Reflective optical scale for encoders, reflective optical encoder, method for manufacturing a reflective optical scale for encoders, and multi-faceted reflective optical scale for encoders.

Abstract

This invention provides a reflective optical scale for encoders with reduced periphery sagging. [Solution] The present disclosure provides a reflective optical scale 10 for an encoder, comprising a disc-shaped metal substrate 1 having a first surface and a second surface opposite the first surface, and a low-reflectivity layer 2 arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate, wherein the metal substrate has a reflectivity of 50% or more on at least the first surface side, a thickness of 0.05 mm or more and 0.60 mm or less, the metal substrate has a sag on the outer peripheral edge of the first surface side, the width of the sag is 500 μm or less, the metal substrate is a perforated disc shape with a central hole, the difference between the outer and inner diameters of the perforated disc-shaped metal substrate is 8 mm or more and 13 mm or less, and the ratio of the thickness T2 at the outer peripheral edge of the metal substrate to the thickness T1 of the metal substrate (T2 / T1) is 0.70 or more and 0.90 or less.

Description

[Technical Field]

[0001] This disclosure relates to a reflective optical scale for encoders, a reflective optical encoder, a method for manufacturing a reflective optical scale for encoders, and a multi-faceted reflective optical scale for encoders. [Background technology]

[0002] Conventionally, optical encoders have been used in servo motors and other devices equipped with control mechanisms. Optical encoders include through-beam encoders and reflective encoders. Reflective encoders have the advantage of having a shorter optical path than through-beam encoders, making them easier to miniaturize and thin, and also being easier to assemble because they do not require the positioning of light-emitting elements or light-receiving elements.

[0003] A reflective optical encoder includes a reflective optical scale, a light source such as an LED that illuminates the scale, and a photodetector that detects the reflected light from the scale. The reflective optical scale has alternating reflective regions (high-reflection regions) and non-reflective regions (low-reflection regions), and the reflectivity of light in the reflective regions is higher than the reflectivity of light in the non-reflective regions (for example, Patent Document 1). As a result, the intensity of light reflected from the scale and incident on the photodetector varies depending on the change in the scale's position. The photodetector detects the changes in light intensity caused by the scale's movement in the length-measuring direction. The reflective optical encoder can process this displacement information of the scale's position according to the detected changes in light intensity and obtain positional information. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-241248 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Conventionally, reflective optical scales are manufactured by separating a polyhedron, in which multiple reflective optical scales are arranged side by side, into individual pieces. In the piece separation process, etching is often used because it provides good processing accuracy. However, piece separation by etching is disadvantageous in terms of cost.

[0006] Therefore, the inventors of this application attempted to create individual pieces of a multi-faceted reflective optical scale by punching. However, the scales created by punching exhibit burrs at the outer edges (hereinafter also referred to as outer edge burrs). The inventors of this application found that if outer edge burrs occur in the low-reflection region where the low-reflection layer is formed, peeling or cracking of the low-reflection layer may occur. Therefore, they considered not placing the low-reflection layer in the region where outer edge burrs occur due to punching. On the other hand, since optical scales for encoders usually require a low-reflection region of a predetermined size depending on the encoder device, providing a region without a low-reflection layer at the outer edge of the optical scale would increase the actual scale size. Therefore, there is a need for a reflective optical scale for encoders in which the outer edge burr region caused by punching is reduced.

[0007] This invention has been made in view of the above circumstances, and its main objective is to provide a reflective optical scale for encoders in which the outer edge sagging region is reduced. [Means for solving the problem]

[0008] One embodiment of the present disclosure provides a reflective optical scale for an encoder, comprising a disc-shaped metal substrate having a first surface and a second surface facing the first surface, and a low-reflectivity layer arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate, wherein the metal substrate has a reflectivity of 50% or more on at least the first surface side, a thickness of 0.05 mm or more and 0.60 mm or less, and the metal substrate has a sag on the outer peripheral edge of the first surface side, with a width of 500 μm or less.

[0009] Another embodiment of the present disclosure provides a reflective optical encoder comprising the above-described reflective optical scale for encoder, a light source for irradiating the surface of the reflective optical scale for encoder on the side where the low-reflectivity layer is located with measurement light, and a photodetector for detecting reflected light from the reflective optical scale for encoder.

[0010] Another embodiment of the present disclosure provides a method for manufacturing a reflective optical scale for an encoder, comprising the steps of: manufacturing a multi-panel assembly having a metal substrate for processing having a first surface and a second surface facing the first surface, wherein the reflectance of at least the first surface side is 50% or more, and the thickness of the metal substrate is 0.05 mm or more and 0.60 mm or less; and a pattern-shaped low-reflectance layer arranged in a circular manner and multi-paneled on the first surface side of the metal substrate for processing, wherein the outer peripheral punching lines of the reflective optical scale for an encoder are formed outside the outer peripheral surface of each of the low-reflectance layers; and a piece-forming step to obtain a reflective optical scale for an encoder by punching the multi-panel assembly along the outer peripheral punching lines to form individual pieces.

[0011] Another embodiment of the present disclosure provides a poly-mounted reflective optical scale for encoders, comprising a metal substrate for processing having a first surface and a second surface opposite to the first surface, wherein the reflectivity of at least the first surface is 50% or more, and the thickness of the metal substrate is 0.05 mm or more and 0.60 mm or less; and a patterned low-reflectivity layer arranged in a circular manner and mounted on the first surface side of the metal substrate for processing, wherein the outer edge punching lines of the reflective optical scale for encoders are formed outside the outer edge surface of each of the low-reflectivity layers, and the distance between the outer edge punching lines of the reflective optical scale for encoders and the outer edge surface of the low-reflectivity layer is 500 μm or more and 1500 μm or less. [Effects of the Invention]

[0012] This disclosure offers the advantage of providing a reflective optical scale for encoders with reduced periphery sagging.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic top view illustrating a reflective optical scale for an encoder in the present disclosure. [Figure 2] It is a partial enlarged cross-sectional view illustrating a reflective optical scale for an encoder in the present disclosure. [Figure 3] It is a schematic cross-sectional view illustrating a reflective optical scale for an encoder in the present disclosure. [Figure 4] It is a schematic perspective view illustrating a reflective optical encoder in the present disclosure. [Figure 5] It is a schematic top view illustrating a multi-sided attachment body of a reflective optical scale for an encoder in the present disclosure. [Figure 6] It is a schematic cross-sectional view illustrating a punching device used in the singulation process in the manufacturing method of a reflective optical scale for an encoder in the present disclosure. [Figure 7] It is a graph showing the results of Experimental Examples 1-1 to 1-6 and Experimental Examples 2-1 to 2-5.

