JPH06100477B2 - Magnetoresistive element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic sensor for measuring a stationary position or a moving state of an object such as a motor in which a peripheral magnetic field repeats the same change every predetermined length. The present invention relates to a magnetoresistive element.

(Prior Art) There is a magnetoresistive element that utilizes the magnetoresistive effect of a ferromagnetic material. 20 and 21 schematically show such a conventional magnetoresistive element. 20 and 21, a magnetoresistive element 1 formed by a ferromagnetic film on a non-magnetic substrate in a "U" -shaped pattern is used for recording a magnetic signal on a recording medium 2 magnetized at a period λ. It is arranged so as to face the surface and detects the magnetic field around the recording medium 2. The magnetoresistive element 1 has two detectors A and B arranged in parallel with each other, one end of each of the two detectors A and B is connected and connected in series, and the opposite ends are It serves as an output terminal for the detection signal. Such a magnetoresistive element 1 has the advantages that it is turned into a U-shape and has a high impedance to reduce power consumption, and that the output terminals are gathered on one side, so that wiring is easy.

In the example of FIG. 20, the detection bodies A and B are the magnetization period λ of the recording medium 2.
21. In the example of FIG. 21, the detectors A and B are arranged at a smaller interval a than the magnetizing period λ of the recording medium 2.
They are arranged at an interval of / 2.

(Problems to be Solved by the Invention) According to the conventional example of FIG. 20, as shown in FIG. 22, the resistance change of the detection body A is caused by the deviations of the detection bodies A and B by the distance a. The resistance change R _B between R _A and the detection body B causes a phase difference of 4πa / λ with each other. Now, the resistance changes R _A and R _B of the detection bodies A and B are set as in the following equation.

Here, Ro is the direct current component of the resistance change, RΔ is the amplitude of the alternating current component of the resistance change, and x is the magnetoresistive element 1 in the longitudinal direction of the recording medium.
Is the relative movement distance of.

The resistance R of the entire magnetoresistive element 1 is the resistance R of the detection bodies A and B.
_Since it is the sum of _A and R _B , Becomes The coefficient cos (2πa / λ) in the second term of the above equation indicates that the amplitude of the resistance change changes depending on the distance a between the detection bodies A and B. This term is monotonically decreasing in the range of 0 ≦ a ≦ λ / 4. That is, within the above range, the smaller a is, the larger the resistance change can be obtained even with the same Ro and RΔ.

FIG. 23 shows the relationship between the upper surfaces, where A is the change in the magnetic resistance of the detection element A, and B is the change in the magnetic resistance of the detection element B that is provided at a position displaced from the detection element A. The sum of the magnetic resistance changes of the detection elements A and B is indicated by R1. Now, assuming that the two detection elements C are vertically overlapped with each other in the center between the detection elements A and B,
Moreover, if they are connected in series, the phase difference of the magnetoresistive change of the two magnetoresistive elements C is zero, so the sum of the magnetoresistive changes of these two magnetoresistive elements C is shown in FIG. It can be seen that the amplitude increases.

However, in the conventional example shown in FIG. 20, since the detection elements A and B are on the same plane, it is impossible to make the distance a between the detection elements A and B zero, and in particular, when the signal recording wavelength λ becomes small, the coefficient cos (2πa / λ) becomes small, and the amplitude of resistance change becomes small. Therefore, in the conventional example of FIG. 20, the recording wavelength λ
However, there is a problem in that a large rate of resistance change cannot be obtained when the motor speed is to be detected with high accuracy by reducing the value.

Further, in the conventional example of FIG. 21, the distance between the detection bodies A and B is λ / 2.
That is, the two detectors A and B are electrically equivalent to each other. Therefore, the coefficient cos (2πa / λ) becomes -1, and the maximum resistance change is obtained. However, the space between the detectors A and B inevitably becomes large, which is inconvenient for downsizing the magnetoresistive element.

An object of the present invention is to connect a plurality of magnetic films in series in order to obtain a magnetoresistive element having a small size and a high impedance, thereby making it possible to make the phase difference of the resistance change of each magnetic film zero. To provide a large magnetoresistive element.

