JPH01233319A - Rotational position detector - Google Patents

Abstract

PURPOSE:To obtain a sinusoidal output by a simple construction and a simple adjusting method, by a method wherein a permanent magnet magnetized in the same direction as the axis of rotation of a gear formed of a magnetic material is disposed on the axis of rotation of the gear. CONSTITUTION:A permanent magnet 2 magnetized in the same direction as the axis of rotation of a gear 1 formed of a magnetic material and having a large number of magnetic pole teeth is disposed on the axis of rotation of the gear 1. This permanent magnet 2 gives the gear 1 a periodical change in the direction of a magnetic field. A magnetism-sensitive element 4 formed on a substrate 3 detects the periodical change in the direction of the magnetic field in the vicinity of the magnetic pole teeth of the gear 1. This magnetism- sensitive element 4 is connected to a constant current source 7, a fixed resistor 8, an output terminal 9 and a ground 10 through terminal parts 5 and 6. This constitution enables the attainment of a sinusoidal output at the output terminal 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetoresistive element having a magnetoresistive effect, which is used for detecting the rotation angle and rotation speed of a rotating object.
Hereinafter, it will be abbreviated as MR element. ) is related to a rotational position detection device using

Conventional technology A conventional rotational position detection device of this type is shown in FIG.

The configuration was as shown in B. Figure 3 is a plan view,
Figure B is a sectional view taken along the line B--B of Figure 3.

Now, the conventional rotational position detection device uses a rotating gear 2.
The detecting section 33 detects the rotational position of the substrate 2, which has a magnetically sensitive section 26 and terminal sections 27 and 28 formed on its surface.
6 and a permanent magnet 24 having the role of supplying a bias magnetic field. On the other hand, the gear 23 includes a large number of tooth-shaped irregularities (hereinafter referred to as magnetic pole teeth) made of a magnetic material on the surface facing the detection part 33.

Now, the magnetic sensing part 26 is connected to the terminal part 27 as shown in FIG.
．． Through 28, an external constant current source 29, a fixed resistor 30,
The gear 23 is connected to the ground 32 and the output terminal 31.
It is generally known that when the motor rotates at a constant speed, a sine wave-like output having the same period as the pitch period of the magnetic pole teeth of the gear 23 is obtained from the output terminal 31. This is a permanent magnet 24
The generated magnetic field is influenced by the uneven shape of the magnetic pole teeth of the gear 23 and is periodically bent, causing the magnetic field to be generated by the magnetic sensing part 26 of the detection part 33.
This is to generate a component in the magnetic sensing direction (±× force direction) against A sine wave-like output appears.

This periodic sine wave-like output was subjected to electrical signal processing to detect the rotational position of the gear.

(For example, Japanese Unexamined Patent Publication No. 155917/1982) Problems to be Solved by the Invention In such a conventional configuration, the permanent magnet that supplies the bias magnetic field to the magnetically sensitive part 26 and the magnetically sensitive part 26 are formed. A substrate 25 is bonded thereto. Therefore, in order to obtain a sine wave-like output from the output terminal 31, there is a problem in that the adjustment of the distance and angle between the gear 23 and the detection section 33 is very delicate and difficult.

The present invention solves these problems, and provides highly accurate rotational position detection with a wide range of applications that provides a sine wave-like output with a simple configuration and simple adjustment method without increasing the number of parts. The purpose is to provide a device.

Means for Solving the Problems In order to solve these problems, the present invention arranges a permanent magnet magnetized in the same direction as the rotation shaft on the rotation shaft of the gear, and applies a bias magnetic field to the magnetic sensing part. The permanent magnet that was attached to it has been removed.

With this configuration, a permanent magnet placed on the rotating shaft of the gear applies a magnetic field to the entire gear, and the direction of the magnetic field changes periodically in the vicinity of the magnetic pole teeth in synchronization with the unevenness of the gear. Then, periodic changes in the direction of this magnetic field are detected by a magnetic sensing section formed on the substrate. As a result, since the magnetic field is applied uniformly to the entire gear, a sine wave-like output can be easily obtained from the output terminal.

Embodiment FIG. 1 is a structural diagram of a rotational position detecting device according to an embodiment of the present invention, in which FIG. 1 is a plan view and FIG. In Fig. 1, 1 is a gear having a large number of magnetic pole teeth made of magnetic material, and 2 is a permanent magnet that gives periodic changes in the direction of the magnetic field to the gear 1, and is magnetized in the same direction as the rotation axis of the gear 1. and is placed on the gear 10 rotation axis. Reference numeral 4 denotes a magnetic sensing part that detects periodic changes in the direction of the magnetic field near the magnetic pole teeth of the gear 1, and is formed on the substrate 3. It is also assumed that the magnetic sensing section 4 is connected to a constant current source 7, a fixed resistor 8, an output terminal 9, and a ground 1o through terminal sections 6, 6, as shown in FIG.

With this configuration, the permanent magnet 2 placed on the rotating shaft of the gear 10 causes a periodic change in the direction of the magnetic field near the magnetic pole teeth of the gear 1, and this change is transferred to a magnetoresistive element having a magnetoresistive effect. A sinusoidal waveform output is obtained at the output terminal 9 by detection by the detection unit 11 consisting of the following.

FIG. 2 shows another embodiment of the present invention, in which FIG. 2 M is a plan view and FIG. 2 B is a front view. In FIG. 2, 12 is a gear having a large number of magnetic pole teeth made of magnetic material, and 13 is a gear 1.
A permanent magnet that applies a magnetic field to the gear 2 is magnetized in the same direction as the rotation axis of the gear 12, and is placed on the rotation axis of the gear 12. Reference numeral 16 denotes a magnetic sensing part that detects periodic changes in the direction of the magnetic field near the magnetic pole teeth of the gear 12, and is formed on the substrate 14. Further, it is assumed that the magnetic sensing section 16 is connected to a constant current source 18, a fixed resistor 19, an output terminal 20, and a ground 21 through a terminal section 15.16, as shown in FIG. 2B.

With this configuration, similar to the real layer side shown in FIG. By detecting with the detecting section 22 made of a magnetoresistive element having the effect, a sinusoidal waveform output can be easily obtained at the output terminal 2o.

Effects of the Invention As described above, in the present invention, a permanent magnet made of a magnetic material and magnetized in the same direction as the rotation axis of the gear is placed on the rotation axis of the gear, and a uniform magnetic field is applied to the entire gear. , which produces periodic changes in the direction of the magnetic field near the magnetic pole teeth with the same period as the increments of the magnetic pole teeth. Therefore, by detecting a change in the direction of the magnetic field using a magnetoresistive element having a magnetoresistive effect, a sine wave-like output can be easily obtained at the output terminal. In this case, since the detection section does not include a permanent magnet, the mounting interval and angle between the gear and the detection section can be easily adjusted. Furthermore, since the detection section does not include a permanent magnet, the size of the detection section can be reduced. Therefore, it is also possible to reduce the size of the rotational position detection device in the circumferential direction.

[Brief explanation of the drawing]

Figures 1 and B are plan views and sectional views of essential parts of a rotational position detection device according to one embodiment of the present invention, and Figure 2 and B are main parts of a rotational position detection device according to another embodiment of the present invention. a plan view and a front view of
FIGS. 3A and 3B are a plan view and a sectional view of main parts of a conventional rotational position detection device. 1.12...Gear, 2,13...Permanent magnet, 3゜14...Substrate, 4,15...
・Magnetic sensing part, 6,6゜16.17...Terminal part, 7
, 18... Constant current source, 8゜19... Fixed resistor, 9, 20... Output terminal, 10.21
......Grounding, 11.22...Detection section. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A rotating gear made of a magnetic material and having tooth-like unevenness on its circumference, a magnetoresistive element having a magnetoresistive effect for detecting the tooth-like unevenness of the rotating gear, and a permanent magnet that applies a magnetic field to the rotating gear. A rotational position detecting device comprising: a rotating shaft direction of the rotating gear and a magnetization direction of the permanent magnet arranged on the rotating shaft of the rotating gear so that the direction of the rotating shaft of the rotating gear matches the direction of magnetization of the permanent magnet.