Modes for Carrying Out the Invention

[0014] The present disclosure includes, in embodiments, a reflective optical scale for an encoder, a reflective optical encoder, a manufacturing method of a reflective optical scale for an encoder, and a multi-sided attachment body of a reflective optical scale for an encoder. Hereinafter, embodiments of the present disclosure will be described with reference to the drawings and the like. However, the present disclosure can be implemented in many different modes and is not to be construed as being limited to the description of the embodiments exemplified below. Also, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form for clearer explanation, but this is merely an example and does not limit the interpretation of the present disclosure. Further, in this specification and each figure, elements similar to those described above with respect to the previously presented figures may be denoted by the same reference numerals, and detailed description may be omitted as appropriate.

[0015] In this specification, when describing a configuration in which one member is placed on top of another member, unless otherwise specified, the terms "on top" or "below" include both cases: one in which the other member is placed directly above or below the other member so as to be in contact with it, and another in which the other member is placed above or below the other member via yet another member. Similarly, when describing a configuration in this specification in which one member is placed on the surface of another member, unless otherwise specified, the terms "on the surface" or "on the surface" include both cases: one in which the other member is placed directly above or below the other member so as to be in contact with it, and another in which the other member is placed above or below the other member via yet another member.

[0016] Furthermore, in this specification, "reflective optical scale for encoders" may sometimes be simply referred to as "optical scale."

[0017] The following describes in detail the reflective optical scale for encoders, the reflective optical encoder, the method for manufacturing the reflective optical scale for encoders, and the multi-faceted reflective optical scale for encoders as described in this disclosure.

[0018] A. Reflective optical scale for encoders Figure 1 is a schematic top view showing an example of a reflective optical scale for an encoder in this disclosure. Figure 2(a) is an enlarged cross-sectional view of portion a of the dotted line frame a in Figure 1, AA. Figure 2(b) is an enlarged cross-sectional view of portion b of the dotted line frame b in Figure 1, BB.

[0019] The reflective optical scale 10 for encoders shown in Figures 1 and 2 comprises a disc-shaped metal substrate 1 having a first surface 1a and a second surface 1b opposite the first surface, and a low-reflection layer 2 arranged in a pattern along the circumferential direction of the metal substrate 1 on the first surface 1a side of the metal substrate 1. In this disclosure, the metal substrate 1 has a reflectance of at least the first surface 1a of which is greater than or equal to a predetermined value, and the thickness of the metal substrate 1 itself is within a predetermined range. Furthermore, as shown in Figure 2(b), the metal substrate 1 has a sag P on the outer peripheral edge on the first surface 1a side, and the width X of the sag P is less than or equal to a predetermined value. The reflective optical scale 10 for encoders in Figure 1 has a perforated disc shape, and low-reflection regions R2, which are regions where the low-reflection layer 2 is provided, and high-reflection regions R1, which are regions where the low-reflection layer 2 is not provided, are alternately arranged in the circumferential direction. The low-reflection region R2 has the metal substrate 1 and the low-reflection layer 2 in the thickness direction of the reflective optical scale 10 for encoders. The high-reflectivity region R1 has a metal substrate 1. The reflectance of light in the high-reflectivity region R1 is higher than the reflectance of light in the low-reflectivity region R2. Note that the reflectance of light in the high-reflectivity region R1 and the reflectance of light in the low-reflectivity region R2 represent the reflectance at the same wavelength and the same angle of incidence.

[0020] The reflective optical scale for encoders in this disclosure has a burr on the outer edge of the first surface of the metal substrate, and the width of the burr is less than or equal to a predetermined value. Optical scales with such a burr on the outer edge of the metal substrate are usually manufactured by punching. Therefore, they are more cost-effective than optical scales manufactured by etching. Furthermore, optical scales with a reduced outer edge burr on the metal substrate can narrow the width of the area where the low-reflection layer is not formed, thereby suppressing peeling and cracking of the low-reflection layer while suppressing an increase in the size of the scale. The reflective optical scale for encoders in this disclosure will be described in detail below.

[0021] 1.Metal base material (1) Outer edge sagging The metal substrate in this disclosure is disc-shaped and has a first surface and a second surface opposite to the first surface, and has a sag on the outer edge of the first surface. Furthermore, the width of the sag of the metal substrate in this disclosure is 500 μm or less, preferably 450 μm or less, more preferably 400 μm or less, and particularly preferably 350 μm or less. If the width of the sag is too large, it may overlap with the low-reflection layer formation area, which may cause peeling or cracking of the low-reflection layer. On the other hand, the width of the sag of the metal substrate in this disclosure is, for example, 10 μm or more, may be 100 μm or more, may be 200 μm or more, or may be 250 μm or more. If the width of the sag is too small, there is a risk of undulation in the scale. Specifically, the width of the sag of the metal substrate in this disclosure is, for example, 10 μm or more and 500 μm or less, preferably 100 μm or more and 450 μm or less, more preferably 200 μm or more and 400 μm or less, and particularly preferably 250 μm or more and 350 μm or less.

[0022] In this specification, the width of the sag refers to the distance X between the point where the first surface 1a of the metal substrate 1 begins to sag and the extension of the outer peripheral surface 1c of the metal substrate 1, as shown in Figure 2(b). The method for measuring the width of the burr, i.e., the distance X, is as follows: First, the metal substrate is cut perpendicular to the first surface using methods such as metal shears, shearing, or laser cutting, and the cut surface is polished to a flat surface using a polishing machine to obtain a measurement sample. The cut surface of the measurement sample is observed with a microscope from a direction perpendicular to the cut surface, and the distance X is measured between the point where the first surface 1a of the metal substrate 1 begins to burr and the extension of the outer peripheral surface 1c of the metal substrate 1. The point where the first surface 1a of the metal substrate 1 begins to burr is defined as the point where it is no longer parallel to the flat portion of the first surface of the metal substrate 1, specifically a point that is 3 μm or more away in the vertical direction. Furthermore, the width of the outer peripheral burr is the average value obtained by observing and measuring at a total of 12 points, with the circumference of the scale marked in 30° increments.

[0023] The amount of sagging of the metal substrate in this disclosure is, for example, 500 μm or less, preferably 450 μm or less, more preferably 400 μm or less, and particularly preferably 350 μm or less. If the amount of sagging is too large, there is a risk of damage due to insufficient scale strength. On the other hand, the amount of sagging of the metal substrate in this disclosure is, for example, 10 μm or more, preferably 200 μm or more, more preferably 250 μm or more, and particularly preferably 300 μm or more. If the amount of sagging is too small, there is a risk of undulation in the scale. Specifically, the amount of sagging of the metal substrate in this disclosure is, for example, 10 μm or more and 500 μm or less, preferably 200 μm or more and 450 μm or less, more preferably 250 μm or more and 400 μm or less, and particularly preferably 300 μm or more and 350 μm or less.

