JPS59147213A - Magnetic rotary sensor - Google Patents

Abstract

PURPOSE:To contrive to enhance the accuracy of the titled sensor, by providing magneto-resistance elements to the entire periphery of the rotor of a magnetic recording medium by bridge connection so as to span a plurality of magnetic poles magnetized at constant pitches within two pitches to output a plurality of signals having different phases. CONSTITUTION:A magnetic drum 3 equipped with a magnetic recording medium having a magnetic patterns magnetized over the entire peripheral surface thereof at constant pitches is connected to the shaft 2 driven by a motor 1. On the other hand, a substrate 5 is fixed to a support table 4 and thin film like magneto-resistance elements 6 are formed on the surface thereof. Each magneto-resistance element 6 is opposed to the magnetic recording medium on the peripheral surface of the magnetic drum 3 so as to leave a constant interval 7 therebetween and four resistance elements at every eight cycles are combined as one set so as to span two magnetic poles and subjected to bridge connection to constitute two kinds of magnetic detection circuits each comprising seven sets. When the width of each magnetic resistance element 6 set to W and the mutual interval of the adjacent resistance elements is set to P, W>P is formed and, therefore, the magnetic resistance elements 61-68 are combined so as to be arranged in a two-layered structure through an insulating layer.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic rotation sensor, particularly a magnetic signal obtained from magnetic waves (□ turns) magnetized at equal intervals on a magnetic recording medium disposed around the entire circumference of a rotating body. The present invention relates to a magnetic rotation sensor that detects the rotation angle of a rotating body by reading it as a stain signal using a magnetic resistance element placed close to it.

[Prior art]

Generally, in this type of magnetic rotation sensor, one of the rotating bodies
The larger the number of output signals per rotation, the more accurate the measurement can be, and therefore K should be set by decreasing the pitch of the magnetic pattern magnetized on the magnetic recording medium.

However, when the pitch of the magnetic pattern is reduced in this way, the magnetic signal obtained from the pattern also becomes smaller, so it becomes necessary to reduce the spacing between the magnetic pattern and the magnetoresistive element that detects it. However, if this spacing is made small, there is a risk of sharp lashing between the magnetic recording medium and the magnetoresistive element, and there is a limit in terms of mechanical accuracy.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above circumstances, and its purpose is to enable highly accurate measurement without reducing the distance between the magnetic recording medium and the magnetoresistive element. The present invention provides a magnetic rotation sensor with the following characteristics.

[Summary of the invention]

In order to achieve the above objects, the present invention provides a method in which, if the spacing between the magnetic recording medium and the magnetoresistive element is increased, it is necessary to increase the magnetization pitch of the magnetic recording medium.
If this magnetization pitch is made large, the resolution becomes small, so a magnetic detection circuit made by increasing the magnetization pitch and combining multiple magnetoresistive elements is provided across two magnetic pole pitches, and the number of pulses with different phase differences is It is designed to detect.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a sectional side view of a main part of an example of a magnetic rotation sensor according to the present invention. In the figure, a magnetic drum 3 having a magnetic recording medium having a magnetic pattern magnetized at a constant pitch λ over the entire circumference is connected to a shaft 2 driven by a motor 1. Further, a substrate 5 is fixed on a support base 4 fixed to the housing of the rotating body, and a thin film-like magnetoresistive element 6 is formed on the surface of this substrate 5. It faces the magnetic recording medium on the circumferential surface of the magnetic drum 3 with a constant distance 7 therebetween.

FIG. 2 shows an example of a combination of the magnetic drum 3 and the magnetoresistive element 6. In the figure, the arrow indicates the rotation direction of the magnetic drum 3, and the magnetic track 3 formed on the magnetic drum 3 is composed of a plurality of N-8 magnetic poles.
Magnetoresistive elements 61 to 614161' to 614' are arranged at a ratio of 14 to 1 magnetic pole pitch λ in the rotation direction A of a.
are arranged respectively. These magnetoresistive elements 61 to 6t4. ef~617 spans 2 magnetic poles of N-8 magnetic poles that are arranged in series, and connects 4 magnetic poles every 8 magnetic poles to 1.
The magnetoresistive elements 6116716141 are combined as a set and connected in a bridge as shown in FIGS.
A magnetic detection circuit 6A consisting of 67' and magnetic resistance elements 62+6s+6f.

Seven sets of magnets 6B and qi detection circuits 6B are constructed in the same manner.

In such a configuration, when the magnetic drum 3 is rotated, the magnetic field applied to the magnetoresistive element 6 changes periodically in accordance with the magnetic pattern magnetized on the magnetic recording medium. As a result, there are seven sets of magnetic detection circuits 7A.

Since the electrical resistance of 7B, . . . 1 changes periodically, by shaping the current flowing through these magnetic detection circuits 7A, TB, . (g)
As shown by K, output signals of seven types of pulse waveforms with different phases are obtained.

