JP2929714B2 - Angle detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle detecting device used for detecting a minute rotation, and more particularly to an angle detecting device having a magnetoresistive element and a magnetic recording medium that repeatedly generates magnetic signals. About.

[Prior Art] As a conventional technique, as an example of forming a magnetoresistive element on a flat substrate, for example, as shown in Japanese Patent Publication No. There is a type in which magnetoresistive elements are connected in series to each other at a distance from each other, and an output is obtained from a connection portion between them.

[Problems to be Solved by the Invention] However, since the conventional angle detection device described above incorporates a magnetic detection unit formed of a ferromagnetic thin film and a magnetic recording medium, it is difficult to adjust the gap between them.
It has always been difficult to continuously produce structures with the same gap.

In addition, when the angle detector and the position detector are configured using the above-described magnetoresistive element, a resistor stripe formed by a ferromagnetic thin film having a film thickness of about 100 to 1000 Å is usually at least, It has a length of around 1 mm.

When the magnetized surface of the magnetic recording medium and the resistor pattern surface are arranged so as to face each other, a magnetic field of a magnitude sufficient to obtain a sufficient magnetoresistance effect is applied to the entire surface of the resistor surface having a length of 1 mm. To achieve this, it is necessary to adjust the distance between the magnetic recording medium and the magnetoresistive element surface to a distance of several tens of μm. However, theoretically, the magnetic field strength decreases as the distance between the surface of the magnetic recording medium and the surface of the resistor increases, and the distance λ between the NS poles increases.
When the distance is approximately λ to 1.5λ, the reproduction sensitivity is significantly reduced. For this reason, as λ decreases, the limit distance for obtaining re-positive sensitivity decreases,
It becomes difficult to adjust the gap between the surface of the magnetic recording medium and the surface of the resistor. Therefore, the magnetization pitch of the magnetic recording medium cannot be made finer than a certain degree, and as a result, there is a problem that the detection accuracy cannot be improved.

SUMMARY OF THE INVENTION In view of the above-mentioned disadvantages, it is an object of the present invention to provide an angle detecting device which can easily and reliably set a gap between a magnetic recording medium and a magnetoresistive element.

[Means for Solving the Problems] According to the present invention, first and second cylindrical magnetic recording media which have the same concentric axis and are magnetized in advance, and the first and second cylindrical magnetic recording media are provided. A cylindrical magnetoresistive element made of a ferromagnetic material interposed between the cylindrical magnetic recording media, wherein the first and second cylindrical magnetic recording media are relatively centered on the concentric axis. An angle detection device rotatably arranged and detecting a change in a magnetic field applied to the cylindrical magnetoresistive element relating to a relative position change of the first and second cylindrical magnetic recording media, and using the change as rotation angle detection data. Wherein the cylindrical magnetic resistance element has a fixed positional relationship with one of the first and second cylindrical magnetic recording media.

Further, according to the present invention, the first and second cylindrical magnetic recording media are arranged such that the first cylindrical magnetic recording medium is concentric with the second cylindrical magnetic recording medium inside the second cylindrical magnetic recording medium. The first cylindrical magnetic recording medium is rotatably arranged about an axis, and the first cylindrical magnetic recording medium is periodically magnetized on its cylindrical surface at an NS interval = λ (where λ is a real number), The cylindrical magnetoresistive element has a plurality of magneto-sensitive sections, and the plurality of magneto-sensitive sections are (1/1 /
2) An angle detection device characterized by being arranged at intervals of λ (n + 1) (where n is an integer) is obtained.

According to the present invention, there is provided an angle detecting device, wherein the cylindrical magnetic element has a high magnetic permeability material.

Further, according to the present invention, the cylindrical magneto-resistance element has two or more sets of magneto-sensitive elements arranged in series with each other.
More than one magnetic sensing element group is λ + nλ (where λ is a real number, n
(Integer is an integer), and a bridge circuit is formed, and the opposite sides of the bridge circuit are arranged substantially in parallel.

According to the present invention, there is provided an angle detecting device, wherein the distance between opposite sides of each bridge circuit is {(1/8) + (1/4) s} λ (where s is an integer). can get.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a top view of an angle detecting device according to an embodiment of the present invention, in which cylindrical magnetic recording media 1 and 3 rotate around a rotation axis 4. FIG. 2 is a partially enlarged view of FIG. 1. In FIG. 2, the elements of the cylindrical magnetic resistance element 2 and the cylindrical magnetic recording media 1 and 3 are represented linearly for easy understanding. When the distance between NS of the cylindrical recording medium 3 on the shaft side is λ, the distance between NS of the outer cylindrical magnetic recording medium 1 is expressed as 2λ. In the space between the two cylindrical recording media, there are places where the magnetic field is strengthened and places where the magnetic field cancels out. The magnetic fields generated from the two magnetic recording media have the same direction, the magnetic fields are strengthened, and the magnetic fields generated in the opposite directions cancel each other out. That is, in FIG. 2, in the position A, the reinforcement is made, and in the position B, the reinforcement is made.