(Means for Solving the Problems) In the magnetoresistive element of the present invention, a plurality of magnetic films constituting the magnetoresistive element and the insulating film are formed on one surface of the substrate in a direction perpendicular to the surface facing the recording medium. By alternately stacking the magnetic films, a part of the magnetic films are stacked without interposing the insulating film and connected in series to be arranged on the substrate, so that all the magnetic films are simultaneously formed. It is characterized in that the magnetic signals at the same position on the recording medium are detected, and the phase difference of the magnetoresistance change of the plurality of magnetic films arranged in layers is set to zero.

(Operation) Since the magnetic film forming the magnetoresistive element is vertically stacked on the surface facing the recording medium via the insulating film and connected in series, each magnetic film with respect to the moving direction of the recording medium of the magnetic signal. There is no deviation, and the phase difference of the resistance change of each magnetic film becomes zero, and the change of the magnetic resistance becomes large.

(Embodiment) FIGS. 1 to 6 show an embodiment of the present invention. 1 to 6, a ferromagnetic thin film 4 having a magnetoresistive effect is formed on the surface of a non-magnetic substrate 3 made of glass or the like.
Are formed. Most of this magnetic thin film 4 is formed substantially linearly along the center line of the substrate 3 in the longitudinal direction, and a part 4a to be a terminal is formed to be bent to one side. . As shown in FIG. 2, an insulating film 5 is formed thereon, except for the terminal portion 4a of the magnetic thin film 4 and the end portion 4b on the opposite side thereof. Insulation film 5
A ferromagnetic thin film 6 having a magnetoresistive effect is further formed thereon. As shown in FIG. 3, most of the magnetic thin film 6 is formed in a linear shape substantially along the center line of the substrate 3 in the longitudinal direction, and the linear portion is formed in the insulating film 5. It overlaps with the linear portion of the magnetic thin film 4 via the. The magnetic thin film 6 has the end portion on the same side as the terminal portion 4a of the magnetic thin film 4 as a portion 6a to be a terminal.
Is formed in a shape that is bent in the direction opposite to the bending of the terminal portion 4a, and the other end portion 6b of the magnetic thin film 6 protrudes from the end portion of the insulating film 5 and directly overlaps with the end portion 4b of the magnetic thin film 4. There is. Therefore, the magnetic thin film 4 and the magnetic thin film 6 are formed so as to have the same magnetoresistive characteristics, and are connected in series and formed to be folded along the line IV-IV. A protective film 7 is further formed on the magnetic thin film 6 so as to cover the magnetic thin film 6 and the other portions of the magnetic thin film 4 excluding the respective terminal portions 6a, 4a.

In this way, the two magnetic thin films 4 and 6 are stacked in the direction perpendicular to the surface of the substrate 3 and connected in series to form the magnetoresistive element 8.

This magnetoresistive element 8 is, as shown in FIG.
The recording medium 9 is arranged so as to face the magnetic signal recording surface of the recording medium 9 which is periodically magnetized in the moving direction and repeatedly recorded with magnetic signals. The magnetoresistive element 8 is arranged such that its linear portion is orthogonal to the moving surface of the recording medium 9. Since the magnetic thin films 4 and 6 forming the magnetoresistive element 8 overlap each other in the vertical direction with respect to the surface facing the recording medium 9, the plurality of magnetic thin films 4 and 6 are at the same position on the recording medium 9 at the same time. When a magnetic signal is detected, the mutual distance between the two magnetic thin films 4 and 6 with respect to the moving direction of the recording medium 9 becomes zero, and the phase difference in resistance change between the two magnetic thin films 4 and 6 becomes zero. That is, a in the formula (3) is zero, and the amplitude of the resistance change of the magnetoresistive element 8 is 2RΔ, as indicated by R2 in FIG. In FIG. 8, R1 shows the resistance change when a is not zero, that is, when the magnetic thin films as the detectors are displaced from each other as in the conventional example of FIG. As is clear from FIG. 8, according to the above-mentioned embodiment, there is an effect that the amplitude of resistance change becomes large.

