JPH07134047A - Multiple-rotation encoder - Google Patents

Abstract

PURPOSE:To facilitate assembly adjustment and reduce cost by increasing the detection gap between a permanent magnet and a magnetic sensor. CONSTITUTION:Permanent magnets 12a and 12b sealed on a retention member 8 formed by a magnetic body are adjacent in radial direction and the polarity of the end face of one permanent magnet 12a in contact with the upper surface of the retention member 8 differs from that of the end face of the other permanent magnet 12b in contact with the upper surface of the retention member 8 so that most of the magnetic flux discharged from an N pole of the end face of the permanent magnet 12b which is not in contact with the retention member 8 draw a large arc and are directed toward the S pole of the end face of the permanent magnet 12a which is not in contact with the retention member 8, thus increasing the detection gap between the permanent magnets 12a and 12b and a magnetic sensor 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-rotation encoder, and more particularly to a multi-rotation encoder for detecting the number of rotations, the direction of rotation, and the rotation angle within 360 ° of an electric motor.

[0002]

2. Description of the Related Art A multi-rotation encoder is mounted on a rotary shaft and has a pulse disc formed with a lattice pattern along the circumferential direction, a light source for irradiating the pulse disc with light, and a pulse disc. A light receiving element that is arranged to face the light source, receives the transmitted light from the pulse disc, and a rotation angle detection device that detects the rotation angle of the rotation axis based on the signal from this light receiving element,
A permanent magnet mounted on the rotating shaft via an annular holding member made of a non-magnetic material, a magnetic sensor for detecting the magnetic field of the permanent magnet, and the rotation speed and rotating direction of the rotating shaft based on a signal from the magnetic sensor. It is equipped with a rotation speed detection device for detecting the rotation speed (Japanese Patent Publication No. 4-76048).

FIG. 3B is a schematic diagram showing the state of the magnetic field of the permanent magnet. The permanent magnet 112 is fixed to the upper surface of the holding member 108. The holding member 108 is formed of a non-magnetic material, and the magnetic force line of the permanent magnet 112 draws a curve from the N pole to the S pole.

[0004]

However, the permanent magnet 1
Since the height h2 from the surface of 12 to the apex of the line of magnetic force is short, the detection gap between the magnetic sensor and the permanent magnet becomes narrow, and strict dimensional control is required, and there is a problem that assembly adjustment is difficult.

The present invention has been made in view of the above circumstances, and its object is to make it possible to widen the detection gap between the magnetic sensor and the permanent magnet, simplify the assembly and adjustment, and reduce the cost. It is to provide a multi-rotation encoder capable of

[0006]

In order to solve the above-mentioned problems, a multi-rotation encoder according to a first aspect of the present invention is mounted on a rotary shaft and has a lattice pattern having a light transmitting portion and a light shielding portion along the circumferential direction. And a light source for irradiating the disk with light, and a light transmissive portion of the disk. Light receiving means for receiving the transmitted light from the rotary shaft, a rotation angle detecting means for detecting a rotation angle of the rotary shaft based on a signal from the light receiving means, a holding member attached to the rotary shaft, and a holding member mounted on the holding member. A permanent magnet, a magnetism detecting means for detecting a magnetic field of the permanent magnet, and a rotation speed detecting means for detecting a rotation speed and a rotation direction of the rotating shaft based on a signal from the magnetism detecting means. The member is made of a magnetic material.

Further, in the multi-rotation encoder according to a second aspect of the present invention, the rotary shaft has an abutting surface that abuts the disk, and the disk has the abutting surface and the holding member. Is abutted against and pinched.

[0008]

As described above, since the holding member on which the permanent magnet is mounted is made of a magnetic material, a large detection gap between the permanent magnet and the magnetic detecting means can be secured.

If the disc is sandwiched between the holding member and the disc supporting surface of the rotary shaft, the holding member can also be used as a pressing ring for the disc.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a multi-rotation encoder according to an embodiment of the present invention.

The rotating shaft 1 is rotatably supported by bearings 3 and 4 attached to a housing 2. Rotating shaft 1
A collar 1a is provided on the outer periphery of the upper end of the rotary shaft 1, and a cylindrical boss 1b is provided on the upper end surface (disk support surface) 5 of the rotary shaft 1.

An annular pulse disc 6 is bonded to the upper end surface 5 of the rotary shaft 1. The pulse disc 6 is provided with a lattice pattern in which light-transmitting portions and light-shielding portions are randomly or alternately arranged along the circumferential direction.

The inner diameter of the pulse disc 6 is a cylindrical boss portion 1b.
When the pulse disk 6 is slightly larger than the outer diameter of the pulse disk 6 and is bonded to the upper end surface 5 of the rotary shaft 1, the boss portion 1b of the rotary shaft 1 escapes upward from the hole of the pulse disk 6.

A holding ring 7 is attached to the boss portion 1b of the rotating shaft 1, and the holding ring 7 holds the pulse disk 6 against the upper end surface 5 of the rotating shaft 1 as if pressed. When the adhesive force of the adhesive is reduced, the holding state of the pulse disk 6 is maintained by the holding ring 7.

A light emitting element 9 such as a light emitting diode is disposed below the pulse disk 6, and the light emitting element 9 faces a part of the lattice pattern of the pulse disk 6. Above the pulse disk 6, a light receiving element 10 such as a photodiode is provided.
Are arranged, and the light receiving element 10 and the light emitting element 9 face each other with the pulse disk 6 interposed therebetween. A fixed slit plate 11 is arranged between the light emitting element 9 and the pulse disk 6.

