JPH09243404A - Encoder, code plate for encoder and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly and easily register a code plate and a rotary shaft when the code plate is mounted, and prevent the code plate from being mounted upside-down. SOLUTION: A hole 3a for a positioning pin positioning a code plate 3 to a rotary shaft of an encoder is formed in the code plate 3. The code plate 3 is positioned to the rotary shaft by the use of the positioning pins. An asymmetric arrangement pattern is preferred for the positioning pins on the code plate so that it can be distinguished whether the code plate is a front face or a rear face. The code plate 3 is thus prevented from being mounted in an inverted direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modular encoder mounted on a rotary shaft of a rotating device such as a motor and detecting the number of rotations and the rotation angle.

[0002]

2. Description of the Related Art An encoder is mounted on a rotary shaft such as a servo motor and detects the number of rotations and the rotation angle of the rotary shaft. The encoder is a disc (code plate) having a light-transmitting region and a light-shielding region formed in a predetermined pattern on the periphery, a light source for irradiating light to the pattern forming portion of the disc, and a light source that faces the light source with the code plate interposed therebetween. And an optical sensor that receives light transmitted through the code plate. The encoder usually has a signal processing circuit arranged on an electric board and outputs an electric signal indicating the rotational angle position of the code plate, that is, the rotational angle position of the rotary shaft based on the signal from the optical sensor.

[0003]

There are an incremental pattern and an absolute pattern as a pattern composed of a light-transmitting portion and a light-shielding portion formed on the outer peripheral portion of a code plate of an encoder. Since the incremental pattern is a pattern in which the light-transmitting portions and the light-shielding portions are alternately and repeatedly arranged, it may not be necessary to distinguish the front and the back of the code plate. However, in the absolute pattern, since the light-transmitting portion and the light-shielding portion are formed in a predetermined arrangement having no symmetry, it is necessary to properly attach the front and back sides of the code plate. However, it was easy to inadvertently attach the front and back sides to each other.

Further, there is a problem that it is not easy to align the code plate with the rotary shaft when attaching the code plate to the rotary shaft in the encoder. It is an object of the present invention to provide an encoder and a code plate, which can be accurately and easily aligned with a rotary shaft when the code plate is attached, and a manufacturing method thereof.

Another object of the present invention is to provide an encoder, a code plate, and a method for manufacturing the same that prevent the front and back of the code plate from being mistakenly attached.

[0006]

In order to solve the above problems, in the present invention, a disc-shaped code plate mounted on a rotating shaft and having a light transmitting region and a light shielding region of a predetermined pattern is formed. A light source arranged on the fixed part for irradiating the code plate with light; an optical sensor arranged on the fixed part for detecting an optical signal including pattern information transmitted through the code plate; and an output of the optical sensor. An encoder including an electric member that outputs an electric signal indicating a rotation angle position of the code plate based on the above, in the code plate, a positioning pin hole for positioning the code plate with respect to the encoder rotation shaft is provided, and a positioning pin Is used to position the code plate with respect to the rotation axis.

In order to properly attach the code plate to the front and back sides, the holes for the positioning pins of the code plate have different hole arrangement patterns when viewed from the front surface (front side) and the back surface. Differently, it may be provided at a plurality of asymmetrical positions.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the above encoder and code plate, the code plate may be made of various materials depending on the strength and durability requirements of the code plate. However, it is convenient to machine holes for positioning pins. Considering it, metal is desirable, and specifically, nickel clad (a copper plate sandwiched between nickel plates from both sides), stainless steel, or the like is preferable.

When all the positioning pin holes of the disc-shaped code plate are provided on the concentric circles, it is necessary to provide at least three holes in order to obtain the above-mentioned asymmetrical arrangement. However, it is possible to introduce asymmetry in the above sense by means of the two holes if the radial position on the code plate is displaced.

Further, when the above-mentioned light-transmitting portion of the code plate is formed as a through hole, it is preferable to simultaneously form the positioning pin hole in one step because the step is simplified. In this case, if the code plate is made of metal, the light transmitting portion through hole and the positioning pin hole can be formed by etching or pressing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a modular encoder 40 according to an embodiment of the invention mounted on a rotating device or motor 20. In FIG. 1, the inside of the modular encoder is partially shown in a sectional view. The modular encoder 40 of the present embodiment is often attached mainly to a servomotor.

The modular encoder 40 is attached to the rotary shaft of the motor, and comprises a rotor portion that rotates with the rotation of the motor rotary shaft and a fixed portion that is fixed to the main body of the motor.

