figure, which occurs when there is no 00, disappears when the magnetic material guide 200 is arranged. As a result, the signal accuracy due to the variation in assembling the magnetism detecting element and the magnet is improved.

Embodiment 8 FIG. The eighth embodiment relates to the improvement of the arrangement height of the magnetic material guide of the seventh embodiment. By configuring at least a part of the magnetic material guide 200 to be at least the same height as the magnetic sensing surface of the magnetic sensing element, Improve the temperature characteristics of analog signals.

In the magnetic circuit with a magnetic material guide shown in FIG. 16, the more the magnet is shifted in the + direction of the X axis, the greater the attenuation of the analog signal at high temperatures. FIG. 18 shows the magnetic material guide 2
The relationship between the height of 00 and the magnet position suitable for signal detection is shown. FIG. 18 shows that the analog signal decay rate decreases as the height L1 of the magnetic body guide 200 becomes the same as the magnetic sensing surface of the magnetic detection elements 20a and 20d (FIG. 18C). ). Further, when the height L1 of the magnetic material guide 200 is the same as the height of the magnetic detection element, it can be seen that the magnet center position 1 is in the range of 0 ± 0.2 (mm) as the optimum magnet position. The analog attenuation rate (%) in FIG. 18 is {V (25 ° C.) − V (130 ° C.)} / V (25 ° C.) × 1
00 is calculated.

Further, as shown in FIG. 19, the same effect as described above can be obtained even when the height of the magnetic body guide 200 is the same as that of the magnetic detection element mainly only on the side surface of the magnetic detection element.

Embodiment 9 FIG. The ninth embodiment relates to the improvement of the arrangement length of the magnetic material guide of the seventh embodiment. That is, as a method of further improving the temperature characteristic of the analog signal, it is preferable to configure the length of the magnetic body guide 200 to be longer than the length of the magnet. FIG. 18 shows the effect of improving the temperature characteristics by changing the length of the magnetic material guide. FIG. 18 shows that the analog signal attenuation rate decreases as the length L2 of the magnetic material guide 200 becomes longer than the length of the magnet 103 (FIG. 18C).

Embodiment 10 FIG. The magnetic circuit of the magnetic detection device shown in FIG. 19 is very effective for the AC coupling processing as described above when the width of the convex portion of the magnetic detection object is sufficiently larger than the magnetic detection element. However, when the shape of the magnetic detection object 100 is as shown in FIG. 20, that is, when the width of the projection 100a is as small as the width of the magnetic detection element,
If the interval of 00a is unequal and the minimum interval is equal to that of the magnetic detection element, the signal cannot be detected even if the amplification factor of the amplifier of the signal processing circuit is changed. FIG. 21 shows the relationship between the shape of the magnetic detection object and the analog signal in this case.

On the other hand, when the pattern direction of the magnetic sensing element is parallel to the facing direction of the magnetic object and the magnet as shown in the right side pattern of FIG. By occurring, FIG.
An analog signal whose waveform can be shaped as shown in FIG.

Embodiment 11 FIG. In the magnetic detection device according to the tenth embodiment, since the amount of change in the magnetic flux linking the magnetic detection element is small, it is necessary to increase the gain of the amplifier. For this reason, in the case of a rectangular magnet as in the above-described magnetic circuit, there is a case where the output after the amplifier is saturated due to a variation in the DC level of the analog signal due to a variation in assembling the magnetism detecting element and the magnet, and the signal cannot be detected.

To avoid this, the position of the magnet may be adjusted, the circuit constant of the amplifier may be individually adjusted, or the DC component may be cut before amplification. However, these methods have a problem that the product unit price is increased.

Therefore, in the eleventh embodiment, as shown in FIG. 23, the magnet 103 installed on the back side of the magnetic sensing element
Of the groove 103a on the surface facing the magnetic sensing elements 20a and 20d.
Is provided, the allowable amount of displacement between the magnetism detecting element and the magnet is greatly reduced. In this example, a GMR element having the same specifications as in the fifth embodiment is used as the magnetic detection element. The groove shape of the magnet 103 has a width of 4 (mm) and a depth of 1 (mm).

Embodiment 12 FIG. In a magnetic circuit (Embodiments 1 to 11) using the above-described magnetic detection element (especially a GMR element), as shown in FIG.
When the distance between the end face of the magnetic object and the center of the magnetic detection element (especially the GMR element) 20 is set in a range of ± 1.5 (mm), a magnetic circuit suitable as a magnetic detection device can be obtained.

