JPH0352566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic rotary encoder that is easy to manufacture, adjust, etc.

In recent years, rotary encoders have been used to accurately measure the rotation speed and rotation angle of servo motors used in NC machine tools. As is well known, there are two types of encoders: incremental type and absolute type, which allows the initial position at startup to be determined. In an absolute type magnetic rotary encoder, first, the rotating magnetic disk is divided into N = ²ⁿ fan-shaped segments according to the required accuracy, and each segment is determined by the presence or absence of n magnetic tracks. This is determined based on the results of an investigation using an element that detects magnetic flux. For example, if a resolution of 4 is required, use the number of rotating magnetic disks (DISK) shown in Figure 1, 4=
2 It is divided into ^two segments (SEG), and each segment is determined by the presence or absence of two magnetic tracks (MTR), as shown in FIG. Maybe again
1024=10 If a resolution of ¹⁰ is required, the presence or absence of 10 magnetic tracks is checked for each segment so that each of the 1024 segments can be identified. As in the case of ordinary magnetic tape, the magnetic track is formed by magnetizing NSN...SNS in the longitudinal (circumferential) direction of the magnetic track, as shown in FIG. In a normal magnetic tape recorder, the playback head is in contact with the tape surface, but in a magnetic rotary encoder, the frictional force generated in the contact area is avoided, and the magnetic field detection element and the rotating magnetic disk are moved a minute distance, for example, 50 μm. Release. The magnetic field detection element, or head, most widely used in magnetic tape recorders, etc., uses a coil wound around a magnetic core that passes leakage magnetic flux from the tape, and utilizes the electromotive force generated in response to changes in magnetic flux. , requires a relatively complicated manufacturing process, is large in size and heavy, and if a magnetic rotary encoder is provided with 10 tracks and uses 10 heads to obtain a resolution of 1024, for example, it is large and expensive. Problems arise, such as that the adjustment is not easy.

An object of the present invention is to provide an absolute type magnetic rotary encoder that is free from such problems and is easy to manufacture, adjust, etc.

In order to achieve the above object, in the present invention,
All of the plurality of magnetoresistive elements capable of detecting leakage magnetic flux from the plurality of magnetic tracks provided on the rotating magnetic disk are placed on the same substrate surface at a small distance from the surface of the rotating magnetic disk. It was decided that they would be arranged side by side on a projection onto the substrate surface of one diameter.

FIG. 4 is an explanatory diagram of the relative positions of the magnetic track MTR and the magnetoresistive element MRD in the present invention. As shown in the figure, the magnetoresistive element MRD and the surface of the rotating magnetic disk on which the magnetic track MTR is provided are separated by a small distance g, for example, 50 μm. Figure 5 is a perspective view of one embodiment of the present invention. In the figure, DISK is a rotating magnetic disk, MRD is a magnetoresistive element, BPL is a substrate, BND is a bonding pad, and LW is a lead wire connected to the bonding pad. It is. 6th
The figure shows an embodiment of the present invention, in which 10 sets of magnetoresistive elements 1 are placed on a single glass or ceramic substrate 4.
Shows the state in which it is placed. The magnetoresistive element 1 has an elongated inverted U shape and is formed of thin wires made of permalloy film, and two elements 1 forming a set are connected by a wide signal line 2 made of permalloy film. That is, first, a magnetoresistive element and a signal line are formed using a permalloy film on the substrate 4. The film thickness is approximately 500 Å. A power supply line 3 made of an aluminum film or the like and connected to both ends of each pair of elements is formed thereon via an insulating film. 5 is a signal line end bonding pad, and 6 is a power line bonding pad, one of which is grounded and the other connected to the power source. The left and right distance between the left and right magnetoresistive elements 1, which form a pair of left and right magnetoresistive elements 1, of the signal line 2 is the magnetic track magnetization pitch (NS distance)
If it is approximately half of that, each time one magnetized pitch of the track passes through this pair of elements, an unbalance in the resistance of the left and right elements will occur, and the potential of the signal line and therefore the pad 5 will fluctuate. It is detected that the rotating magnetic disk has rotated by one resolution unit. From FIG. 5 and FIG. 6, it can be seen that the signal line end bonding pad 5 and the power line bonding pad 6 are placed on the same substrate 4 (at an arbitrary position), respectively, on the magnetoresistive element 1 and the signal line 2. It can be seen that the process of making the power line 3 and the process of making the power supply line 3 can be easily made together. If something like the head of a conventional magnetic tape recorder is used, a magnetic core and windings are required to detect the magnetic field, and the head, wiring, and bonding pads are all included as in the case of the present invention. It cannot be made using a simple process. In addition, in the present invention, since multiple magnetoresistive elements are on the same substrate, adjustments such as making the minute distance between each element and the surface of the rotating magnetic disk uniform to a predetermined value, for example, 50 μm, and adjusting the phase (azimuth), etc. can be performed simultaneously. It can be done easily. In addition, permalloy film,
The aluminum film can be easily formed by techniques such as vapor deposition or sputtering and photoetching, or in some cases by a printing method. The small symbol RSZ on the right side of FIG. 6 is the actual size of the substrate 4.

As explained above, according to the present invention, it is possible to obtain an absolute type magnetic rotary encoder that is extremely simple and easy to manufacture, adjust, etc.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining the absolute type magnetic rotary encoder, and FIG. 4 is a diagram for explaining the relative position of the magnetic track and the magnetoresistive element in the present invention.
FIG. 5 is a perspective view of an embodiment of the present invention, and FIG. 6 is a diagram showing a plurality of magnetoresistive elements arranged on the same substrate and wiring to each element according to the present invention. SEG...segment, MTR...magnetic track,
MRD...magnetoresistive element, DISK...rotating magnetic disk, BPL...substrate, BND...bonding pad,
LW... Lead wire, 1... Magnetoresistive element, 2... Signal line, 3... Power line, 4... Board, 5... Signal line end bonding pad, 6... Bonding pad for power line.

Claims (1)

[Claims] 1. A rotating magnetic disk in which a plurality of magnetic tracks are formed concentrically and have magnetized regions having fine magnetized pitches alternately magnetized in opposite directions and non-magnetized regions in the circumferential direction; There are a plurality of sets of magnetoresistive elements that correspond to magnetic tracks and detect leakage magnetic flux from the magnetic tracks, and in the set of magnetoresistive elements, 1/2 of the fine magnetized pitch is present.
magnetoresistive elements are arranged at intervals of A magnetic rotary encoder characterized by being arranged in a.