Next, the embodiment shown in FIGS. 9 to 12 will be described. In FIGS. 9 to 12, a ferromagnetic thin film 11 having a magnetoresistive effect is formed on the surface of a substrate 10 such as glass.
The magnetic thin film 11 is linearly formed along the center line of the substrate 10 in the longitudinal direction, and one end of the magnetic thin film 11 is formed to be a terminal portion 11a. An insulating film 12 is formed thereon except for the terminal portion 11a and the opposite end portion 11b.
A ferromagnetic thin film 13 having a magnetoresistive effect is further formed on the insulating film 12. As shown in FIG. 10, the magnetic thin film 13 is linearly formed along the longitudinal center line of the substrate 10 and overlaps with the magnetic thin film 11 via the insulating film 12. The magnetic thin film 13 is a terminal portion of the magnetic thin film 11.
The end portion on the same side as 11a is formed wide to form a terminal portion 13a, and the terminal portion 13a sandwiches the insulating film 12 and the magnetic thin film 1a.
It overlaps with a part of the terminal portion 11a of 1. On the other hand, the other end 13b of the magnetic thin film 13 protrudes from the end of the insulating film 12 and directly overlaps with the terminal 11a of the magnetic thin film 11. Therefore,
The magnetic thin film 11 and the magnetic thin film 13 are vertically stacked on the surface of the substrate 10 and are connected in series. A protective film 14 is further formed on the magnetic thin film 13. Protective film
Reference numeral 14 is formed so as to cover other portions of the magnetic thin films 11 and 13 excluding the terminal portions 11a and 13a.

This embodiment is basically the same as the embodiment of FIGS. 1 to 6 except that the terminal portion 11a of the lower magnetic thin film 11 is made longer than the terminal portion 13a of the upper magnetic thin film 13. Thus, the shapes of the magnetic thin films 11 and 13 and the insulating film 12 are simplified. The magnetic detecting portions of the magnetic thin film 11 and the magnetic thin film 13 have the same magnetoresistive characteristics.

Next, the embodiment shown in FIGS. 13 to 17 will be described. In this embodiment, the magnetic thin films are stacked in three layers in order to make the magnetoresistive element have a high impedance. 13 to 17, the magnetic thin film 16 is first formed on the surface of the substrate 15.
Is linearly formed along the center line of the substrate 15 in the longitudinal direction, and one end thereof is formed wide to form the terminal portion 16a. As shown in FIG. 14, an insulating film 17 is formed on the magnetic thin film 16 except for a part of the terminal portion 16a and the end portion 16b on the opposite side. A magnetic thin film 18 is formed on the insulating film 17 along the longitudinal center line of the substrate 15 and
It is linearly formed so as to overlap with the magnetic thin film 16 with the 17 interposed therebetween. The magnetic thin film 18 is the terminal portion 16a of the magnetic thin film 16.
The side end 18b is isolated from the magnetic thin film 16 by the insulating film 17, but the opposite end 18a protrudes from the end of the insulating film 17 and directly overlaps the end 16b of the magnetic thin film 16. An insulating film 19 is formed on the magnetic thin film 18 as shown in FIG. The insulating film 19 is formed so as to cover all the other parts of the magnetic thin film 18 except the one end 18b of the magnetic thin film 18. A magnetic thin film is further formed on the insulating film 19.
Reference numeral 20 is linearly formed along the longitudinal center line of the substrate 15 and overlapped with the magnetic thin film 18 with the insulating film 19 interposed therebetween.
The magnetic thin film 20 has a terminal portion 20a formed by widening the end portion on the opposite side of the magnetic thin film 16 to the terminal portion 16a forming side, and also the end portion 20b on the opposite side to the terminal portion 20a forming side. Is protruded from the end of the insulating film 19 and directly overlapped with the end 18b of the magnetic thin film 18. In this way three magnetic thin films 16,
18 and 20 are separated from each other by insulating films 17 and 19, respectively, and are stacked in three layers in a direction perpendicular to the surface of the substrate 15, and a magnetic thin film.
Ends 16b and 18a of 16 and 18 and ends 18 of magnetic thin films 18 and 20
b and 20b are directly overlapped with each other to form magnetic thin films 16, 18, 20
Are connected in series. From the top of the magnetic thin film 20,
As shown in FIG. 17 and FIG. 17, the terminal portion of the magnetic thin film 16
16a and the terminal portion 20a of the magnetic thin film 20 are all protective films except for
Although it is covered with 21, the protective film 21 is not shown in FIG. 13 in order to avoid complication of the drawing. Each magnetic thin film 16, 18, 20
Has the same magnetic characteristics.

