JP2666613B2 - Magnetic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a magnetic sensor using a magnetoresistive element.

[0002]

2. Description of the Related Art Conventionally, a magnetic sensor using a magnetoresistive element has been known. The magnetic sensor is used, for example, in a magnetic line sensor.
No. 75087.

FIG. 6 shows a configuration of a magnetic sensor according to a conventional example. Magnetic sensor 10 shown in FIG.
Is provided with a magnetoresistive element in which a pair of magnetically sensitive parts 14a and 14b are formed on the element substrate 12. The magnetic sensing part 14a,
14b is formed of a material such as InSb, for example, and is formed on the element substrate 12 by etching or vapor deposition.

[0004] The magnetoresistive element comprises magnetic sensing parts 14a, 14a.
A signal is output according to a change in the magnetic field applied to b. That is, when a magnetic substance (for example, a magnetic pattern printed on a banknote with magnetic ink) passes along the magnetic sensing portions 14a and 14b of the magnetoresistive element, the magnetoresistive element outputs a signal with the passage.

[0005] Further, this conventional example includes a magnet 16 for magnetically biasing the magnetoresistive element. Usually, since the output signal voltage of the magnetoresistive element for detecting the magnetic pattern of the bill is weak, it is difficult to handle the bill as it is. Therefore, in this conventional example, a magnetic bias is applied to the magnetoresistive element by the magnet 16 to move the magnetic operating point, so that the output signal level can be increased with respect to a minute change in the magnetic field.

Further, the magnetoresistive element and the magnet 16 are housed in a case 18. Although not shown in detail in this figure, the case 18 has a chamber for accommodating the magnet 16 and the magnetoresistive element. The upper part of the case 18 is covered with a metal cover 20. In such a configuration, the metal cover 20 functions as a detection surface.

In this conventional example, the conductor wire 2
2 are provided. The conductor wire 22 is a conductor wire that generates a reference AC magnetic field, and its surface is insulated.

[0008] reference alternating magnetic field and is, and FIG. 6 (b) and (c)
Is a magnetic field generated when an alternating current having a frequency fa (Hz) is applied to the conductor wire 22. Fig. 6 (b)
Is represented by the magnetic flux density B.

[0009] In the conventional example, the conductor wires 2 shown in FIG. 5
As shown in FIG. 6A, when no current is flowing through the magnetic field 2, the magnetic field generated from the permanent magnet 16 is applied perpendicularly to the magnetic sensing portions 14a and 14b of the magnetoresistive element near the magnetic pole surface of the permanent magnet. For this reason, the strengths of the magnetic fields applied to the magnetic sensing portions 14a and 14b of the two magnetoresistive elements are substantially equal.

[0010] The two magnetoresistive elements are connected as shown in FIG. 6 (c), the resistance of the two magnetoresistive elements is substantially equal to the output V _out V when the applied voltage is V _in
The voltage becomes _in / 2.

Next, FIG.5In (b), the conductor wire 22 is
When a current I flows from the front surface to the back surface,
A magnetic field B is generated around the conductor wire 22. This magnetic field B
Fig. Shows the magnetic field generated from the permanent magnet5Random as in (b)
And the magnetic flux density applied to the magnetic sensing portion 14a of one element is high.
And the magnetic field applied to the magnetic sensing part 14b of the other element
The bundle density is low. Therefore, the resistance of the two magnetoresistive elements
Anti-change rate is different,6Output V of (c)_outIs V_in/ 2
Fluctuates from Similarly, when the direction of the current changes, the output V_out
The change of the sign is reversed. As a result, the current I is changed to the frequency f
_a(Hz) output V_outIs a figure6
Frequency f as shown in (c)_aSimulated voltage of (Hz)
Output.

The reason why the conductor wire 22 for generating such a reference AC magnetic field is used is to perform a so-called initial check (initial diagnosis). The characteristics of the magnetoresistive element may change due to so-called aging, or the magnetoresistive element may fail. In such a case, even if the reference AC magnetic field is applied to the magnetic sensing units 14a and 14b, a simulation signal of a predetermined level cannot be obtained. Therefore, it is possible to diagnose whether or not a characteristic deterioration, a failure, or the like has occurred, based on whether or not a simulation signal of a predetermined level is obtained from the magnetoresistive element while the reference AC magnetic field is being generated. Therefore, by using the conductor wire 22 and using it for the initial diagnosis, it is possible to evaluate the characteristic deterioration and the like by simple means.

[0013]

However, in such a configuration, the positional relationship between the conductor wire and the magnetic sensing portion is not constant. That is, the conductor wire is fixed to the metal cover or the like, and the positional accuracy is not necessarily ensured for the magnetic sensing portion. In addition, it is difficult to fix the conductor wire with high accuracy, and if the case is vibrated or deformed after the conductor wire is attached, the output signal (simulated signal) is affected by the vibration or deformation. It will be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the positional relationship between the magnetically sensitive part and the conductor wire is hard to change, so that the initial diagnosis can be performed more easily. It is an object to provide a simple magnetic sensor.

[0015]

In order to achieve such an object, the present invention provides a method in which a perpendicular magnetic field is applied by a magnet.
Deposited and formed on the pair and approximately parallel and the same substrate surface of the magnetic sensitive sections
A diagnostic current or a current to be detected is passed through the conductor .

[0016]

According to the present invention, the diagnosis is performed on the same substrate surface as the magnetic sensing portion.
Conductor for or the current to be detected for cross current are arranged, Katsuko
These are Ru is magnetically biased by the magnet. Therefore, the positional relationship between the conductor and the magnetic sensing portion is not easily changed, and as a result, the reproducibility of the output signal level is improved, and the case and the like are resistant to deformation and vibration.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same components as those in the conventional example shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows the configuration of a magnetic sensor according to a first embodiment of the present invention. FIG. 1A is a plan view of the element substrate 12 seen from above, FIG. 1B is a side view, and FIG. 1 (d) shows the connection.

In this embodiment, a pair of magneto-sensitive sections 14 are provided.
In addition to a and 14b, a conductor pattern 22 is formed on the element substrate 12 by adhesion. The deposition is performed, for example, by etching. The element substrate 12 is, for example, ferrite, the magnetic sensing portions 14a, 14b are made of InSb or the like, and the conductor pattern 22 is made of InSb, Al, Cu, or the like.

When a reference AC current is applied to the conductor pattern 22 formed on the element substrate 12 in parallel with the magnetic sensing portions 14a and 14b, a reference AC magnetic field is generated and the reference AC magnetic field is generated. 14b. Then, a simulation signal output is obtained from the magnetic sensing units 14a and 14b according to the same principle as that of the conventional example shown in FIG. 6 , and self-diagnosis can be performed based on the level of the simulation signal.

FIG. 2 shows a side view of a magnetic sensor according to a second embodiment of the present invention, in particular, an element substrate 12 thereof. In the magnetoresistive element shown in this figure, a conductor pattern 22 is formed on both sides of a pair of magnetosensitive portions 14a and 14b. Even in this case, similarly to the first embodiment, the reference alternating magnetic field can be applied to the magnetic sensing units 14a and 14b.

[0022] In these examples, the conductor pattern 22 and the magnetic sensitive section 14a, the distance between 14b, are close compared to the conventional example shown in FIG. As a result, the simulation signal level can be increased, and the initial diagnosis can be performed more accurately. Conversely, the reference AC current does not need to be as large as in the past.

Conventionally, a manufacturing process for fixing the conductor wire 22 was required. In contrast, the first and
In the second embodiment, the formation of the conductor pattern 22 is realized without performing such a step. Further, since the conductor pattern 22 is disposed on the element substrate 12, even when the case 18 or the like is constantly deformed or vibrated, the output signal is not affected. As described above, it is possible to more accurately and safely evaluate the characteristic change and the failure.

The configuration of the present invention is not limited to the magnetic sensor described above. The magnetic sensors according to the first and second embodiments can be used, for example, as a sensor for reading a magnetic pattern printed on a banknote with magnetic ink. Can also be applied to a sensor that attempts to detect.

FIG. 3 shows an example of the configuration of a magnetic sensor having such a current detection function.

[0026] Figure 3 as (a), the magnetic sensor according to a third embodiment, a pair of magnetic sensitive sections 3 on the element substrate 30
This is a configuration in which 2a, 32b and a conductor layer 34 are formed. A pair of electrodes 36 and 38 are extended from the magnetic sensing portions 32a and 32b, respectively, and a pair of electrodes 40 and 42 are extended from the conductor layer 34, respectively. Conductive layer 34
Is not directly formed on the element substrate 30 but is formed via ohmic contact with the semiconductor layer 44.