[0090]

As described above, according to the first and second aspects of the present invention, the magneto-sensitive surface of the magnetic sensing element is arranged in a field where the magnetic field change in the direction facing the magnetic object is dominant. For example, an analog signal having a peak due to the edge of the convex portion of the magnetic detection object is not generated, and the gap is generated at the DC level.
An analog waveform having no characteristic cross point can be obtained. This analog signal does not invert the analog signal waveform corresponding to the unevenness of the magnetic object even if the rotation direction of the magnetic object is reversed. Therefore, if the waveform is shaped by the analog signal and a predetermined comparison voltage, immediately after the power is turned on. The unevenness of the magnetic detection object can be identified.

According to the third aspect of the present invention, the magnetic detecting element is formed in the integrated circuit device, and the magnetic field generating means magnetized in the direction facing the magnetic detection object is provided in parallel with the integrated circuit device. Therefore, there is an advantage that the terminals of the integrated circuit device can be configured to be flat. If the terminals are flat, the integrated circuit device including the chip component can be sealed with a highly reliable transfer mold as a general IC sealing technology. Is possible, and the reliability of the product can be improved.

According to the fourth aspect of the present invention, since the magnetic field generating means is positioned and installed by transfer molding, the positional accuracy of the magnetic detecting element and the magnet is improved, and the signal detecting accuracy is also improved.

According to the fifth aspect of the present invention, since the AC coupling method is employed as the waveform shaping processing method of the analog signal,
In the signal waveform after AC coupling, the Gap characteristic crosses substantially at the center of amplitude. As a result, the waveform can be accurately shaped with a general hysteresis amount (several tens mV) regardless of the shape of the magnetic detection object. In addition, even if the magnetic detection object rotates at a low speed, an accurate signal can be detected without generating an erroneous pulse.

According to the seventh aspect of the present invention, the magnetic detecting element is constituted by two linear segments, each segment is connected in series to form a bridge circuit, and each segment is opposed to the magnetic object. Since the pattern is perpendicular to the direction, the size of the magnetic sensing element can be reduced by half, and the magnetic sensing sensitivity can be improved by arranging the magnetic sensing element at a position where the amount of change in the magnetic field is large. Also, if the size of the magnetic detection element is reduced, the size of the magnetic detection device can be reduced.

According to the eighth aspect of the present invention, since the pair of magnetic detecting elements are arranged at a predetermined interval in the moving direction of the magnetic object, the magnetic detecting element and the magnetic field generating means (magnet) are assembled. The effect is that the accuracy can be relaxed and the mass productivity is excellent.

According to a ninth aspect of the present invention, the magnetic detecting element is disposed at a predetermined interval in the moving direction of the magnetic detection object, and the pattern direction of the magnetic detection element is set in the direction opposite to the magnetic detection object and the magnetic field generating means. Since it is formed in a direction substantially perpendicular to the direction, there is an effect that a magnetic detection device capable of detecting a signal from a low rotation with high signal accuracy can be obtained.

According to the tenth aspect, by providing the magnetic body guide at a position separated from the magnetic detection element in the moving direction of the magnetic detection object, there is an effect that the signal accuracy can be improved.

According to the eleventh aspect of the present invention, at least a portion of the magnetic body guide is formed at the same height or higher than the magnetic detecting element, so that the temperature characteristics of the amplitude of the analog signal are reduced and the signal accuracy is improved. is there.

The twelfth aspect of the invention has the effect that the temperature characteristic of the amplitude of the analog signal is reduced and the signal accuracy is improved by setting the length of the magnetic material guide to be longer than the length of the magnetic field generating means.

According to the thirteenth aspect of the present invention, the magnetic detecting elements are arranged at predetermined intervals in the moving direction of the magnetic object,
And, by forming the pattern direction of the magnetic sensing element in a direction substantially parallel to the facing direction of the magnetic object and the magnetic field generating means, when the convex shape of the magnetic object is small and the interval between the convex portions is small, There is an effect that the signal can be detected with high accuracy.

According to the fourteenth aspect, the surface of the magnetic field generating means (magnet) of the thirteenth aspect, which faces the magnetic detection element,
Provision of the groove in the direction parallel to the direction in which the magnetic detection object and the magnet oppose each other has the effect of reducing variations in the mounting position of the magnetic detection element and the magnetic field generating means (magnet).