The magnetoresistive element according to the above embodiment is also arranged so as to face the moving surface of the medium on which the magnetic signal is repeatedly recorded. The magnetic thin films 16, 18 and 20 are stacked vertically in the direction perpendicular to the surface facing the recording medium.
Since each of the magnetic thin films 16, 18 and 20 simultaneously detects the magnetic signal at the same position on the recording medium, the magnetic thin films 16, 18 and 20 have zero displacement with respect to the moving direction of the recording medium and the resistance change of each magnetic thin film 16, 18, 20. Has an advantage that the amplitude of the resistance change becomes large. Moreover, three magnetic thin films 16, 18, 20
Since they are connected in series, the impedance is also high.

Next, the embodiment shown in FIGS. 18 and 19 will be described. In this embodiment, a resistance change having a phase difference of 90 ° is detected by using a detection body composed of two magnetic thin films that are provided in an overlapping manner. In FIG. 18 and FIG. 19, four magnetic thin films 23, 24, 2 constituting a magnetoresistive element are formed on the substrate 22.
5, 26 are formed in parallel with each other and at a distance of λ / 8 from each other. Terminal portion 23a from the magnetic thin film 23
However, from the magnetic thin films 24 and 26, the common terminal portion 24a is
The terminal parts 25a are pulled out from 5, and these terminal parts are
It is formed in a shape arranged on one side edge of 22. Above the respective magnetic thin films 23, 24, 25, 26, the terminal portions 23a, 24a, 25
The insulating film 32 is formed except for a. As shown in FIG. 19, the insulating film 32 includes magnetic thin films 23, 2
The window holes 32a, 32b, 32c, 32d having a width larger than the width of each of the magnetic thin films described above are open at the portions facing the tips of 4, 25, 26.
And the window portions 32e and 32f are formed by opening the terminal portions 23a and 25a and the portions near them. Insulation film 32
From above, four magnetic thin films 27, which are vertically stacked on each of the magnetic thin films 23, 24, 25, and 26 to form a magnetoresistive element,
28, 29 and 30 are formed. A common terminal 27a is formed from the magnetic thin films 27 and 29, a terminal 28a is formed from the magnetic thin film 28, and a magnetic thin film 30 is formed.
Terminals 30a are respectively drawn from the terminals, terminals 27a are arranged side by side on the terminals 25a, and terminals 28a are windows 32e of the insulating film 32.
Is directly connected to the terminal 23a through the through hole 32f of the insulating film 32 and the terminal 30a is directly connected to the terminal 25a through the window hole 32f of the insulating film 32. Also,
The tip of each magnetic thin film 27, 28, 29, 30 is a window hole of the insulating film 32.
32a, 22b, 32c, 32d through the magnetic thin film 23, 24,
It is directly connected to the tips of 25 and 26. Therefore, the magnetic thin films 23 and 27 that are superposed on each other are connected in series between the terminals 23a and 27a, and the magnetic thin films 24 and 28 that are superposed on each other are the terminals.
Magnetic thin films 25 and 29 that are connected in series between 24a and 23a and are stacked on top of each other are connected in series between terminals 27a and 25a, and magnetic thin films 26 and 30 that are stacked on top of each other are connected in series between terminals 24a and 25a. It is connected. Except for the terminals 23a, 24a, 25a, and 27a, other portions are covered with a protective film, but the protective film is not shown. Each magnetic thin film is arranged so as to face the magnetic signal recording surface of the recording medium, and its longitudinal direction is orthogonal to the moving direction of the recording medium. Therefore, the phase difference of the resistance change of the magnetic thin films that are stacked and connected in series is zero.

