JP2004125734A - Manufacturing method of slit plate of optical rotary encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a metal slit circular disk which is high in strength and high in stiffness and formed with a precise slit by etching. <P>SOLUTION: The metal slit disk 5 for an optical rotary encoder is manufactured as follows: a disk 1 of Cu alloy is Ni plated 2, 3 on both its faces, and the Ni plated disk is etched from both the sides for forming a slit 4. The thicker the disk 1 is made, the larger the strength and stiffness of the slit disk 5 becomes. The etching speed of the Ni films 2, 3 are slower than that of the Cu alloy. Therefore, slit apertures 2a, 3a with a high precision can be formed on the Ni films 2, 3. The slit shape is limited by the slit apertures 2a, and 3a. Thereby the slit disk 5 of a high strength and high stiffness provided with the precise slit 4 can be obtained. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a metal slit plate used for an optical rotary encoder.
[0002]
[Prior art]
As is well known, an optical rotary encoder is composed of a slit disk in which slits are formed at a predetermined pitch in a circumferential direction, and a light-emitting element and a light-receiving element which are arranged to face each other with a slit forming position of the slit disk therebetween. It is used to detect information such as the rotation speed and the rotation position of the rotating member. The slit disk is generally manufactured by etching a thin metal plate of about 30 to 50 microns, for example, a stainless steel disk to form slits.
[0003]
[Problems to be solved by the invention]
However, since the slit disk is manufactured using such a thin metal plate, the slit disk is liable to be bent or to have residual distortion. For example, distortion tends to occur when the slit disk is fixed to a rotating shaft or the like. If distortion remains in the slit disk, an abnormality may occur in the detected signal waveform. Further, a thin and lightweight slit disk tends to generate resonance during high-speed rotation driving, and when the slit disk enters a resonance state, an abnormality in a detection signal or the like is also caused.
[0004]
Therefore, it is conceivable to manufacture a slit disk using a thick metal plate having a predetermined rigidity. However, in the case of a thick metal plate, the etching accuracy at the time of forming the slit is reduced. If the slit disk has a small diameter in order to reduce the size of the optical rotary encoder, it is necessary to form the slit with high precision, so it is difficult to manufacture the slit disk using a thick metal plate. It is.
[0005]
In view of the above, an object of the present invention is to propose a method of manufacturing a slit plate of an optical rotary encoder that can form a slit with high accuracy using a metal plate having high strength and rigidity. .
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a method of manufacturing a slit plate of an optical rotary encoder,
A thin film forming step of forming a metal thin film made of a different metal material on both surfaces of a metal substrate for a slit plate,
An etching step of forming a slit by performing an etching process on the metal thin film and the metal base material,
The material of the metal thin film and the metal base is selected so that the etching rate of the metal thin film is lower than the etching rate of the metal base.
[0007]
In the manufacturing method of the present invention, the slit shape is accurately defined by the metal thin film having a low etching rate formed on both surfaces of the metal substrate. Further, by increasing the thickness of the metal substrate, the strength and rigidity of the slit plate can be made sufficient. Therefore, it is possible to manufacture a slit plate in which distortion hardly occurs and resonance hardly occurs during high-speed rotation driving.
[0008]
Here, a copper alloy base material can be used as the metal base material, and a nickel thin film can be used as the metal thin film.
[0009]
In this case, if the thickness of the metal substrate is 50 to 80 microns and the thickness of the metal thin film is 15 to 20 microns, a slit can be formed with a desired accuracy, and a desired strength and rigidity can be obtained. It was confirmed that a slit plate provided with was obtained.
[0010]
Next, the present invention relates to a slit plate of an optical rotary encoder, which is characterized by being manufactured by the method of the present invention. Further, the present invention relates to an optical rotary encoder, which is provided with a slit plate manufactured by the method of the present invention.
[0011]
The slit plate of the present invention has high strength and rigidity, and the slit is formed with high accuracy. Therefore, distortion is less likely to occur in the work of fixing to the rotating shaft, and resonance is less likely to occur during high-speed rotation driving. Therefore, an optical rotary encoder with high detection accuracy can be obtained.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of a method for manufacturing a slit plate of an optical rotary encoder according to the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is an explanatory view showing the manufacturing method of the present embodiment, and the manufacturing method of the present embodiment will be described with reference to this drawing. First, a disk 1 made of a copper alloy having a thickness of 50 to 80 microns is prepared as a metal substrate. As shown in FIG. 1A, a metal thin film having the same thickness is formed on both surfaces 1a and 1b of the disk 1. In this example, nickel thin films 2 and 3 having a thickness of 15 to 20 microns are formed.
[0014]
Next, the slits 4 are formed by etching the copper alloy disc 1 having the nickel thin films 2 and 3 formed on both sides thereof from both sides. Here, since the etching rate of nickel is lower than that of the copper alloy, the openings 2a and 3a for slits are formed in the nickel thin films 2 and 3 with high accuracy. Since the inner copper alloy disc 1 has a high etching rate, as shown in FIGS. 1B and 1C, when the slit openings 2a and 3a are formed in the nickel thin films 2 and 3, the left and right sides are left and right. Etching is progressing to a state in which a slightly larger slit opening 1c is formed. Thus, the slit disk 5 is obtained.
[0015]
Since the slit disk 5 of this example uses the copper alloy disk 1 of 50 to 80 microns as a base material, the slit disk 5 has higher strength and rigidity than a conventional metal slit disk. Therefore, the slit disk 5 is unlikely to be distorted or bent. In addition, resonance hardly occurs in the high-speed rotation driving state. Further, since the shape of the slit 4 is defined by the slit openings 2a, 3a formed by etching the nickel thin films 2, 3, the slit 4 is formed with high accuracy.
[0016]
Therefore, the slit disk 5 of the present embodiment does not suffer from such a problem that distortion occurs when the slit disk 5 is attached to a rotating shaft or the like and abnormalities appear in the detection signal waveform. Further, no abnormality in the detection signal occurs due to resonance during high-speed rotation driving.
[0017]
In addition, since copper alloy has a high etching rate as a metal base material that imparts strength and rigidity to the slit disk 5, the etching time is long and the manufacturing time of the slit disk is not long. . In addition, since strength and rigidity are high, there are advantages such as an improvement in product yield.
[0018]
(Other embodiments)
In the above example, a copper alloy disk is used as the metal substrate, and a nickel thin film is used as the metal thin film. A thin film can also be formed.
[0019]
【The invention's effect】
As described above, in the method for manufacturing a slit plate of an optical rotary encoder of the present invention, a metal thin film having a low etching rate is formed on both surfaces of a metal base made of a metal material having a high etching rate, and the slit is formed by etching. Has formed. Therefore, the metal substrate provides the slit plate with desired strength and rigidity, and the metal thin film allows the slit to be etched with high accuracy.
[0020]
Therefore, according to the present invention, it is possible to manufacture a slit plate in which distortion is less likely to occur, resonance is less likely to occur during high-speed rotation driving, and slits are accurately formed. Further, since the metal base material is sufficiently thick, handling during manufacturing processing is easy, and a slit plate can be manufactured with high yield. Further, since the etching rate of the metal base material is high, the slit plate can be manufactured in the same manufacturing time as the conventional slit plate even if it is thick.
[0021]
Next, since the slit plate manufactured by the method of the present invention has high strength and rigidity and the slits are formed with high precision, it is possible to avoid the occurrence of a detection signal abnormality due to distortion or resonance during high-speed rotation driving. Therefore, an optical rotary encoder that can obtain a highly accurate detection signal can be realized.
[Brief description of the drawings]
FIG. 1 is a view showing a method of manufacturing a slit disk to which the present invention is applied, and FIG. 1 (a) is a partial cross-sectional view showing a state in which nickel thin films are formed on both surfaces of a copper alloy disk; (b) is a cross-sectional view showing a state in which a slit is formed by etching, and (c) is a partial plan view thereof.
[Explanation of symbols]
1 Copper alloy disc (metal substrate)
1a, 1b Disk surface 1c Slit opening 2, 3 Nickel thin film (metal thin film)
2a, 3a Slit opening 4 Slit 5 Slit disk

Claims (5)

A thin film forming step of forming a metal thin film made of a different metal material on both surfaces of a metal substrate for a slit plate,
An etching step of forming a slit by performing an etching process on the metal thin film and the metal base material,
The method for manufacturing a slit plate of an optical rotary encoder, wherein the materials of the metal thin film and the metal base are selected so that the etching rate of the metal thin film is lower than the etching rate of the metal base. . In claim 1,
The metal substrate is made of a copper alloy,
A method for manufacturing a slit plate of an optical rotary encoder, wherein the metal thin film is made of nickel. In claim 2,
The thickness of the metal substrate is 50 to 80 microns,
A method for manufacturing a slit plate of an optical rotary encoder, wherein the thickness of the metal thin film is 15 to 20 microns. A slit plate for an optical rotary encoder manufactured by the manufacturing method according to claim 1. An optical rotary encoder comprising the slit plate according to claim 4.

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