Light from the light emitting element 9 is fixed to the slit plate 11.
The light that has been irradiated onto the pulse disk 6 through the pulse disk 6 and is transmitted through the pulse disk 6 is received by the light receiving element 10 and photoelectrically converted, and a detection signal is output from the light receiving element 10. And light receiving element 1
Based on the detection signal from 0, the rotation angle of the rotation shaft 1 is detected by a rotation angle detection device (not shown) provided on the circuit board 15.

A holding member 8 formed of a magnetic material in an annular shape is adhered or pressure-bonded to the tip of the boss portion 1b of the rotary shaft 1. As shown in FIG. 2, four semicircular permanent magnets 12a to 12d are fixed to the upper surface of the holding member 8 in a state of being joined to one annular body. As this permanent magnet, one magnet may be magnetized as shown in FIG.

3A and 3B are sectional views taken along the line AA of FIG. As shown in FIG. 3A, the permanent magnets 12a,
12b are adjacent to each other in the radial direction, and the polarity of the end surface of one permanent magnet 12a in contact with the upper surface of the holding member 8 is different from the polarity of the end surface of the other permanent magnet 12b in contact with the upper surface of the holding member 8.

Above the permanent magnets 12a to 12d, as shown in FIG. 2, two magnetic sensors 1 having an opening angle of 45 °.
3, 14 are arranged. The magnetic sensors 13 and 14 are
Bias magnets 16a and 16b are provided, and permanent magnets 12a to
It is mounted on the circuit board 15 located above 12d. The magnetic information detected by the magnetic sensors 13 and 14 is a rectangular wave of 90 °, one pulse per one turn, and is stored in a reversible counter and a backup power supply (not shown) mounted on the circuit board 15. Based on the detected magnetic information, a rotation speed detection device (not shown) provided on the circuit board 15 detects the rotation speed and the rotation direction of the rotary shaft 1.

According to the multi-rotation encoder of this embodiment,
Permanent magnets 12a and 12b fixed on a holding member 8 made of a magnetic material are adjacent to each other in the radial direction and are in contact with the upper surface of the holding member 8, the polarity of one permanent magnet 12a and the holding member 8
Since it is different from the polarity of the other permanent magnet 12b in contact with the upper surface of the permanent magnet 1, as shown in FIG. 3 (a), most of the magnetic flux emitted from the N pole of the permanent magnet 12a draws a small arc.
Most of the magnetic flux emitted from the N pole of the permanent magnet 12b goes to the S pole of the permanent magnet 12a while drawing a large arc. Therefore, as shown in FIGS. 3 (a) and 3 (b), the height h1 from the surface of the permanent magnets 12a, 12b to the apex of the lines of magnetic force becomes longer than that of the conventional example, and as a result, the permanent magnets 12a, 12b and A large detection gap with the sensors 13 and 14 can be secured, assembly and adjustment can be simplified, and cost can be reduced.

Although it is conceivable that the holding member 38 is made of a non-magnetic material instead of the holding member 8 made of a magnetic material, as shown in FIG. 3 (c), as shown in FIG. The height h3 is only slightly increased as compared with the example, and it is not possible to secure a large detection gap before simplifying the assembly adjustment.

FIG. 4 is a vertical sectional view of a multi-rotation encoder according to another embodiment of the present invention. The same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted. Although the case where the press ring 7 is used has been described in the above-described embodiment, instead of this, as shown in FIG. 4, the boss portion 21b of the rotary shaft 21 is used.
Is provided on the outer circumference of the holding member 28, and an internal thread is provided on the inner circumference of the holding member 28. The holding member 28 is screwed to the boss portion 21b so that the holding member 28 presses the upper surface of the pulse disk 6 toward the support surface 5 side. You may

According to this embodiment, the holding member 28 is provided with the function of the holding ring 7 and the holding ring 7 is omitted, so that the encoder can be downsized.

If the housing 2 and the case 17 are made of a soft magnetic material, the magnetic field can be magnetically shielded from the disturbance magnetic field.

[0026]

As described above, according to the multi-rotation encoder of the present invention, since the holding member on which the permanent magnet is mounted is made of a magnetic material, a large detection gap between the permanent magnet and the magnetic detecting means can be secured. Assembling and adjusting is simplified, and the cost can be reduced.

Further, if the disc is sandwiched between the holding member and the disc supporting surface of the rotary shaft, the holding member can also be used as the disc retaining ring, so that the retaining ring can be omitted, and the encoder ring can be omitted. The size can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a multi-rotation encoder according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a relationship between a permanent magnet and a magnetic sensor.

FIG. 3 is a schematic diagram for explaining a magnetic flux of a permanent magnet.

FIG. 4 is a vertical sectional view of a multi-rotation encoder according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 6 pulse disc 8 holding member 9 light emitting element 10 light receiving element 12a to 12d permanent magnet 13 magnetic sensor 15 circuit board

Claims (2)

[Claims] 1. A disk, which is mounted on a rotary shaft and has a lattice pattern having a light-transmitting portion and a light-shielding portion formed in the circumferential direction, and arranged on one side of the disk. A light source for irradiating light on the disk, a light receiving means arranged on the other side of the disk for receiving the transmitted light from the light transmitting part of the disk, and a rotation axis of the rotating shaft based on a signal from the light receiving means. A rotation angle detecting means for detecting a rotation angle, a holding member attached to the rotating shaft, a permanent magnet attached to the holding member, a magnetic detecting means for detecting a magnetic field of the permanent magnet, and a magnetic detecting means And a rotation speed detection unit that detects the rotation speed and the rotation direction of the rotation shaft based on the signal of (3), and the holding member is formed of a magnetic material. 2. The rotating shaft has an abutment surface that abuts against the disc, and the disc abuts against the abutment surface and the holding member and is sandwiched therebetween. The multi-rotation encoder according to claim 1.