Also in the case of this embodiment, since a plurality of magnetic films are superposed, there is an advantage that the amplitude of resistance change of the magnetic films superposed on each other becomes large.

(Effect of the Invention) According to the present invention, by arranging a plurality of magnetic films in a stacked manner via an insulating film and connecting them in series and arranging them on the substrate, all of the plurality of magnetic films can be the same in the recording medium Since the magnetic signal at the position is detected and the phase difference of the magnetic resistance change of the plurality of magnetic films arranged in layers is set to zero, the amplitude of the resistance change of the magnetic film as the detector is large and a large output can be obtained. . Also,
The magnetic films are directly connected on the substrate because some of the magnetic films are stacked on each other in series without interposing an insulating film and connected in series, so that the magnetic films are directly connected on the substrate. Since it is not necessary to newly provide a connecting means between the films outside the element, and it is not necessary to newly provide the connecting means on the substrate, there is an effect that the entire element can be made small, and Since the electric resistance of the means is not added in series, there is an effect that an accurate magnetoresistive effect can be obtained. Further, a plurality of magnetic films are provided in a direction perpendicular to the surface facing the recording medium, and
Since the magnetic resistance can be formed in a state of being extremely close to the recording medium, the magnitude of the magnetic signal applied to each magnetic film can be made large and almost equal, and the magnetic resistance has a high impedance and a large resistance change rate. An element can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing one aspect of the manufacturing process of the above embodiment, and FIG. 3 is a perspective view showing another aspect of the manufacturing process. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1, and FIG. 5 is line VV in FIG.
6 is a sectional view taken along line VI-VI in FIG. 1, FIG. 7 is a front view showing an example of a mode of use of the above embodiment,
FIG. 8 is a characteristic diagram showing the characteristic of resistance change obtained by the magnetoresistive element according to the above-mentioned embodiment in comparison with the conventional example, and FIG. 9 is a perspective view showing another embodiment of the present invention, FIG. Fig. 11 is a perspective view showing one embodiment of the manufacturing process of the above embodiment,
A sectional view taken along the line XI-XI in the figure, and FIG. 12 is a line XI in FIG.
A sectional view taken along line I-XII, FIG. 13 is a perspective view showing still another embodiment of the present invention, FIG. 14 is a perspective view showing one embodiment of the manufacturing process of the same embodiment, and FIG. 15 is the same manufacturing process. 16 is a sectional view taken along line XVI-XVI in FIG. 13, FIG. 17 is a sectional view taken along line XVII-XVII in FIG. 13,
FIG. 18 is a perspective view showing still another embodiment of the present invention, FIG. 19 is a perspective view showing one embodiment of the manufacturing process of the same embodiment, and FIG. 20 is a schematic view showing one example of a conventional magnetoresistive element. Front view, No.
FIG. 21 is a front view schematically showing another example of the conventional magnetoresistive element, FIG. 22 is a characteristic diagram showing resistance change characteristics obtained by the conventional magnetoresistive element, and FIG. 23 is an idea of the present invention. It is a characteristic diagram which shows the resistance change characteristic of the magnetoresistive element of this invention compared with the conventional magnetoresistive element for description. 3, 10, 15, 22 ... Substrate, 4, 6, 11, 13, 16, 18, 20, 23, 24, 25, 26, 27, 2
8, 29, 30 ... Magnetic film, 5, 12, 17, 19, 32 ... Insulating film, 9 ... Recording medium.

Claims (1)

[Claims] 1. A magnetoresistive element for detecting repetitive magnetic signals recorded on a recording medium by arranging them so as to face the recording medium, wherein a plurality of magnetic films and insulating films constituting the magnetoresistive element are recorded. The magnetic layers are alternately stacked on one surface of the substrate in a direction perpendicular to the surface facing the medium, and a part of the plurality of magnetic films are stacked without interposing the insulating film and connected in series to each other. By arranging on the substrate, all of the plurality of magnetic films simultaneously detect magnetic signals at the same position of the recording medium, and the phase difference of the magnetoresistance change of the plurality of magnetic films superposed is made zero. A magnetoresistive element characterized by the above.