The conductor layer 34 is a conductor through which a current to be detected flows in this embodiment. That is, as shown in FIG. 4, when the detected current I flows through the conductor layer 34, the output voltage V is obtained from the middle point of the connection between the magneto-sensitive portions 32a and 32b. Sensitive sections 32a, 32b, as shown in FIG. 4
As shown in (1), the electrodes connected in series are selected so as to be in a differential state. A power supply 46 is connected to the pair of magnetic sensing units 32a and 32b connected in series.
When a voltage is applied to the magnetic field, the resistance values of the magnetic sensing portions 32a and 32b change due to the magnetic field generated by the detected current I, and as a result, the value of the output voltage V changes. The change in the value of the output voltage V indicates the amount and direction of the current. Although not shown, the magnetic sensor of FIG. 3 is also attached to the magnetic pole surface of the permanent magnet.

The operation of this embodiment will be described. Conductive layer 34
When no current is flowing through the magnetic sensing units 32a and 32
Only the magnetic field related to the bias by the magnet 18 not shown is applied to b. Therefore, in this state, the magnetic sensing portions 32a,
The magnetic field applied to 32b is balanced, and the output voltage V is also stable.

Thereafter, when a current flows through the conductor layer 34, a magnetic field is generated. This magnetic field is combined with the magnetic field generated by the magnet 18 (not shown), and as a result, imbalance occurs in the magnetic fields applied to the magnetic sensing units 32a and 32b. This imbalance changes the resistance value of the magnetoresistive element, and thus changes the value of the output voltage V appearing at the connection midpoint. Since the intensity and direction of the magnetic field generated by the conductor layer 34 change depending on the amount and direction of the current I, the current I can be detected by observing the amount and direction of the change in the output voltage V.

As described above, the present invention can be applied to a current sensor, and as a result, a small, lightweight, and inexpensive sensor is realized. A conventional current sensor uses, for example, a Hall element. In order to operate the Hall element, a coil, a core, a yoke, and the like for applying a magnetic field are required. In this embodiment, such a large or heavy member is not required, and the above-described effects can be obtained. Of course, it goes without saying that the effect of improving the arrangement accuracy obtained in the first to third embodiments can also be obtained.

[0031]

As described above, according to the present invention,
A conductor is formed on the same substrate surface as the magnetically sensitive part so as to be substantially parallel to the pair of magnetically sensitive parts.
Since the detection current is caused to flow , the positional accuracy of the conductor with respect to the magnetic sensing part is improved, and the reproducibility of the signal is improved. In addition, the size is reduced, and the manufacture becomes easy.

When used as a magnetic sensor for detecting bills and the like, there is an advantage that no other magnetic field means for self-diagnosis is required. There is an advantage that only the current to be detected needs to flow.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a magnetic sensor according to a first embodiment of the present invention. FIG. 1A is a plan view of an element substrate, and FIG.
1 (b) is a side view, FIG. 1 (c) is a cross-sectional view in a state where it is housed in a case and covered with a cover, and FIG. 1 (d) is a connection diagram.

FIG. 2 is a diagram showing a configuration of a magnetic sensor according to a second embodiment of the present invention.

FIG. 3 shows a configuration of a magnetic sensor according to a third embodiment of the present invention .
FIG. 3A is a top view of the element substrate, and FIG.
(B) is an AA 'sectional view.

FIG. 4 is a diagram showing a circuit configuration of a third embodiment.

FIG. 5 is a view showing the action of a reference AC magnetic field, and FIG.
5A shows a state in which no current flows, and FIG.
FIG.

FIG. 6 is a diagram showing a configuration of a magnetic sensor according to a conventional example.
6 (a) shows the cross section, and FIG. 6 (b) shows the action of the conductor wire.
FIG. 6C is a diagram showing a simulation signal output, respectively.
You.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic sensor 12 Element board 14 Magnetic sensing part 16 Magnet 22 Conductive pattern 30 Element board 32 Magnetic sensing part 34 Conductive layer 36,38,40,42 Electrode

Claims (1)

(57) [Claims] 1. A joining a pair of magnetoresistive element pairs sensitive portion are arranged in parallel on a substrate by a change in the magnetic field resistance value changes to output a signal of a level corresponding to this, the magnetic Ki抵
A magnet which applies a magnetic field perpendicularly to the magneto-sensitive part of the resistance element.
In the magnetic sensor, the magnetic sensor is attached substantially parallel to the pair of magnetic sensing portions and on the same substrate surface.
A magnetic sensor comprising a conductor formed and through which a diagnostic current or a detected current flows .