JPH085409A - Encoder - Google Patents

Abstract

PURPOSE:To provide a compact encoder at low cost. CONSTITUTION:Regarding an encoder having an optically detecting part composed by arranging light transmitting parts 2a and light shielding parts 2b reciprocally to read out a bright and dark pattern 2 and a magnetically detecting part to read out a magnetic pattern, either the light transmitting part or the light shielding parts are made of a magnetic material, so that the bright and dark pattern 2 can be used also as a magnetic pattern and thus the number of the tracks of a desk 1 and the number of parts can be lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder, and more particularly to an encoder having an optical detection unit for reading a light and dark pattern and a magnetic detection unit for reading a magnetic pattern.

[0002]

2. Description of the Related Art FIG. 5 is a plan view of a conventional encoder, and FIG.
FIG. 6 is a side view of the encoder of FIG. 5.

A conventional encoder is a glass disk 101 mounted on a rotary shaft 104, and is formed on the upper surface of the disk 101 and has light-transmitting portions 102a and light-shielding portions 102b alternately arranged in the circumferential direction. A light / dark pattern 102 and a light source 105 arranged above the disc 101 and irradiating the disc 101 with light.
Is arranged to face the light source 105 via the disc 101, and receives light transmitted from the translucent portion 102a of the disc 101.
The detection unit 106, a magnetic pattern (rubber magnet) 103 fixed to the upper surface of the disc 101 and having an N-pole magnet 103a and an S-pole magnet 103b arranged in the circumferential direction, and the disc 101.
And a magnetic detector 107 for detecting the magnetic field of the magnetic pattern 103.

As shown in FIG. 6, the light-dark pattern 102 and the magnetic pattern 103 form concentric circles centering on the rotation axis 104, and the light-dark pattern 102 is located outside the magnetic pattern 103.

The light receiving / detecting unit 106 converts the transmitted light from the light transmitting unit 102a into an electric signal and detects the rotation angle of the rotating shaft 104 based on the signal.

The magnetic detector 7 detects the number of rotations and the direction of rotation of the rotating shaft 104 based on the detected magnetic field.

[0007]

In the conventional encoder, as described above, the magnetic pattern 103 of the rubber magnet is fixed to the upper surface of the disc 101, and the light and dark pattern 102 is arranged outside the magnetic pattern 103. So the disk 10
However, there is a problem that the outer diameter of No. 1 becomes large and the rotary encoder becomes large.

Further, the magnetic pattern 103 and the disc 101 are separate parts, which is one of the causes of increasing the number of parts and the cost.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an encoder which is small in size and low in cost.

[0010]

In order to solve the above-mentioned problems, an encoder according to a first aspect of the present invention provides a code plate having a light-dark pattern and a magnetic pattern in which a bright portion and a dark portion are combined, and the light-dark pattern. In an encoder provided with a first detecting means for reading and a second detecting means for reading the magnetic pattern, the light-dark pattern or the code plate is formed of a magnetic material, and the magnetic pattern is formed on the magnetic material. Was formed.

In the encoder of the second aspect of the invention, one of the bright portion and the dark portion is made of a magnetic material.

[0012]

As described above, by forming the light-dark pattern or the code plate in which the light portion and the dark portion are combined with each other by using the magnetic material,
The light-dark pattern or the code plate can also be used as a magnetic pattern, and the number of tracks and the number of parts on the code plate can be reduced.

[0013]

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

FIG. 1 is a plan view of an encoder according to an embodiment of the present invention, and FIG. 2 is a side view of the encoder of FIG.

A disc (code plate) 1 is mounted on the upper end of the rotary shaft 4. The disc 1 is made of a transparent glass material,
On the upper surface of the disc 1, a light-dark pattern 2 is formed in which light-transmitting portions (bright portions) 2a and light-shielding portions (dark portions) 2b are alternately arranged in the circumferential direction. The light-shielding portion 2b is formed of a magnetic material described later, and the light-dark pattern 2 also serves as a magnetic pattern.