[0024] In this specification, the amount of sag refers to the distance Y between the upper end of the outer surface 1c of the metal substrate 1 (the boundary point between the sag and the outer surface 1c) and the extension line of the first surface 1a of the metal substrate, as shown in Figure 2(b). The method for measuring the amount of sagging, i.e., the distance Y, is to prepare a measurement sample in the same manner as the method for measuring the width of the sagging described above, and then measure the distance Y. The upper end of the outer surface 1c of the metal substrate 1 (the boundary point between the sagging and the outer surface 1c) is defined as the point where the outer surface 1c of the metal substrate 1 is no longer parallel to the outer surface 1c, specifically, a point that is 3 μm or more away in the planar direction.

[0025] Furthermore, the ratio of the thickness T2 at the outer edge of the metal substrate to the thickness T1 of the metal substrate (T2 / T1), as described later, is, for example, 0.70 or more, and may be 0.80 or more. If T2 / T1 is too small, there is a risk of damage due to insufficient strength of the scale. On the other hand, the above ratio is, for example, 0.90 or less, and may be 0.87 or less. If T2 / T1 is too large, there is a risk of undulation occurring in the scale. Specifically, the ratio of the thickness T2 at the outer edge of the metal substrate to the thickness T1 of the metal substrate in this disclosure (T2 / T1) is preferably 0.70 or more and 0.90 or less, and more preferably 0.80 or more and 0.87 or less.

[0026] If the metal substrate in this disclosure is in the shape of a perforated disc, it may have a burr (hereinafter also referred to as an inner circumferential burr) on the inner circumferential edge of the first surface. The width and amount of the inner circumferential burr may be the same as or different from the width and amount of the outer circumferential burr.

[0027] (2)Reflectance The metal substrate in this disclosure has a reflectance of at least 50% on its first surface, which may be 55% or more, or 60% or more. The reflectance is, for example, 100% or less. Specifically, the reflectance of the first surface of the metal substrate in this disclosure is, for example, 50% or more and 100% or less, preferably 55% or more and 100% or less, and more preferably 60% or more and 100% or less.

[0028] The reflectance referred to here is, for example, the reflectance to detection light used in an optical encoder. When the incident light has a wavelength within the range of 500 nm to 1000 nm, it is more preferable that the reflectance be within the above range when the incident angle is in the range of 5° to 70°. For measuring the reflectance, a Shimadzu Corporation SolidSpec 3700DUV can be used, with an irradiation beam size of approximately 6 mm x 15 mm. Both P-polarized and S-polarized light are measured, and the average of the sum is taken to calculate the 45° linear polarization and then calculate the reflectance. If the reflectance of the metal substrate is within the above range, the difference between the reflectance in the high-reflectance region and the low-reflectance region is large, which prevents false detection by the photodetector and improves the accuracy of signal detection.

[0029] (3) Thickness In this disclosure, the metal substrate has a thickness T1 of 0.05 mm or more, preferably 0.1 mm or more, and more preferably 0.3 mm or more. If the thickness of the metal substrate is within the above range, the strength as a reflective optical scale for an encoder will be sufficient. On the other hand, the thickness T1 of the metal substrate is 0.60 mm or less, preferably 0.50 mm or less, and more preferably 0.4 mm or less. If the thickness of the metal substrate is within the above range, it will be easy to set the width of the outer periphery sag within the above range. Note that the thickness T1 of the metal substrate refers to the average thickness of the metal substrate excluding the sag region. Specifically, the thickness T1 of the metal substrate in this disclosure is 0.05 mm or more and 0.60 mm or less, preferably 0.10 mm or more and 0.50 mm or less, and more preferably 0.30 mm or more and 0.40 mm or less.

[0030] (4) Others Examples of metal substrate materials that have the above reflectivity and yield the above outer edge sag width include stainless steel (SUS), copper, and aluminum.

[0031] Furthermore, the metal substrate in this disclosure is disc-shaped, and may be, for example, a perforated disc with a central hole, or it may not have a central hole. When the metal substrate is a perforated disc, in plan view, the outer diameter may be, for example, 15 mm or more and 20 mm or more. On the other hand, the outer diameter may be, for example, 70 mm or less and 60 mm or less. Specifically, the outer diameter may be, for example, 15 mm or more and 70 mm or less, or 20 mm or more and 60 mm or less. Also, the inner diameter may be, for example, 5 mm or more and 20 mm or less. Also, the difference between the outer diameter and the inner diameter (outer-to-inner diameter difference) may be, for example, 8 mm or more and 13 mm or less. Within this range, the undulation of scale that occurs during punching can be suppressed.

[0032] 2.Low reflective layer In this disclosure, the low-reflectance layer is provided on the first surface side of a metal substrate in a pattern along the circumferential direction of the metal substrate. In this disclosure, the low-reflectance region, which is the area where the low-reflectance layer is provided, has a reflectance at any wavelength within the wavelength range of 500 nm to 1000 nm that is, for example, 10% or less, may be 5% or less, or may be 1% or less. On the other hand, the reflectance of the low-reflectance region is, for example, 0% or more and 10% or less, preferably 0% or more and 5% or less, and more preferably 0% or more and 1% or less.

[0033] In the reflective optical scale for encoders of this disclosure, it is preferable that the low-reflection layer is not present in the region from the outer periphery of the metal substrate up to 500 μm inward. The metal substrate in the reflective optical scale for encoders of this disclosure has a sag at the outer periphery, with a width of 500 μm or less. By not having a low-reflection layer in the region from the outer periphery of the metal substrate up to 500 μm inward, peeling and cracking of the low-reflection layer can be suppressed.

[0034] Specifically, as shown in Figure 2(b), the distance D1 between the outer surface 1c of the metal substrate 1 and the outer surface 2c of the low-reflection layer 2 is preferably 500 μm or more, more preferably 550 μm or more, and particularly preferably 600 μm or more. If the distance D1 is within the above range, peeling and cracking of the low-reflection layer can be easily suppressed. On the other hand, the distance D1 is, for example, 1500 μm or less, preferably 1000 μm or less, and more preferably 900 μm or less. If the distance D1 is within the above range, the enlargement of the size of the reflective optical scale for the encoder can be suppressed. Specifically, the above distance D1 is, for example, 500 μm or more and 1500 μm or less, preferably 550 μm or more and 1000 μm or less, and more preferably 600 μm or more and 900 μm or less.

[0035] Furthermore, the value of distance D1 described above is also applicable to a reflective optical scale for an encoder, which has a disc-shaped metal substrate having a first surface and a second surface facing the first surface, and a low-reflection layer arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate.

[0036] The low-reflection layer in this disclosure is provided on the first surface side of a metal substrate in a pattern along the circumferential direction of the metal substrate. The configuration of the low-reflection layer is not particularly limited, as long as the reflectance of light incident on the low-reflection region (the area where the low-reflection layer is provided) is smaller than the reflectance of light incident on the high-reflection region.