In FIG. 3, stripes having a continuous return structure are arranged. By forming a bridge circuit by combining a stripe located at the position of the strong magnetic field and a stripe located at the position of the weak magnetic field, a change in the magnetic field applied to the cylindrical magneto-resistive element 2 is detected and used as rotation angle detection data.

[Effects of the Invention] As described above, the present invention combines a cylindrical magnetoresistive element in which a ferromagnetic thin film is formed on a side surface of a cylinder having the same rotation axis as a magnetic medium magnetically recorded on the cylinder. This has the effect that the gap between the magnetic recording medium and the magnetoresistive element can be easily set.

The magnetic recording media having the NS magnetization intervals of λ and 2λ have a strong magnetic field (the direction of the magnetic flux generated from the two magnetic recording media coincides) and a weak magnetic field (from the two magnetic recording media). (The direction of the generated magnetic flux is opposite). On the other hand, in the region where the directions of the magnetic fluxes coincide, if the gap between the cylindrical magnetoresistive element surface and either one of the magnetic recording medium surfaces is the same, when the configuration of the present invention is used, the conventional configuration is used. And a larger magnetic flux can be obtained. Therefore, when the gap is widened, a high reproduction output can be obtained, and the gap sensitivity characteristics can be improved. On the other hand, since the magnetic field sensed by the magnetoresistive element is the sum of the magnetic fields generated from the two magnetic recording media, as described above, the gap caused by the decrease in the magnetic flux due to the decrease in the NS interval becomes smaller. It is possible to prevent a decrease in sensitivity characteristics, and it is possible to select a magnetic recording medium with a small NS interval.

[Brief description of the drawings]

FIG. 1 is a top view of one embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present embodiment. 1 ... magnetic recording medium (NS = 2λ), 2 ... magnetic resistance element, 3 ... magnetic recording medium (NS = λ), 4 ... center axis, 10,
12,15,16 ... Input terminals, 11,13,14,17 ... Output terminals.

Claims (5)

(57) [Claims] A first and a second cylindrical magnetic recording medium having the same concentric axis and magnetized in advance, and a strong magnetic medium interposed between the first and the second cylindrical magnetic recording medium. A cylindrical magnetoresistive element made of a magnetic material;
The cylindrical magnetic recording medium is disposed so as to be relatively rotatable about the concentric axis, and the cylindrical magnetic resistance element is related to a relative position change of the first and second cylindrical magnetic recording media. An angular detection device that detects a change in a magnetic field over a range and generates rotation angle detection data, wherein the cylindrical magnetoresistive element is fixed to one of the first and second cylindrical magnetic recording media. An angle detection device having a positional relationship. 2. The angle detection device according to claim 1, wherein the first and second cylindrical magnetic recording media are the first and second cylindrical magnetic recording media.
Is disposed inside the second cylindrical magnetic recording medium so as to be rotatable about the concentric axis, and the first cylindrical magnetic recording medium is disposed on the surface of the cylindrical magnetic recording medium. ,
The magnetism is periodically magnetized at an NS interval = λ (where λ is a real number), and the cylindrical magnetic resistance element has a plurality of magnetically sensitive portions, and the plurality of magnetically sensitive portions is (1/1 / 2) An angle detection device which is arranged at intervals of λ (n + 1) (where n is an integer). 3. The angle detecting device according to claim 1, wherein said cylindrical magneto-resistance element has a high magnetic permeability magnetic material. 4. The angle detecting device according to claim 1, wherein the cylindrical magnetoresistive element has two or more magnetic sensing element groups arranged in series with each other, and the two or more magnetic sensing element groups. Is
An angle characterized by having elements arranged at intervals of λ + nλ (where λ is a real number and n is an integer) and also forms a bridge circuit, and opposite sides of the bridge circuit are arranged substantially in parallel. Detection device. 5. The angle detection device according to claim 4, wherein the bridge circuit is formed, and a distance between opposite sides of each bridge circuit is {(1/8) + (1/4) s} λ (where , S is an integer)
An angle detection device, characterized in that: