JPH0799338B2 - Magnetic encoder - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic encoder that encodes and measures a position, a rotation angle, a rotation speed, and the like.

2. Description of the Related Art A conventional magnetic encoder using this type of magnetic disk has a structure as shown in FIGS. 4 and 5, for example, as disclosed in Japanese Patent Laid-Open No. 58-148914.

That is, the magnetic layer 4 is formed on the disk 3 attached to the rotating shaft 2 of the main body 1, a magnetic signal is recorded on the magnetic layer 4, and the magnetic sensor 5 arranged so as to face the disk 3 closely opposes the magnetic field on the rotating disk 3. The signal is read and the position, rotation angle, etc. are detected. Disk 3 in FIG.
The configurations of the magnetic layer 4 and the magnetic sensor 5 in FIG.

That is, the magnetic sensor 5 includes magnetoresistive effect elements M ₁ and M ₂ that generate a continuous signal of several tens to several thousand pulses per revolution and magnetoresistive effect element M ₃ that generates one reference signal per revolution. The magnetic material 4 is composed of a signal track 6 on which a continuous signal is recorded and a reproduction track 7 on which one reference signal is recorded.
It is formed from and. The signal track 6 and the magnetoresistive effect elements M ₁ and M ₂ face each other, and the reference track 7 and the magnetoresistive effect element M ₃ face each other. In FIG. 5, the disc 3 rotates about the center 10 of the disc, and λ is the recording signal wavelength in the signal track 6. When the disk rotates, the magnetoresistive element M ₁ , M ₂ ,
As shown in Fig. 6, the changes in the resistance of M ₃ are M _1R and M, respectively.
It becomes like _2R , M _3R .

In such a structure and operation, the magnetoresistive effect elements M ₁ and M ₂ are connected in series with each other as shown in FIG. 7, and the output terminal at the midpoint thereof is designated as e ₁ . In addition, the magnetoresistive effect element M ₃
9 and a resistor R are connected in series as shown in FIG. 9, and the output terminal at the midpoint is e ₀ , the voltages obtained from the respective output terminals e ₁ and e ₀ are continuous wavelengths λ shown in FIG. Signal output and 10th
The reference signal output is detected from the wavelength λ shown in the figure.

However, in the magnetic encoder configured as described above, the wavelength of the reference signal output e ₀ becomes longer than the wavelength λ of the continuous signal output e ₁ and the accuracy of the reference position detection becomes poor. was there. This is for the following reason.

In other words, since the continuous signal continuously records the magnetic signals of the S pole and the N pole, the magnetic flux does not spread due to repulsion from the adjacent magnetic pole, but the reference signal records only one set of the S pole and N pole. So
The magnetic flux easily spreads. Here, it is conceivable to shorten the recording wavelength of the reference signal, but this has a problem that the output becomes weak.

Means for Solving the Problems In order to solve the above problems, the present invention arranges circular magnetic reference tracks and circular magnetic signal tracks each having a gap in concentric circles and sets the gap between the circular magnetic reference tracks. A magnetic disk having a recording wavelength smaller than the recording wavelength recorded on the circular magnetic signal track and a detection element for detecting the magnetic flux of both tracks are provided, and the extension line of the boundary line between the circular magnetic reference track and the gap and the circular magnetic field. The extension lines of the detection elements for reading the reference tracks are oriented substantially at the center of the magnetic disk.

Action The action of this technical means is as follows. Since the width of the gap of the reference track is formed shorter than the recording wavelength recorded on the signal track, the reference signal output has a shorter wavelength than the continuous signal output, and the reference position detection accuracy is improved. By changing the shape of the gap, the rise and fall of the reference signal output can be made steeper, and a large reference signal output can be obtained.

Embodiment An embodiment of the present invention will be described with reference to the accompanying drawings. First
The main configuration of the embodiment of the present invention is shown in the drawing. 8 is signal track 6
The reference track is magnetized in a fixed direction. Other configurations are similar to those of the conventional example. When the disk 3 is rotated around the disk center 10 as a central axis, the magnetoresistive element M ₃ detects a location where no magnetic flux exists due to the gap 8 to obtain an output e ₂ . Similarly, a continuous signal pre-recorded on the signal track 6 is detected by the magnetoresistive effect elements M ₁ and M ₂ , and e ₃
You will get output like Since the gap 8 is shorter than the recording wavelength of the signal track 6 and the rising and falling edges are steep, the wavelength of the reference signal output e ₂ is shorter than the wavelength of the continuous signal output e ₃ , so the accuracy of detecting the complementary position is improved. To do. The extension line of the two boundary lines 9 between the gap and the magnetic layer and the extension lines of the magnetoresistive recording elements M ₁ , M ₂ , and M ₃ are directed toward the center 10 of the disk, whereby the magnetoresistive effect element is obtained. The boundaries are parallel to each other, and a steeper reference signal output can be obtained.

FIG. 3 shows another embodiment of the present invention in which the gap facing direction width W _g is narrower than the reference track width W _t , and a magnetic flux is concentrated in the gap portion to obtain a steeper reference signal.

It is also conceivable to separately arrange the magnetic film on the outer peripheral surface of the disk.

As described above, according to the present invention, the circular magnetic reference tracks and the circular magnetic signal tracks having the gaps are arranged concentrically, and the gaps between the circular magnetic reference tracks are recorded in the circular magnetic signal tracks. A magnetic disk smaller than the recording wavelength and a detection element that detects the magnetic flux of both tracks, and an extension of the boundary line between the circular magnetic reference track and the gap and an extension of the detection element that reads the circular magnetic reference track. Since the lines are oriented substantially to the center of the magnetic disk, the boundary line and the detection element are provided with the center of the magnetic disk as a reference, so the detection element and the boundary line pass in parallel easily and accurately. It is possible to detect the reference position because the detection element can obtain outputs from all parts of the boundary line almost at the same time. It is possible to provide a high-resolution magnetic encoder in which the accuracy can be increased and a steep rising and falling reference signal can be obtained, which is less likely to malfunction.

[Brief description of drawings]

FIG. 1 is a plan view showing a magnetic encoder according to an embodiment of the present invention, FIG. 2 is an output waveform diagram thereof, FIG. 3 is a plan view of essential parts of a second embodiment of the present invention, and FIG. 4 is a conventional example. FIG. 5 is a side view of the disk and the magnetic sensor, FIG. 5 is the same plan view, FIG. 6 is the same output waveform diagram, FIG. 7 and FIG. 9 are the same connection diagram, and FIG. 8 and FIG.
The figure is the same output waveform diagram. 6 ... Signal track, 7 ... reference track, 8 ... gap, 9 ... boundary line, 10 ... disk center.

Front page continuation (72) Inventor Kazuhiko Sugimoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-57-154014 (JP, A)

Claims (2)

[Claims] 1. A circular magnetic reference track and a circular magnetic signal track having a gap are arranged concentrically, and the gap of the circular magnetic reference track is smaller than the recording wavelength recorded on the circular magnetic signal track. A magnetic disk and a detection element for detecting the magnetic flux of each of the tracks, and an extension line of the boundary line between the circular magnetic reference track and the gap and an extension line of the detection element for reading the circular magnetic reference track. Magnetic encoders characterized by facing the center of each magnetic disk. 2. The width of the track facing the gap is narrower than the width of the circular magnetic reference track.
The magnetic encoder according to the item.