[0037] In this disclosure, it is preferable to have a three-layer structure consisting of a metallic chromium film and chromium oxide and chromium nitride films formed in any order on the metallic chromium film, starting from the metal substrate side. With such a low-reflectance layer, the reflectance of light incident on the low-reflectance region can be reduced to 10% or less, preferably 5% or less, and even further to 1% or less, at any wavelength within the wavelength range of 500 nm to 1000 nm. On the other hand, the reflectance of the low-reflectance region is, for example, 0% or more. Specifically, the reflectance of the low-reflectance region in this disclosure is, for example, 0% or more and 10% or less, preferably 0% or more and 5% or less, and more preferably 0% or more and 1% or less.

[0038] Furthermore, it is preferable that the reflectance in the low-reflectance region satisfies the above range at any angle within the incident angle range of 5° to 70°. This allows for a large difference between the reflectance in the high-reflectance region and the reflectance in the low-reflectance region. In addition, by preparing only metallic chromium, chromium oxide films and chromium nitride films can be easily formed using reactive sputtering or the like. Moreover, high-resolution patterning can be performed more easily compared to silicon oxide films.

[0039] In this specification, "chromium oxide film and chromium nitride film formed in any order on a metallic chromium film" means that the films may be formed in the order of metallic chromium film, chromium oxide film, and chromium nitride film, or in the order of metallic chromium film, chromium nitride film, and chromium oxide film.

[0040] For example, the low-reflection layer 2 of the reflective optical scale 10 for encoder shown in Figure 3(a) has, from the metal substrate 1 side, a metallic chromium film 2c, a chromium nitride film 2b formed on the metallic chromium film 2c, and a chromium oxide film 2a formed on the chromium nitride film 2b. On the other hand, the low-reflection layer 2 of the reflective optical scale 10 for encoder shown in Figure 3(b) has, from the metal substrate 1 side, a metallic chromium film 2c, a chromium oxide film 2a formed on the metallic chromium film 2c, and a chromium nitride film 2b formed on the chromium oxide film 2a.

[0041] The outermost surface of the low-reflection region is preferably the surface of the chromium oxide or chromium nitride film of the low-reflection layer, and is particularly preferably the surface of the chromium oxide film. This is because it can more effectively reduce the reflectance in the low-reflection region.

[0042] Hereinafter, the low-reflection layer with metallic chromium film, chromium nitride film, and chromium oxide film arranged in this order will be referred to as the first specification low-reflection layer, and the low-reflection layer with metallic chromium film, chromium oxide film, and chromium nitride film arranged in this order will be referred to as the second specification low-reflection layer.

[0043] (1) Low-reflection layer of the first specification In this specification, the low-reflectance layer consists of a metallic chromium film, a chromium nitride film, and a chromium oxide film arranged in that order from the substrate side. The low-reflectance region having this specification can reduce the reflectance at any wavelength within the wavelength range of 500 nm to 1000 nm of light irradiated from a light source to 5% or less, and especially to 0.5% or less. Furthermore, the change in reflectance with respect to wavelength changes is gradual, making it easy to control the reflectance. Specifically, the above reflectance can be reduced to 0% or more and 5% or less, and especially to 0% or more and 0.5% or less. Each layer will be described in detail below.

[0044] (a) metallic chromium film In this specification, the metallic chromium film is provided on a metal substrate. The metallic chromium film is a layer made of metallic chromium. The metallic chromium film is a layer that substantially does not transmit light irradiated from a light source, and it is preferable that the transmittance is 0.0% or more and 1.0% or less. The transmittance can be measured using a spectrophotometer (MPC-3100) manufactured by Shimadzu Corporation or the like. The film thickness is, for example, 40 nm or more, preferably 70 nm or more.

[0045] Here, the "thickness" of each component refers to the thickness obtained by a general measurement method. Examples of thickness measurement methods include the stylus method, which calculates the thickness by tracing the surface with a stylus and detecting irregularities, and the optical method, which calculates the thickness based on the spectral reflectance spectrum. Specifically, the thickness can be measured using the P-15 stylus-type film thickness gauge manufactured by KLA-Tencor Co., Ltd. Note that the average value of the thickness measurement results at multiple locations on the component in question may also be used as the thickness.

[0046] For forming metallic chromium films, physical vapor deposition (PVD) methods such as sputtering, ion plating, and vacuum deposition are used.

[0047] (b) Chromium nitride film In this specification, the chromium nitride film is positioned between the metallic chromium film and the chromium oxide film. Unlike chromium oxidizite and chromium carbide oxidizite, the chromium nitride film's main components are chromium and nitrogen, and it substantially contains no impurities other than chromium and nitrogen.

[0048] The value of x, which represents the atomic ratio of Cr to N in a chromium nitride (CrNx) film, is preferably between 0.4 and 1.1.

[0049] Furthermore, the chromium nitride film has a purity of 80% to 100% of chromium and nitrogen, with the entire film being considered as 100 atomic percent, and preferably within the range of 90% to 100%. Impurities such as hydrogen, oxygen, and carbon may be present.

[0050] Thickness of chromium nitride film (T N The thickness of the chromium oxide film (T) is preferably in the range of 5 nm to 100 nm, and particularly preferably in the range of 10 nm to 80 nm. O In relation to ), when the wavelength is 850 nm, T N and T O If the sum of these is 40 nm or more, and the wavelength is 550 nm, then T N and T OIt is preferably 20 nm or more in total with [the relevant part]. With such a film thickness range, compared to the case outside the above range, the reflectance in the low-reflection region can be easily reduced to 10% or less, particularly 5% or less. Furthermore, the film thickness (T N ) of the chromium nitride film is preferably within the range of 10 nm or more and 80 nm or less because it becomes easy to reduce the reflectance over the entire region from green to infrared (about 500 nm or more and 1000 nm or less).

[0051] As a method for forming chromium nitride, for example, physical vapor deposition (PVD) methods such as reactive sputtering method, ion plating method, and vacuum evaporation method are used. When using the reactive sputtering method, nitrogen is introduced into argon (Ar) gas, and a chromium nitride film can be formed by the reactive sputtering method using a Cr target. At this time, the composition of the chromium nitride film can be controlled by controlling the ratio of Ar gas and nitrogen gas.

[0052] (c) Chromium oxide film The chromium oxide film is formed on the chromium nitride film, and its main components are chromium and oxygen. Unlike chromium oxynitride, chromium oxycarbide nitride, etc., it does not substantially contain impurities other than chromium and oxygen.

[0053] As y representing the atomic ratio of Cr and O in the chromium oxide (CrOy) film, it is preferably 1.4 or more and 2.1 or less.

[0054] Specifically, for the chromium oxide film, taking the whole film as 100 atomic%, the purity of the ratio of chromium and oxygen within the range of 80 - 100%, particularly within the range of 90% or more and 100% or less, is preferable. As impurities, hydrogen, nitrogen, carbon, etc. may be contained.

[0055] The film thickness of the chromium oxide film is not particularly limited, but it is preferably within the range of 5 nm or more and 100 nm or less, particularly within the range of 10 nm or more and 80 nm or less. Also, the film thickness (T O ) of chromium oxide is [related to] the film thickness (T NIt is preferable that the total film thickness of the chromium oxide film (T) is within the range described in "(1) Low-reflection layer of the first specification (b) chromium nitride film" above. Furthermore, the film thickness of the chromium oxide film (T O ) is preferable in the range of 10 nm to 65 nm because it makes it easier to reduce reflectance across the entire green to infrared region (approximately 500 to 1000 nm).

[0056] Physical vapor deposition (PVD) methods such as reactive sputtering, ion plating, and vacuum deposition are used to form chromium oxide. In reactive sputtering, oxygen is introduced into argon (Ar) gas, and a chromium oxide film can be deposited using a Cr target. The composition of the chromium oxide film can be controlled by adjusting the ratio of Ar gas to oxygen gas.

[0057] (2) Low-reflection layer of the second specification In this specification, the low-reflection layer consists of a metallic chromium film, a chromium oxide film, and a chromium nitride film arranged in that order from the metal substrate side. The low-reflection region having this specification can reduce the reflectance of light irradiated from a light source to 5% or less, and especially to 1% or less, at any wavelength within the wavelength range of 500 nm to 1000 nm. Specifically, the above reflectance can be reduced to 0% or more and 5% or less, and especially to 0% or more and 1% or less. Each layer will be described in detail below.

[0058] (a) metallic chromium film In this specification, the metallic chromium film is formed on the substrate. The details of the metallic chromium film are the same as those described above in "(1) Low-reflection layer (a) metallic chromium film of the first specification," so the explanation is omitted here.

[0059] (b) Chromium oxide film In this specification, the chromium oxide film is positioned between the metallic chromium film and the chromium nitride film. The film thickness is not particularly limited, but is preferably in the range of 5 nm to 60 nm, and more preferably in the range of 10 nm to 50 nm. Furthermore, it is preferable to satisfy the relationship with the film thickness of the chromium nitride film described later. This is because it is possible to more reliably reduce the reflectance at any wavelength within the low-reflection wavelength range of 500 nm to 1000 nm to 10% or less, and more preferably to 5% or less.

[0060] Furthermore, the thickness of the chromium oxide film (T O ) is preferable in the range of 5 nm to 35 nm because it makes it easier to reduce reflectance across the entire green to infrared (approximately 500 to 1000 nm) region.

[0061] Details regarding the physical properties, composition, and formation method of the chromium oxide film are the same as those described above in "(1) Low-reflection layer of the first specification (c) chromium oxide film," and therefore will not be explained here.

[0062] (c) Chromium nitride film The chromium nitride film in this specification is formed on a chromium oxide film. The thickness of the chromium nitride film in this specification is not particularly limited, but for example, it is preferably in the range of 5 nm to 100 nm, and particularly preferably in the range of 10 nm to 80 nm. Furthermore, the thickness of the chromium oxide film (T O In relation to ), when the wavelength is 850 nm, T N and T O If the sum of these is 30 nm or more, and the wavelength is 550 nm, then T N and T O It is preferable that the sum of these is 15 nm or more. Furthermore, the thickness of the chromium nitride film in this specification (T N ) is preferable in the range of 10 nm to 60 nm, as it makes it easier to reduce reflectance across the entire region from green to infrared (approximately 500 nm to 1000 nm).

[0063] The method for forming the low-reflectance layer in this disclosure is not particularly limited, but it can be manufactured by selective etching or lift-off. Specifically, a metallic chromium film is formed on a metal substrate, for example by sputtering, and then a chromium nitride film and a chromium oxide film are formed. Next, the metallic chromium film, chromium nitride film and chromium oxide film can be patterned by photolithography and etching to manufacture a patterned low-reflectance layer.

[0064] Alternatively, the films can be formed by creating a resist pattern on a metal substrate and then using a known vacuum deposition method such as sputtering to create metallic chromium films, chromium nitride films, and chromium oxide films. Subsequently, the resist pattern is removed to lift off the metallic chromium films, chromium nitride films, and chromium oxide films formed directly above the resist pattern, thereby obtaining patterns of chromium nitride films and chromium oxide films.

[0065] In this disclosure, the low-reflectance region is defined as having a reflectance of, for example, 10% or less at any wavelength within the wavelength range of 500 nm or more and 1000 nm or less, and may also be 5% or less, or 1% or less. Specifically, the reflectance of the low-reflection region in this disclosure is, for example, 0% or more and 10% or less, preferably 0% or more and 5% or less, and more preferably 0% or more and 1% or less. It is preferable that the reflectance of the low-reflection region satisfies the above range at any angle within the incident angle range of 5° to 70°. The outermost surface of the low-reflection region is preferably the surface of the chromium oxide film or chromium nitride film of the low-reflection layer, and particularly preferably the surface of the chromium oxide film. This is because it allows for a more effective reduction of the reflectance in the low-reflection region.

[0066] 3. Other layer configurations The reflective optical scale for encoders in this disclosure may have other layers besides the metal substrate and the low-reflection layer. For example, the reflective optical scale for encoders in this disclosure may have a protective layer between the metal substrate and the low-reflection layer.

[0067] The protective layer is preferably transparent and has the function of protecting the metal substrate. By providing a protective layer, there is no risk of the surface of the metal substrate becoming rough and the surface roughness increasing during etching when forming the low-reflection layer in a pattern. Therefore, diffuse reflection of light can be suppressed. The protective layer may be provided over the entire surface of the metal substrate or in a part of it when viewed from above.

[0068] The material for the protective layer is not particularly limited as long as it is transparent and capable of protecting the highly reflective layer, and may be either an organic or inorganic material.

[0069] The organic material preferably contains a resin. The resin used for the protective layer is not particularly limited as long as it can produce a transparent protective layer. Examples include ionizing radiation-curable resins that harden upon irradiation with ionizing radiation such as ultraviolet rays or electron beams, and thermosetting resins that harden upon heating. Specifically, novolac resins, polyolefin resins, polyester resins, urethane resins, polyimide resins, acrylic resins, and epoxy resins are preferred. Among novolac resins, phenol novolac resins are particularly preferred because they have excellent electrical properties and can suppress problems caused by static charge. Among acrylic resins, trifunctional or higher acrylates such as pentaerythritol tetraacrylate and dipentaerythritol tetraacrylate are particularly preferred because they can enhance photocurability. Among epoxy resins, epoxy acrylate resins having a fluorene structure are preferred because they improve heat resistance, adhesion, and chemical resistance. Cardo epoxy resins are also preferred among epoxy resins because they can provide excellent transparency, heat resistance, surface hardness, and flatness. The organic material may contain not only the resin but also polymerization initiators, various additives, and so on.