According to the fifteenth aspect of the present invention, the center position of the magnetic detecting element is set at a predetermined position, for example, ± 1.5 (mm) from the end of the surface of the magnetic field generating means (magnet) facing the magnetic object.
In this case, there is an effect that a magnetic circuit suitable as a magnetic detection device can be obtained.

According to the sixteenth aspect, by using a giant magnetoresistive element having high magnetic detection sensitivity as the magnetic detection element, it is possible to reduce the size of a magnetic circuit such as a magnet which is a magnetic field generating means. There is an effect that the size of the magnetic detection device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a magnetic detection device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a bridge circuit of the magnetic detection element according to the first embodiment.

FIG. 3 is a block diagram of a signal processing circuit of the magnetic detection device of the present invention.

FIG. 4 is a diagram showing an analog signal waveform of the magnetic detection device according to the first embodiment.

FIG. 5 is a diagram for explaining the reason why no peak occurs in the analog signal A according to the first embodiment;

FIG. 6 is a diagram for explaining the reason why no peak occurs in the analog signal A according to the first embodiment;

FIG. 7 is a diagram for explaining the reason why no peak occurs in the analog signal A according to the first embodiment;

FIG. 8 is a cross-sectional view illustrating the structure of the magnetic detection device according to the first embodiment.

FIG. 9 is a schematic perspective view showing a magnetic detection device according to another example of the first embodiment.

FIG. 10 is a diagram showing an analog signal waveform after AC coupling according to the second embodiment.

FIG. 11 is a diagram showing a relationship between a rotation speed of a magnetic detection object and a signal processing waveform according to the second embodiment.

FIG. 12 is a schematic perspective view showing a magnetic detection device according to a third embodiment.

FIG. 13 is a schematic perspective view showing a magnetic detection device according to a fifth embodiment.

FIG. 14 is a schematic perspective view showing a magnetic detection device according to a sixth embodiment.

FIG. 15 shows a pattern direction and an analog signal waveform of a magnetic detection element according to a sixth embodiment.

FIG. 16 is a schematic perspective view showing a magnetic detection device according to a seventh embodiment.

FIG. 17 is a diagram illustrating an analog signal waveform according to the presence or absence of a magnetic body guide according to the seventh embodiment.

FIG. 18 shows the relationship between the height of a magnetic body guide and the position of a magnet suitable for signal detection.

FIG. 19 is a schematic perspective view showing a magnetic detection device provided with a magnetic body guide according to an eighth embodiment.

FIG. 20 is a diagram showing a shape of a magnetic detection object described in a tenth embodiment.

FIG. 21 is a diagram showing an analog signal of the magnetic circuit according to the eighth embodiment corresponding to the magnetic detection object in FIG. 20;

FIG. 22 is a diagram illustrating an analog signal of the magnetic circuit according to the ninth embodiment corresponding to the magnetic detection object in FIG. 20;

23A and 23B are a plan view and a front view showing a magnetic detection device according to an eleventh embodiment.

FIG. 24 is a side view showing a magnetic detection device according to a twelfth embodiment.

FIG. 25 is a side view showing a relative positional relationship between a conventional rotation detection device and a magnetic detection object.

FIG. 26 is a cross-sectional view showing a structure of a conventional rotation detecting device.

FIG. 27 is a perspective view showing a relative positional relationship between a conventional magnetic magnetic detection object and a magnetic detection head of a rotation detection device.

FIG. 28 is a circuit diagram showing a connection state of a bridge circuit by a magnetic detection element.

FIG. 29 is a characteristic diagram showing a change in resistance value of a general GMR element with respect to a magnetic field.

30 is a diagram showing a magnetic detection object, each midpoint voltage of the bridge circuit of FIG. 28, and an analog signal which is a differential output thereof.

FIG. 31 is a block diagram of a signal processing circuit of a rotation detection device as a general magnetic detection device.

FIG. 32 is a diagram illustrating a change in the position of a magnetism detecting element and a magnet and an analog signal.

FIG. 33 is a diagram showing a relationship between a rotation direction of a conventional magnetic detection object and an analog signal.

FIG. 34 is a diagram showing a relationship between a rotation speed of a conventional magnetic detection object and a signal processing waveform.