First, the rotor portion will be described. The boss 1 is a member for attaching the code plate 3 to the rotary shaft 22 of the motor 20, and has a bore (lumen) 1a inside. The rotary shaft 22 of the motor 20 is received in the inner cavity and is fixed to the rotary shaft 22 by the screw 2. Shoulder 1b on top of boss 1
Is provided, and the code plate 3 is placed on the shoulder portion 1b. The code plate 3 has a pattern portion T (FIGS. 3 and 4) in which a light-transmitting portion and a light-shielding portion are alternately formed in a predetermined pattern on the outer peripheral portion thereof. The structure of the pattern portion in this embodiment will be described later with reference to FIGS. The code plate 3 is shown in FIGS.
As shown in FIG. 3, holes 3a for positioning pins are provided at predetermined positions. The shoulder 1b of the boss 1 has a screw hole 1c at a position corresponding to the hole 3a of the code plate 3. The code plate 3 is bonded to the shoulder 1b with the holes 3a for positioning pins and the shoulders 1b aligned, and the screws (or pins) 4 inserted (in this embodiment, screws are used for positioning the code plates). However, the present invention is not limited to this and may be a pin). A pressing ring 5 having a hole at a position corresponding to the hole 3a is adhered from above the code plate 3 so that the head of the screw 4 is received in the hole. The pressing ring 5 presses the code plate from above, plays a role of sinking the head of the screw 4, and the magnet 6
I support. The magnet 6 is bonded onto the pressing ring 5. The magnet 6 has a known magnetization pattern. The function of this magnet will be described later. The above part constitutes a rotor part that rotates together with the rotation shaft of the motor.

Next, the fixed portion will be described. The fixing member 7 is made of resin and has a generally annular shape.
a is formed. The protrusion 21 protruding from the motor body 25 is received in the bore 7a. The protrusion 21 has a diameter of 2
It has a stepped, almost cylindrical shape. The fixing member 7 is fixed to the protruding portion 21 of the motor body 25 with the screw 8.
An annular groove 23 is formed on the outer periphery of the protrusion, and the annular groove 23
An O-ring 24 is arranged inside and seals between the fixing member 7 and the motor body 25. A holding member 11 having a generally annular shape is attached to the fixing member 7 from above in FIG. A screw hole 7b is formed on the upper surface of the fixing member 7, and a metal washer 10 internally threaded is embedded in the hole 7b. The holding member 11 is fixed to the fixing member by a screw 9 penetrating the holding member and screwed into the washer 10. In FIG. 1, the electric board 12 is fixed to the holding member with screws 14 above the holding member.

FIG. 2 is a partial sectional view showing the motor and the encoder depicted in FIG. 1 from another angle (the direction in which FIG. 1 is rotated 90 degrees around the axis of the motor). The holding member 11 holds the light emitting element 30 on a part thereof. Light emitting element 30
Serves as a light source for irradiating the pattern portion T provided on the outer periphery of the code plate 3 with light. In this embodiment, a light emitting diode is used as the light emitting element 30. The light emitting element 30 emits light upward toward the pattern portion of the code plate 3. The electric board 12 at a position facing the light emitting element 30 with the code plate 3 interposed therebetween.
A light receiving element (optical sensor) 31 is attached on the top. In this embodiment, the light receiving element 31 is a photodiode. The light including the information of the pattern of the code plate is received by the light receiving element 31 by being emitted from the light emitting element 30 and transmitted through the light transmitting portion of the pattern portion of the code plate 3, photoelectrically converted and output as a detection signal. Then, based on the detection signal from the light receiving element 31, a processing circuit (not shown) provided on the electric substrate 12 outputs a signal indicating the rotation angle of the code plate, that is, the rotation angle of the rotation shaft 22.

On the other hand, a magnetic sensor 13 using an MR sensor (MR magnetoresistive effect element) or the like is attached at a position facing the magnet 6 on the electric substrate 12. Magnetic sensor 13
Outputs an electric signal according to the fluctuation of the magnetic field generated by the magnet 6 accompanying the rotation of the rotating shaft. Then, based on the electric signal, a processing circuit (not shown) provided on the electric substrate outputs a signal indicating the rotation speed of the rotating shaft.

The signals indicating the rotation angle and the rotation number are output to the outside of the encoder via the output signal line 15.

The rotor portion of the encoder described above,
Both the fixed parts are covered with a cover 17. An output line holder 16 for holding the above-mentioned output signal line 15 is provided on the outer surface of the cover. In addition, the cover 17 and the fixing member 7
The space between and is sealed by an O-ring fitted in an annular groove provided on the outer periphery of the fixing member.