As shown in FIG. 1, of the two tracks 8 and 9 centering on the rotation axis 4, the outer track 9 has a half circumference of a light-shielding portion 2b and a light-transmitting portion 2a formed by magnets of N poles. And are alternately arranged, and the light shielding portions 2b and the light transmitting portions 2a, which are formed of S-pole magnets, are alternately arranged on the remaining half circumference. Similarly, the light-shielding portions 2b and the light-transmitting portions 2a formed of N-pole magnets are alternately arranged on a half circumference of the inner track 8, and the light-shielding portions 2b and the light-transmitting portions 2b formed of S-pole magnets are alternately arranged on the other half circumference. The parts 2a are arranged alternately. However, the outer tracks 9 adjacent to each other in the radial direction of the disk 1
The polarity of the magnet on the inner side and the polarity of the magnet on the inner track 8 are different from each other.

As shown in FIG. 2, a light source 5 for irradiating the disc 1 with light is arranged above the disc 1. Below the disc 1, a light receiving / detecting unit 6 that receives the transmitted light from the light transmitting unit 2 a of the disc 1 is arranged to face the light source 5 via the disc 1. The light receiving / detecting unit 6 converts the transmitted light from the light transmitting unit 2a into an electric signal, and detects the rotation angle of the rotating shaft 4 based on the signal. The light source 5 and the light receiving / detecting section 6 constitute a transmission type optical detecting section (first detecting means).

Above the disc 1, a light-dark pattern 2 is formed.
A magnetic detection section (second detection means) 7 for detecting the magnetic field of the light shielding section 2b is arranged. The magnetic detection unit 7 detects the rotation speed and rotation direction of the rotating shaft 4 based on the detected magnetic field.

According to the encoder of this embodiment, the light-shielding portion 2b is formed of a magnetic material and the function of the light-dark pattern 2 as the magnetic pattern 3 is given. A rubber magnet is not required.), The outer diameter on the disc 1 can be reduced, and the dimension in the rotation axis direction can be shortened, so that the encoder can be downsized and the cost can be reduced. it can.

FIG. 3 is a plan view of an encoder according to another embodiment of the present invention, and FIG. 4 is a side view of the encoder of FIG.

The same parts as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted. In the above-described embodiment, the case where the disk 1 is formed of a transparent glass material and the magnetic material is attached to the upper surface of the disk 1 to form the light-dark pattern 2 which also serves as a magnetic pattern has been described. As shown in FIG. 3, the disk 11 itself is made of a magnetic material,
Alternatively, the transparent holes 12a may be provided at regular intervals along the circumferential direction to form the light-dark pattern 12 that also serves as a magnetic pattern.

According to the encoder of this embodiment, it is possible to obtain the same effects as the above-mentioned embodiments.

In each of the above-described embodiments, the case where the present invention is applied to the rotary encoder has been described. However, it may be applied to a linear encoder, and a transmission type optical detecting section is used as the first detecting means. Although the case where it is used is described, a reflection type optical detection unit may be used. In the case of the reflection type, the magnetic material attached to the upper surface of the disc serves as the reflection portion.

[0024]

As described above, according to the encoder of the invention described in claim 1, since the light-dark pattern or the code plate also serves as the magnetic pattern, the number of tracks and the number of parts on the code plate are reduced, The code plate can be made small, and miniaturization and cost reduction can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of an encoder according to an embodiment of the present invention.

FIG. 2 is a side view of the encoder of FIG.

FIG. 3 is a plan view of an encoder according to another embodiment of the present invention.

FIG. 4 is a side view of the encoder of FIG.

FIG. 5 is a plan view of a conventional encoder.

FIG. 6 is a side view of the encoder of FIG.

[Explanation of symbols]

 1 Disc 2 Bright / Dark Pattern 2a Light Transmitting Part 2b Light Blocking Part 5 Light Source 6 Light Receiving / Detecting Part 7 Magnetic Detection Part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Morita 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (2)

[Claims] 1. A code plate having a light-dark pattern and a magnetic pattern, which is a combination of a light portion and a dark portion, a first detecting means for reading the light-dark pattern, and a second detecting means for reading the magnetic pattern. In the encoder including means, the light-dark pattern or the code plate is formed of a magnetic material,
An encoder having the magnetic pattern formed on the magnetic material. 2. The encoder according to claim 1, wherein one of the bright portion and the dark portion is made of a magnetic material.