[0070] Examples of inorganic materials include inorganic compounds. Examples of inorganic compounds include oxides, oxidized nitrides, nitrides, oxide carbides, and oxide carbidine nitrides of metallic or nonmetallic elements such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, titanium, boron, yttrium, zirconium, cerium, and zinc. Silicon dioxide (SiO2) is particularly preferred. Inorganic compounds may be used alone or as a mixture of the above materials in any proportion.

[0071] 4. Reflective optical scale for encoders The reflective optical scale for encoders of this disclosure is typically used as an optical scale for rotary encoders. The reflective optical scale for encoders is disc-shaped, and may be, for example, a perforated disc with a central hole, or it may not have a central hole. When the reflective optical scale for encoders of this disclosure is a perforated disc, in a plan view, the outer diameter may be, for example, 15 mm or more and 20 mm or more. On the other hand, the outer diameter may be, for example, 70 mm or less and 60 mm or less. Specifically, the outer diameter may be, for example, 15 mm or more and 70 mm or less, or 20 mm or more and 60 mm or less. The inner diameter is, for example, 5 mm or more and 20 mm or less. The difference between the outer diameter and the inner diameter (outer-to-inner diameter difference) is, for example, 8 mm or more and 13 mm or less. Within this range, the waviness of the scale that occurs during punching can be suppressed.

[0072] Furthermore, the reflective optical scale for encoders described herein can be manufactured by the method described later in "C. Method for manufacturing a reflective optical scale for encoders".

[0073] B. Reflective optical encoder This disclosure provides a reflective optical encoder characterized by comprising the above-described reflective optical scale for encoders, a light source that irradiates the surface of the reflective optical scale for encoders on the side where the low-reflectivity layer is arranged with measurement light, and a photodetector that detects reflected light from the reflective optical scale for encoders.

[0074] Figure 4 is a schematic perspective view showing an example of a reflective optical encoder equipped with a reflective optical scale for encoders in this disclosure. The reflective optical encoder 100 in this disclosure includes a reflective optical scale 10 for encoders, and further includes a light source 21 and a photodetector 22. In Figure 4, a fixed slit 23 is positioned between the photodetector 22 and the reflective optical scale 10 for encoders. Because the encoder in this disclosure has a reflective optical scale for encoders with reduced outer periphery sagging as described above, it is cost-effective for the reasons described above, and also has good encoder characteristics because peeling and cracking of the low-reflection layer can be suppressed.

[0075] 1. Reflective optical scale for encoders The reflective optical scale for encoders is the same as the one described in "A. Reflective Optical Scale for Encoders" above, so its explanation is omitted here.

[0076] 2.Light source Examples of light sources include LEDs (light-emitting diodes) and lasers. The wavelength λ of the light emitted from the light source is, for example, in the green to infrared region (approximately 500 nm to 1000 nm). The angle of incidence of the light relative to the optical scale 10 is, for example, between 5° and 70°.

[0077] 3. Photodetector A photodetector detects light reflected on an optical scale. A photodetector includes, for example, a photoreceiving element (e.g., a photoelectric conversion element) such as a photodiode or image sensor.

[0078] 4. Others The reflective optical encoder in this disclosure may include a fixed slit between the photodetector and the reflective optical scale for the encoder. By providing a fixed slit, the change in the amount of light received by the photodetector becomes larger, and the detection sensitivity can be improved. The fixed slit may be provided between the light source and the reflective optical scale for the encoder.

[0079] C. Method for manufacturing a reflective optical scale for an encoder This disclosure provides a method for manufacturing a reflective optical scale for an encoder, comprising the steps of: manufacturing a multi-panel assembly having a metal substrate for processing having a first surface and a second surface facing the first surface, the reflectivity of at least the first surface being 50% or more, and a thickness of 0.05 mm or more and 0.60 mm or less; and a pattern-shaped low-reflectivity layer arranged in a circular manner and multi-paneled on the first surface side of the metal substrate for processing, wherein the outer peripheral punching lines for the reflective optical scale for an encoder are formed outside the outer peripheral surface of each of the low-reflectivity layers; and a piece-forming step to obtain a reflective optical scale for an encoder by punching the multi-panel assembly along the outer peripheral punching lines to form individual pieces.

[0080] Figure 5 is a schematic top view of the poly-faced body 50 produced in the above-described poly-faced body manufacturing process. The poly-faced body 50 in this disclosure comprises a workpiece metal substrate 51 having a reflectivity of at least one first surface of a predetermined value and a thickness within a predetermined range, and a circumferentially arranged pattern of low-reflectivity layers 2 that are poly-faced on the first surface side of the workpiece metal substrate 51. In the poly-faced body 50 in this disclosure, outer peripheral punching lines L for the encoder reflective optical scale are formed on the outside of each low-reflectivity layer 2. By punching along the outer peripheral punching lines L in the individualization process, a reflective optical scale for the encoder is obtained.

[0081] 1. Process for fabricating a multi-faceted body In this process, a multi-panel assembly is produced, comprising a metal substrate to be processed having a reflectivity of at least 50% on its first surface and a thickness of 0.05 mm to 0.60 mm, and a patterned low-reflectivity layer arranged circumferentially and attached in multiple panels to the first surface side of the metal substrate, wherein the outer edge punching lines for a reflective optical scale for an encoder are formed outside the outer surface of each low-reflectivity layer.

[0082] The reflectance and thickness of the first surface of the metal substrate to be processed are the same as those of the first surface of the metal substrate described above. The size of the metal substrate to be processed in plan view is not particularly limited, as long as it is large enough to accommodate multiple patterned low-reflectance layers.

[0083] The low-reflection layer is the same as the low-reflection layer described in "A. Reflective Optical Scale for Encoders" above. Furthermore, the method for applying multiple patterned low-reflection layers to the first surface of the metal substrate to be processed is the same as the method for forming the low-reflection layer described in "A. Reflective Optical Scale for Encoders" above.

[0084] As shown in Figure 5, in the polyhedron in this disclosure, the outer edge punching line L of the encoder reflective optical scale is formed outside the outer edge surface of each low-reflection layer 2. The distance D2 between the outer edge punching line L of the encoder reflective optical scale and the outer edge surface of the low-reflection layer 2 is preferably 500 μm or more, more preferably 550 μm or more, and particularly preferably 600 μm or more. If the above distance D2 is within the above range, outer edge sagging is less likely to occur in the area where the low-reflection layer is formed during punching, thus suppressing peeling and cracking of the low-reflection layer. On the other hand, the distance D2 is, for example, 1500 μm or less, preferably 1000 μm or less, and more preferably 900 μm or less. If the above distance D2 is within the above range, it is possible to suppress the expansion of the size of the encoder reflective optical scale. Specifically, the distance D2 is, for example, 500 μm or more and 1500 μm or less, preferably 550 μm or more and 1000 μm or less, and more preferably 600 μm or more and 900 μm or less.

[0085] Furthermore, a multi-faceted assembly for manufacturing a perforated disc-shaped reflective optical scale for an encoder may have an inner circumference punching line formed for punching out the central hole of the reflective optical scale for the encoder.

[0086] 2.Singulation process In this process, the multi-faceted body produced in the above-mentioned multi-faceted body production process is punched out along the outer peripheral punching line to form individual pieces, thereby obtaining a reflective optical scale for an encoder.

[0087] Figure 6 is a schematic diagram showing an example of a punching apparatus used in the individualization process in the manufacturing method of a reflective optical scale for encoders according to this disclosure. As shown in Figures 6(a) and 6(b), a multi-paneled multi-paneled body 50 is placed on a lower stage 62 having a lower blade 61, and the lower stage 62 is moved upward and the upper stage 63 having an upper blade 64 is moved downward and pressed, thereby punching out the multi-paneled body 50 and obtaining individual reflective optical scales 10 for encoders. At this time, the position of the upper blade is aligned with the outer circumference punching line and the inner circumference punching line. It is also preferable to place a metal substrate pressing member 65 at a position opposite the upper blade 64. The pressing member 65, together with the upper blade 64, clamps the metal substrate during punching, enabling punching with less burr and sagging.

[0088] In this disclosure, by setting the clearance width in this process to, for example, 0.020 mm or less, preferably 0.017 mm or less, and more preferably 0.015 mm or less, it becomes easy to set the width of the outer periphery sag of the reflective optical scale for the encoder within the above range. On the other hand, the clearance width is, for example, 0.003 mm or more, preferably 0.004 mm or more, and more preferably 0.006 mm or more. By setting the clearance width within the above range, the load on the blades of the punching device can be reduced. The clearance width refers to the distance C in the width direction between the end face of the upper blade 64 and the end face of the lower blade 61, as shown in Figure 6(b). Specifically, the clearance width is, for example, 0.003 mm or more and 0.020 mm or less, preferably 0.004 mm or more and 0.017 mm or less, and more preferably 0.006 mm or more and 0.015 mm or less.

[0089] The reflective optical scale for encoders obtained in this process is the same as the reflective optical scale for encoders described in "A. Reflective Optical Scale for Encoders" above.

[0090] D. Reflective optical scale with multiple facets for encoders This disclosure provides a multi-panel assembly for an encoder reflective optical scale, comprising a metal substrate for workpiece having a first surface and a second surface facing the first surface, wherein the reflectivity of at least the first surface is 50% or more and the thickness is 0.05 mm or more and 0.60 mm or less; and a patterned low-reflectivity layer arranged in a circular manner and mounted on the first surface side of the metal substrate for workpiece, wherein the outer edge punching lines of the encoder reflective optical scale are formed outside the outer edge surface of each of the low-reflectivity layers, and the distance between the outer edge punching lines of the encoder reflective optical scale and the outer edge surface of the low-reflectivity layer is 500 μm or more and 1500 μm or less.

[0091] According to the multi-faceted reflective optical scale for encoders of this disclosure, the distance between the planned punching line on the outer circumference of the reflective optical scale for encoders and the outer surface of the low-reflection layer is within a predetermined range. This makes it less likely for the outer circumference sagging that occurs during punching to extend to the area where the low-reflection layer is formed, thereby suppressing peeling and cracking of the low-reflection layer. Furthermore, it is possible to suppress the expansion of the size of the reflective optical scale for encoders.

[0092] The multi-faceted reflective optical scale for encoders described herein is the same as that described in "C. Method for Manufacturing a Reflective Optical Scale for Encoders" above, so a further explanation is omitted here.

[0093] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Examples]

[0094] The following experimental examples will further illustrate this disclosure.

[0095] (Experimental Example 1-1) A SUS (stainless steel) substrate with a thickness of 0.3 mm was prepared for processing. Using the punching apparatus shown in Figure 6, the SUS substrate was punched to obtain a perforated disc-shaped SUS substrate with an outer diameter of 23.5 mm and an inner diameter of 15.0 mm. The clearance width C was set to 0.004 mm. The width of the sag on the outer circumference of the obtained perforated disc-shaped SUS substrate was measured. The results are shown in Figure 7(a).

[0096] (Experimental Examples 1-2) Furthermore, a perforated disc-shaped SUS substrate was obtained in the same manner as in Experimental Example 1-1, except that the clearance width was changed to 0.015 mm. The width of the sag on the outer circumference of the obtained perforated disc-shaped SUS substrate was measured. The results are shown in Figure 7(a).

[0097] (Experimental Examples 1-3) A perforated disc-shaped stainless steel substrate was obtained in the same manner as in Experimental Example 1-1, except that the thickness of the stainless steel substrate to be processed was changed to 0.4 mm. The width of the sag on the outer circumference of the obtained perforated disc-shaped stainless steel substrate was measured. The results are shown in Figure 7(a).

[0098] (Experimental Examples 1-4) A perforated disc-shaped stainless steel substrate was obtained in the same manner as in Experimental Example 1-1, except that the thickness of the stainless steel substrate to be processed was changed to 0.4 mm and the clearance width to 0.009 mm. The width of the sag on the outer circumference of the obtained perforated disc-shaped stainless steel substrate was measured. The results are shown in Figure 7(a).

[0099] (Experimental Examples 1-5) A perforated disc-shaped stainless steel substrate was obtained in the same manner as in Experimental Example 1, except that the thickness of the stainless steel substrate to be processed was changed to 0.4 mm and the clearance width to 0.012 mm. The width of the outer periphery of the obtained perforated disc-shaped stainless steel substrate was measured. The results are shown in Figure 7(a).

[0100] (Experimental Examples 1-6) A perforated disc-shaped stainless steel substrate was obtained in the same manner as in Experimental Example 1, except that the thickness of the stainless steel substrate to be processed was changed to 0.4 mm and the clearance width to 0.015 mm. The width of the outer periphery of the obtained perforated disc-shaped stainless steel substrate was measured. The results are shown in Figure 7(a).

[0101] The results in Figure 7(a) confirmed that the width of the outer edge sag does not change with the clearance width. On the other hand, comparing Experimental Examples 1-1 to 1-2 with Experimental Examples 1-3 to 1-6, it was confirmed that the wider the metal substrate, the greater the width of the outer edge sag.

[0102] (Experimental Example 2-1) A SUS (stainless steel) substrate with a thickness of 0.3 mm was prepared for processing. Using the punching apparatus shown in Figure 6, the SUS substrate was punched to obtain a perforated disc-shaped SUS substrate with an outer diameter of 23.5 mm, an inner diameter of 15.0 mm, and an outer-to-inner diameter difference of 8.5 mm. The width of the sag on the outer circumference of the obtained perforated disc-shaped SUS substrate was measured. The results are shown in Figure 7(b).

