JPS63171316A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To improve resolution by alternately arranging magnetic bodies with poles N and S on a position information plane and defining a prescribed spacing between the distal end sides of the adjacent magnetic bodies with the same polarity. CONSTITUTION:A rotary disk 5 is formed with position information 9 coaxially with a rotor shaft 2. The information 9 is alternately provided with magnetic bodies having poles N and S to form a circular pattern. The magnetic bodies have spacings l between the distal end sides of the adjacent bodies with the same polarity. The width of each magnetic body is set to 1/2l. Further, a waveform forming circuit board 6 is extended to the surface of the disk 5 across its circumference. A magnetoresistance element mount 6' is mounted on the extended portion of the board 6'. A plurality of magnetoresistance elements 7 are arranged on the element mount 6. At least (n) elements 7 are arranged in positions wherein the (m-1)-th (m=2, 3, 4...) distal end side as numbered from the first distal end side is determined by the accompanying expression. A signal indicative of a quotient obtained when the spacing l be tween the adjacent magnetic bodies with the same polarity is divided by 2n can be derived from the output of the elements 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to magnetic encoders.

[Conventional technology]

In a magnetic encoder, position information is formed concentrically on the surface of a moving body, such as a rotating disk, and this position information is formed by alternately arranging N-pole and S-pole magnetized bodies. A magnetic resistance element is arranged to be fixed to the rotating disk and facing the position information, and the number of the magnetized bodies is counted based on the output from the magnetic resistance element. The rotation angle or rotational speed is detected (see NIKKEI MECHANICAL 1984°1.16 plG8-113).

[Problem that the invention seeks to solve]

The finer the magnetized body on the surface of the rotating disk, which is positional information, can be formed, and the narrower the distance between adjacent magnetized bodies of different polarities, the higher the resolution of the encoder can be.

In general, a magnetic encoder forms a magnetized body by applying magnetization in the thickness direction of a rotating disk, and is characterized by being able to record at high density, but the density is also subject to restrictions in terms of manufacturing etc. The resolution of a magnetic encoder also had a limit. The present invention was made in view of these circumstances, and an object of the present invention is to provide a magnetic encoder that makes it possible to further increase the resolution. It is.

[Means for solving problems]

In order to achieve such an object, two of the present inventions are arranged such that N-pole and S-pole magnetized bodies are arranged alternately on the position information surface, and from the leading edge of one magnetized body to the leading edge of the next magnetized body of the same polarity. A movable body having a distance of 1.5 mm, and a magnetoresistive element fixed to the movable body and arranged in parallel in the arrangement direction of the magnetized body, and facing the magnetized body, each magnetoresistive element having a first The (m-1) (m ; 2 * 3 e 4...)th tip edge from the tip edge is located at the position 5m determined by the following equation (1) = m-5 (1+ -) (1) n However, 5= p-Q (P=1, 2...), at least n are arranged, and means for extracting a signal obtained by dividing the distance between the magnetized bodies by 20 from the output of each magnetoresistive element. It is what it is.

[Effect]

When configured in this way, each magnetoresistive element.

It becomes possible to obtain an output corresponding to the overlapping area of the magnetized body (either the north pole or the south pole) on the rotating disk facing them. The output of each magnetoresistive element is obtained as a signal close to a sine wave.

This sine wave has a phase shift for each magnetoresistive element. Therefore, by extracting a signal corresponding to this phase shift, for example, the first magnetoresistive element among each magnetoresistive element detects one N-pole magnetized object on the moving plate surface, and then detects the next adjacent N-pole. Until the magnetized object is detected, the remaining magnetoresistive elements, for example, N
It is possible to obtain (2n-1) signals corresponding to the division positions between the pole magnetized bodies.

〔Example〕

An embodiment of a magnetic encoder according to the present invention will be described below with reference to one drawing.

FIG. 2 is a cross-sectional view of a magnetic encoder according to the present invention. In the same figure, there is a rotor shaft 2 protruding from a cover 1, and this rotor shaft 2 is connected to a nut 3 in the cover 1.
．． It is supported by a bearing 4. This rotating disk 5 is configured to rotate together with the rotor shaft 2. As will be described later, on this rotating disk 5, position information is formed concentrically, and this position information is formed by alternately arranging N-pole and S-pole magnetized bodies. A wave-forming circuit board 6 is arranged on the snow surface of the rotating disk 5 (on the right side in the figure),
This waveform-shaped circuit board 6 is supported by the cover 1 and fixed to the rotating disk 5. Further, the waveform-shaped circuit board 5 is formed to extend across the outer circumferential portion of the rotary disk 5 to the surface of the rotary disk 5, and this extending portion includes a magnetoresistive element mount. 6 is installed. A plurality of magnetoresistive elements 7 are arranged in parallel on this magnetoresistive element stand 6, and this magnetoresistive element row faces the magnetized body row on the surface of the rotating disk 5.

The output of each of these magnetoresistive elements 7 is input to the circuit on the waveform shaping circuit board 6, and the output of the circuit is taken out to the outside of the cover 1 via a lead wire 8. ing.

As shown in a plan view of FIG. 3(a), the rotating disk 5 has position information 9 formed in a circular pattern coaxially with the rotor shaft 2. This positional information 9 indicates that as shown in the third part (1(b)) which is an enlarged view of B in Figure 1, the N-pole and S-pole magnetized bodies 10 are alternately arranged in parallel to form the circular pattern. This magnetized body 10 is
As shown in detail in FIG. 1(a), one magnetized body 10
They are arranged side by side with a short distance from the tip side of the next magnetized body 10 of the same polarity. And each magnetized body 10
11 (the side that coincides with the m film direction) is set to 1/2i.

The value of m can take a value determined as a minimum value based on various technical conditions in forming the magnetized body.

On the other hand, the arrangement of the magnetoresistive elements 7 is, for example, four, as shown in FIG. 1(b), with the first magnetoresistive element 7
The second magnetoresistive element 7B is arranged so that its tip side is spaced 1-Ω from the tip side of A, and the tip side is positioned 3-Ω apart from the tip side of the first magnetoresistive element 7A by 2To. The th magnetoresistive element 7C is arranged.

Furthermore, the fourth magnetoresistive element 7 is arranged so that its tip side is positioned 3-Q apart from the tip side of the first slit 7A.
D is placed.

In this embodiment, four magnetoresistive elements 7 are arranged. However, this number is set depending on the desired resolution. For example, the first magnetoresistive element 7A
The tip side of the (m-1) (m=2.3.4...)th magnetoresistive element from the tip side is determined by the following equation.

3 m = m-Q (1+ -) n Further, the width of each magnetoresistive element 7 is set to Q/2 similarly to the magnetized body 10 of the rotating disk 5.

Each magnetoresistive element 7 obtains the maximum output when completely facing the magnetized body 10 (either the N pole or the S pole), and as the rotating disk 5 rotates, a deviation occurs in the opposing position. In this case, an output corresponding to the overlapping area with the magnetized body 10 is obtained.

Next, the operation of the magnetic encoder configured in this way will be explained.

First, as shown in FIG. 4, magnetic resistance elements 7 are arranged in parallel.
are sequentially designated as 7A, 7B, 7C, and 7D, respectively, and the portions of the magnetized body 10 on the rotating disk 5 having the S pole on the surface facing the magnetoresistive element 7 are sequentially designated as IOA and I, respectively.
OB, IOC, IOD.

It is assumed to be 10E.

In such a state, each magnetoresistive element 7A, 7B
, 7G, and 7D, values corresponding to the output levels shown on the right side of FIG. 5(1) are obtained. In this example,
The output value is at the minimum level when the magnetoresistive element 7 is completely opposed to the N-pole magnetized body 10, and is at the maximum level when the magnetoresistive element 7 is completely opposed to the S-pole magnetized body 10.

From the minimum level to the maximum level, a value corresponding to the overlapping area of the magnetoresistive element 7 and the S-pole magnetized body 10 is obtained as an output value.

From this state, when the rotating disk 5 rotates (very slightly rotates) and comes to the position shown in FIG. changes as shown on the right side of FIG. 5(2).

Furthermore, as the rotating disk 5 rotates (also in this case, a very slight rotation) (Fig. 5 (3) to Fig. 5 (
8)), S pole magnetized body 10A for magnetoresistive element 7A
The superimposition of is canceled and the state returns to the same state as in FIG. 5(1). Until now, each magnetoresistive element 7A.

For 7B, 7G, and 7D, a sine wave of one wavelength is obtained as shown on the right side of Figure 5 (8).

If this is shaped into a waveform, a waveform as shown in Figure 6(a) will be obtained, and when the rising and falling signals are detected, a total of 8 signals will be obtained as shown in Figure 6(b). It will be done.

That is, when the rotating disk 5 rotates so as to move by a length of 4 on its 9 planes of position information, a signal corresponding to the 8 parts of a is obtained.

In the embodiment described above, the arrangement of the magnetoresistive elements 7 is determined based on, for example, the distance a between the tip sides of the S-pole magnetized body and the next adjacent S-pole magnetized body in the magnetized body 10 of the rotating disk 5. It is. However, it is not limited to this and may be determined based on 2Q.

Each magnetoresistive element 7A', 7B' with reference to 2a.

Figure 7 (a) (b) shows the case where 7G' and 7D' are arranged.
). As is clear from the figure, each magnetoresistive element 7
The magnetized bodies 10 of the rotating disk 5 corresponding to A', 7B', 7G', and 7D' are the 1st, 5th, 9th, and 13th magnetized bodies 10, respectively, and their positional relationship is shown in FIG.
a) It will be the same as shown in (b).

This means that each magnetoresistive element 7A' shown in FIG. 7(b)
, 7B', 7G', and 7D' are the respective outputs obtained from the respective magnetoresistive elements 7A and 7B in the case of FIG. 1(b).

These are the same outputs obtained from 7C and 7D.

Therefore, even with the arrangement shown in FIGS. 7(a) and 7(b), the effects of the present invention can be obtained.

Because of this, it is possible to arrange the magnetoresistive elements 7 based on 3Ω or 4Q, etc., and the general formula is (m-1) (m=2°3.4...)th from the first tip side. Letting Sm be the distance to the leading edge of , Sm=m-8(1+-) n , where 5=p-Ω (p=1.2.3...).

Furthermore, although the number of magnetoresistive elements 7 required is equivalent to half the minimum number of divisions, the number is not limited to this. By providing a plurality of magnetoresistive elements having the same function, even if one of them fails, the position detection means of the encoder can be driven without any problem.

Note that the present invention is a so-called pulse generator.

Needless to say, it is applicable to all types of incremental encoders or absolute encoders.

[Effects of the Invention] As is clear from the above description, according to the magnetic encoder according to the present invention, the resolution can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a magnetic encoder according to the present invention. FIG. 1(a) shows the arrangement of magnetized bodies formed on a rotating disk, and FIG. 2 is a sectional view showing the overall configuration of the magnetic encoder, FIGS. 3(a) and 3(b) are views showing details of the rotating disk of the magnetic encoder, and FIG. 4 is the rotating disk. 5(1) to 8) are explanatory diagrams showing changes in output from each magnetoresistive element as the disk rotates, and FIG. 6(a) (b) is an explanatory diagram showing an example of processing the output from each magnetoresistive element, and FIG. 7(a) (
b) is a block diagram showing another embodiment of the magnetic encoder according to the present invention. 5... Rotating disk, 7... Magnetoresistive element, 10... Magnetized body.

Claims (1)

[Scope of Claims] A moving body in which N-pole and S-pole magnetized bodies are alternately arranged on a position information surface, and there is a distance l from the tip side of one magnetized body to the tip side of the next magnetized body with the same polarity. , magnetoresistive elements fixed to the movable body, arranged in parallel in the arrangement direction of the magnetized body, and facing the magnetized body, each magnetoresistive element having a distance (m-1) from the first tip side. The position where the (m=2, 3, 4...)th tip edge is determined by the following equation (1) Sm=m・S(1+1/2n)...(1) However, S=p・l(p= 1, 2...), and at least n are arranged, and the spacing l between the magnetized bodies is 2 from the output of each magnetoresistive element.
A magnetic encoder comprising: means for extracting a signal divided into n parts.