In this case, since the pitch of the magnetic pattern is 2λ, the period of the obtained output signal is also 2λ, but the seven sets of magnetic detection circuits 7A, 7B, . . . Since they are arranged at a pitch of 2λ/8 along the line, eight-phase output signals with a phase shift of approximately 225° are obtained. In this case, seven sets of magnetic detection circuits 7A
, 7B, . As shown in figure (a), each magnetoresistive element 611-621631641651661
It is possible to do this by arranging and combining 67168 in a two-layer structure with an insulating layer 8 in between, and as shown in FIG.
Since it is possible to alternately arrange and combine 6g+67t6s so as to be connected in parallel to the lead portion 9, it is easy to form a structure with the phase difference accurately matched.

Rotation sensors generally used in machine tools, etc.
Approximately 5000 ppr (p
pulse per revolution), the distance T between the magnetic drum 3 and the magnetoresistive element 6 is approximately 0.2
mm condition is required. Then, about 5
When magnetizing 000pPr, the magnetization pitch is approximately 31.41
1 m, it is extremely difficult to set the interval I to about 0.2 trm.

Therefore, according to the above configuration, the magnetization pitch λ is set to about 126μ.
By outputting an 8-phase output signal as m (at this time, the phase difference between each phase is 180/7 = 22.5°), even if the interval T is about 0.2 mm, the output signal of about 20 Gauss is It became possible to detect and output magnetic fields. In addition, since it is necessary to properly control the phase difference of each output signal, in order to always maintain the correct phase difference or the order of the 7-phase output, two magnetic poles are used as explained in Figures 2 and 3. Bridge detection type magnetic detection circuit 7 inside the pitch
By arranging A, γB, . . . , the phase difference can be accurately controlled. In this case, since it is a 7-phase output, if 14 magnetic detection elements 61 to 614 are arranged within one magnetic pole pitch λ, the pitch between each element is about 15.
It becomes 7μ. On the other hand, in order to improve the detection sensitivity of the magnetoresistive element 6 in a low magnetic field, the pattern width of the magnetoresistive element 6 is set to about 1
Since the thickness is required to be 5 μm or more, Fig. 4(a), (
This can be easily realized by forming the magnetoresistive elements 61 to 67 into a two-layer structure in which they are alternately arranged in parallel as described in b).

In the above-mentioned embodiments, a bridge detection type magnetic detection circuit is provided within two magnetic pole pitches, but the present invention is not limited to this, and a differential detection type magnetic detection circuit is provided within one magnetic pole pitch. Of course, even if a magnetic detection circuit having a three-terminal configuration is provided, the same effect as described above can be obtained.

Further, in the above-mentioned embodiments, the case where the magnetic recording medium is provided on the magnetic drum is explained, but the present invention is not limited to this, and the present invention can be similarly applied to the case where a magnetic disk is used, for example. It goes without saying that this effect can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, measurement accuracy can be improved without reducing the distance between the magnetic recording medium and the magnetoresistive element, that is, without being constrained by mechanical processing conditions or assembly conditions. , an extremely excellent effect of enabling high resolution can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional configuration diagram of essential parts showing an example of a magnetic rotation sensor according to the present invention, Fig. 2 is a plan view showing an example of a combination arrangement of a magnetic drum and a magnetoresistive element, and Figs. 3 (a) and (b). FIG. 4(a) is a diagram showing an example of a magnetic detection circuit. (b) is a cross-sectional view and a plan view of essential parts showing an example of the arrangement of magnetoresistive elements, and Figs. 5 (a) to (g) are output signals obtained when using the arrangement examples of Figs. 2 and 3. FIG. 1--Motor, 2--Shaft, 3--Magnetic drum, 4--Support stand, 5--Substrate, 616
1~614*61~614... Magnetoresistive element, 6A
, 6B...magnetic detection circuit, T...interval, 8...
...Insulating layer, 9...Lead part. Agent Patent Attorney Akio Takahashi Figure 4 (0) (b) Figure 5

Claims (1)

[Claims] 1. A magnetic recording medium having a plurality of magnetic poles provided around the entire circumference of a rotating body and magnetized at a constant pitch, and a magnetic recording medium disposed near the rotating body to face the magnetic recording medium. and a magnetoresistive element that detects a periodic magnetic field caused by the magnetic pattern as a periodic change in electrical resistance, wherein the magnetic rotation sensor includes a magnetoresistive element that bridge-connects the magnetoresistive element across two pitches of the magnetic poles. A magnetic rotation sensor comprising a detection circuit and outputting multiple signals with different phases. 2. The magnetic rotation sensor according to claim 1, wherein the magnetic resistance elements constituting the magnetic detection circuit are arranged in multiple layers in the direction of the magnetic poles. 3. The magnetic rotation sensor according to claim 1, wherein the magnetic resistance elements constituting the magnetic detection circuit are alternately connected in parallel in both directions via lead portions.