[0103] (Experimental Example 2-2) A perforated disc-shaped stainless steel substrate with an outer diameter of 21.96 mm, an inner diameter of 9.16 mm, and an outer-to-inner diameter difference of 12.8 mm was obtained using the same method as in Experimental Example 2-1. The width of the periphery of the obtained perforated disc-shaped stainless steel substrate was measured. The results are shown in Figure 7(b).

[0104] (Experimental Example 2-3) A perforated disc-shaped stainless steel substrate with an outer diameter of 23.5 mm, an inner diameter of 15.0 mm, and an outer-to-inner diameter difference of 8.5 mm was obtained using the same method as in Experimental Example 2-1, except that the thickness of the stainless steel substrate to be processed was 0.4 mm. The width of the outer periphery of the obtained stainless steel substrate was measured. The results are shown in Figure 7(b).

[0105] (Experimental Example 2-4) A perforated disc-shaped stainless steel substrate with an outer diameter of 25.3 mm, an inner diameter of 13.8 mm, and an outer-to-inner diameter difference of 11.5 mm was obtained using the same method as in Experimental Example 2-1, except that the thickness of the stainless steel substrate to be processed was 0.4 mm. The width of the outer periphery of the obtained stainless steel substrate was measured. The results are shown in Figure 7(b).

[0106] (Experimental Examples 2-5) A perforated disc-shaped stainless steel substrate with an outer diameter of 21.96 mm, an inner diameter of 9.16 mm, and an outer-to-inner diameter difference of 12.8 mm was obtained using the same method as in Experimental Example 2-1, except that the thickness of the stainless steel substrate to be processed was 0.4 mm. The width of the outer periphery of the obtained stainless steel substrate was measured. The results are shown in Figure 7(b).

[0107] From the results in Figure 7(b) above, it was confirmed that the outer circumference sag is not dependent on the difference between the inner and outer diameters of the SUS base material. On the other hand, it was confirmed that the thicker the metal base material, the greater the outer circumference sag.

[0108] In other words, the present disclosure provides the following inventions. [1] A reflective optical scale for an encoder, comprising a disc-shaped metal substrate having a first surface and a second surface facing the first surface, and a low-reflectivity layer arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate, wherein the metal substrate has a reflectivity of at least 50% on the first surface, a thickness of 0.05 mm or more and 0.60 mm or less, and the metal substrate has a sag on the outer edge of the first surface side, with a width of 500 μm or less.

[0109] [2] The above metal substrate is a SUS substrate, as described in [1], a reflective optical scale for an encoder.

[0110] [3] The metal substrate is in the shape of a perforated disc with a central hole, as described in [1] or [2], a reflective optical scale for an encoder.

[0111] [4] The reflective optical scale for encoder according to [3], wherein the metal substrate has a sag on the inner peripheral edge of the first surface side, and the width of the sag is 500 μm or less.

[0112] [5] The reflective optical scale for encoders according to [3] or [4], wherein the difference between the outer and inner diameters of the perforated disc-shaped metal substrate is 8 mm or more and 13 mm or less.

[0113] [6] A reflective optical scale for an encoder according to any one of [1] to [5], wherein the ratio (T2 / T1) of the thickness T2 at the outer edge of the metal substrate to the thickness T1 of the metal substrate is 0.70 or more and 0.90 or less.

[0114] [7] A reflective optical scale for an encoder according to any one of [1] to [6], wherein the distance D1 between the outer surface of the metal substrate and the outer surface of the low-reflection layer is 500 μm or more and 1500 μm or less.

[0115] [8] The aforementioned metal substrate has a sag amount of 10 μm or more and 500 μm or less, a reflective optical scale for an encoder according to any one of [1] to [7].

[0116] [9] A disc-shaped metal substrate having a first surface and a second surface opposite to the first surface, A reflective optical scale for an encoder, comprising a low-reflection layer arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate, wherein the distance D1 between the outer surface of the metal substrate and the outer surface of the low-reflection layer is 500 μm or more and 1500 μm or less.

[0117]

[10] A reflective optical encoder characterized by comprising: a reflective optical scale for an encoder as described in any of [1] to [9]; a light source for irradiating the surface of the reflective optical scale for an encoder on the side where the low-reflectivity layer is located with measurement light; and a photodetector for detecting reflected light from the reflective optical scale for an encoder.

[0118]

[11] A method for manufacturing a reflective optical scale for an encoder, comprising: a step of manufacturing a multi-paneled body having a first surface and a second surface facing the first surface, wherein the reflectivity of at least the first surface is 50% or more and the thickness is 0.05 mm or more and 0.60 mm or less; a step of manufacturing a multi-paneled body having a patterned low-reflectivity layer arranged in a circular manner and multi-paneled on the first surface side of the metal substrate to be manufactured, wherein the outer peripheral punching line of the reflective optical scale for an encoder is formed outside the outer peripheral surface of the low-reflectivity layer; and a step of individualizing the multi-paneled body to obtain a reflective optical scale for an encoder by punching out the outer peripheral punching line to individualize it.

[0119]

[12] A multi-panel assembly of a reflective optical scale for an encoder, comprising: a metal substrate for processing having a first surface and a second surface facing the first surface, wherein the reflectivity of at least the first surface is 50% or more and the thickness is 0.05 mm or more and 0.60 mm or less; and a patterned low-reflectivity layer arranged in a circular manner and multi-paneled on the first surface side of the metal substrate for processing, wherein the outer edge punching line of the reflective optical scale for an encoder is formed outside the outer edge surface of the low-reflectivity layer, and the distance between the outer edge punching line of the reflective optical scale for an encoder and the outer edge surface of the low-reflectivity layer is 500 μm or more and 1500 μm or less. [Explanation of symbols]

[0120] 1 … Metal base material 2…Low reflective layer P... Who 10… Reflective optical scale for encoders 50… Reflective optical scale with multiple surfaces for encoders 100... Reflective optical encoder

Claims

[Claim 1] A disc-shaped metal substrate having a first surface and a second surface opposite to the first surface, A reflective optical scale for an encoder, comprising a low-reflection layer arranged in a pattern along the circumferential direction of the metal substrate on the first surface side of the metal substrate, The metal substrate has a reflectance of at least 50% on the first surface side, and a thickness of 0.05 mm or more and 0.60 mm or less. The metal substrate has a sag on the outer peripheral edge of the first surface, and the width of the sag is 500 μm or less. The aforementioned metal substrate is a perforated disc shape with a central hole, The difference between the outer and inner diameters of the perforated disc-shaped metal substrate is 8 mm or more and 13 mm or less. A reflective optical scale for an encoder, wherein the ratio of the thickness T2 at the outer edge of the metal substrate to the thickness T1 of the metal substrate (T2 / T1) is 0.70 or more and 0.90 or less.

Images