Next, the code plate 3 of the encoder of this embodiment will be described in detail with reference to FIG. FIG. 3 is a plan view of the code plate 3. The code plate is made of nickel clad which sandwiches a copper plate from both sides with nickel plates. A pattern portion T is formed along the outer circumference of the code plate. Specifically, the pattern portion T includes three pattern tracks, that is, a track Ta of an incremental pattern, a track Tb of an absolute pattern (a pattern called M series), and a track Tc of an incremental pattern from the outside.
These patterns can be various and are not limited to the patterns of this embodiment.

Near the center of the code plate 3, holes 3a for inserting the positioning pins are formed at three positions. The positions of the holes 3a are arranged at asymmetrical positions such that the arrangement patterns differ depending on whether the code plate is viewed from the front or the back.

FIG. 4 shows another example of the code plate 3 according to the embodiment of the present invention. In this embodiment, the arrangement of the positioning pin holes 3a is different from that of the example of FIG. 3, and two holes 3a are provided at different radial positions (that is, not on concentric circles). By making the positions of the holes different from each other in the radial direction, only the two holes realize the above-mentioned asymmetry of the front and back surfaces. Other configurations are the same as those in FIG.

In the code plate 3 shown in FIGS. 3 and 4, each of the pattern tracks Ta, Tb, and Tc is a through hole formed in the code plate and transmits light from the light emitting element to reach the light receiving element. It includes a light-transmitting part that allows the user to do so. The light-shielding portion of the pattern track is composed of a portion of the code plate 3 where a through hole is not formed. When the code plate 3 is manufactured, the light transmitting portion as a through hole and the positioning pin hole 3a are simultaneously formed in one step by etching or pressing.

[0023]

According to the present invention, since the code plate of the encoder is provided with the hole for the positioning pin, the alignment with the rotary shaft can be accurately and easily performed when the code plate is attached.

Since the holes for the positioning pins of the code plate are provided at a plurality of asymmetrical positions so that the arrangement pattern of the holes is different when viewed from the front surface and when viewed from the back surface,
There is no risk of mistakenly installing the front and back of the code plate.

Further, when the transparent portion of the code plate is formed as a through hole, the hole for the positioning pin can be formed at the same time in one step, which simplifies the process. In this case, if the code plate is made of metal, the light transmitting portion through hole and the positioning pin hole can be formed by etching or pressing.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a state in which an encoder according to an embodiment of the present invention is attached to a motor.

FIG. 2 is a partial cross-sectional view of the encoder and the motor shown in FIG. 1 from different angles.

FIG. 3 is a plan view showing an example of a code plate of an encoder.

FIG. 4 is a diagram showing another example of the code plate of the encoder.

[Explanation of symbols]

 1 Boss 3 Code Plate 3a Positioning Pin Hole 4 Positioning Pin 6 Magnet 7 Fixing Member 11 Holding Member 12 Electric Board 20 Motor 22 Rotating Shaft 30 Light Emitting Element 31 Light Receiving Element

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuji Yamazaki 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (8)

[Claims] 1. A disc-shaped code plate mounted on a rotary shaft and having a predetermined pattern formed thereon, and a detector arranged on a fixed portion for reading a predetermined pattern of the code plate and detecting rotation information of the code plate. An encoder comprising: the encoder, wherein the code plate has a hole for a positioning pin for positioning the code plate with respect to the encoder rotation shaft. 2. The encoder according to claim 1, wherein the hole for the positioning pin of the code plate is a hole when viewed from the front surface and when viewed from the back surface so that the code plate is not installed upside down. An encoder, which is asymmetrically provided at a plurality of positions such that the arrangement pattern of the encoder is different. 3. The encoder according to claim 2, wherein three or more holes for the positioning pins are provided. 4. The encoder according to claim 2, wherein the code plate has a disk shape, and two holes for the positioning pins are provided at different radial positions in the disk code plate. Characteristic encoder. 5. A disc-shaped code plate mounted on a rotary shaft and having a light-transmitting region and a light-shielding region of a predetermined pattern, and a light source arranged on a fixed portion and irradiating the code plate with light. An optical sensor that is disposed in the fixed portion and that detects an optical signal including pattern information that has passed through the code plate, and an electric member that outputs an electric signal indicating a rotation angle position of the code plate based on the output of the optical sensor. A code plate for an encoder, comprising: a code plate having a hole through which a positioning pin for positioning the code plate with respect to the encoder rotation shaft is inserted. 6. The code plate according to claim 1, wherein the code plate is made of a metal material. 7. The code plate according to claim 6, wherein the predetermined pattern includes a light-transmitting region, and the light-transmitting region is a through hole penetrating the code plate. 8. The code plate for an encoder according to claim 7, wherein the through hole forming the translucent region and the hole for the positioning pin are simultaneously formed in one step. Manufacturing method.