[Explanation of symbols]

1 rotation detection device (magnetic detection device), 10 resin, 14
Bridge circuit, 14a, b Midpoint voltage of bridge circuit, 20, 20a-d Magnetic sensing element (GMR element, M
R element), 30 buffers, 40 differential amplifier, 50
Comparator, 100 magnetic object, 100a convex part of magnetic object, 100b concave part of magnetic object, 10
3 Magnet, 104 IC, 200 Magnetic body guide.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Izumi Shinjo 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2F063 AA23 AA35 BA07 BB05 BC03 BD16 CA09 CA34 DA01 DA04 DB07 DC08 DD02 GA52 GA69 LA11 LA23 LA27 2F077 AA25 NN04 NN21 PP14 TT16 TT35 2G017 AA01 AB05 AC04 AC06 AC07 AC09 AD55 AD63 AD65 BA09

Claims (16)

[Claims] A magnetic field generating means disposed opposite to a magnetic detection object, a magnetic detection element to which a magnetic field is applied by the magnetic field generation means, and an output from the magnetic detection element in response to movement of the magnetic detection object. A magnetic detection device provided with a signal processing circuit for shaping the waveform of an analog signal to be obtained, wherein a change in a magnetic field generated by the magnetic field generating means is dominant in response to a change in a distance from the magnetic object A magnetic detection device, wherein a magnetically sensitive surface of the magnetic detection element is arranged in a field. 2. A magnetic field generating means arranged to face a magnetic object, a magnetic detecting element to which a magnetic field is applied by the magnetic field generating means, and a magnetic field output from the magnetic detecting element in response to the movement of the magnetic object. A magnetic detection device provided with a signal processing circuit for shaping the waveform of an analog signal, wherein a magnetically sensitive surface of the magnetic detection element is disposed substantially parallel to a direction facing a magnetic detection object. Magnetic detection device. 3. The integrated circuit device according to claim 2, wherein said magnetic detecting element is formed in an integrated circuit device, and magnetic field generating means magnetized in a direction facing said magnetic detection object is provided in parallel with said integrated circuit device. The magnetic detection device according to claim 1. 4. The magnetic detecting device according to claim 3, wherein the magnetic field generating means is positioned and installed by transfer molding. 5. The magnetic detection device according to claim 1, wherein a waveform shaping processing method of an analog signal is an AC coupling method. 6. The magnetic sensing element is constituted by four linear segments, each segment constituting two pairs of series circuits, and each series circuit being connected in parallel to constitute a bridge circuit. 4. A pattern perpendicular to the direction in which the magnetic object is opposed to each other, and each series circuit is arranged at a predetermined interval substantially parallel to the facing direction. Item 7. The magnetic detection device according to Item. 7. The magnetic detecting element is constituted by two linear segments, each segment is connected by a serial circuit to form a bridge circuit, and each segment is arranged in a direction facing the magnetic object. The magnetic detection device according to claim 1, wherein the magnetic detection device has a vertical pattern. 8. The apparatus according to claim 1, wherein a pair of magnetic detecting elements are arranged at a predetermined interval in a moving direction of the magnetic detection object. Magnetic detector. 9. The magnetic detection device according to claim 8, wherein a pattern direction of the magnetic detection element is formed in a direction substantially perpendicular to a direction in which the magnetic detection object and the magnetic field generating means face each other. 10. The magnetic body guide according to claim 1, wherein a magnetic body guide is provided at a position separated from the magnetic detecting element with respect to the moving direction of the magnetic object. Magnetic detection device. 11. The magnetic detection device according to claim 10, wherein at least a part of the magnetic body guide is configured to be at least as high as the magnetic detection element. 12. The magnetic detecting device according to claim 10, wherein the length of the magnetic material guide is longer than the length of the magnetic field generating means. 13. A pattern direction of the magnetic sensing element,
9. The magnetic detection device according to claim 8, wherein the magnetic detection device is formed in a direction substantially parallel to a direction in which the magnetic detection object and the magnetic field generating means face each other. 14. The magnetic field according to claim 13, wherein a groove in a direction parallel to a direction in which the magnetic object and the magnetic field generating means face each other is provided on a surface of the magnetic field generating means facing the magnetic detecting element. Detection device. 15. The magnetic field detecting device according to claim 1, wherein a center of the magnetic detecting element is arranged at a predetermined position from an end of a surface of the magnetic field generating means facing the magnetic object.
The magnetic detection device according to any one of the above. 16. The magnetic detecting device according to claim 1, wherein a giant magnetoresistive element is used as the magnetic detecting element.