Reflection-type optical scale for encoder, reflection-type optical encoder, and laminate for reflection-type optical scale for encoder

Abstract

The present disclosure provides a reflective optical scale for an encoder having, in order in the thickness direction, a high reflective layer, a protective layer, and a low reflective layer provided in a pattern, the reflective optical scale for an encoder has a low-reflection region, which is a region where the low-reflection layer is provided, and a high-reflection region, which is a region where the protective layer is exposed, and satisfies formula (1), where d ([mu] m) is the film thickness of the protective layer and theta (degree) is the angle of incidence of incident light to the protective layer. D = m [lambda] / [2n * cos {Arcsin (sin [theta] / n)}] (1) (in the formula, n is the refractive index of the protective layer, [lambda] is the wavelength ([mu] m) of the incident light, and m is a number satisfying 0 < m < = 0.3 or p-0.3 < = m < = p + 0.3 (p is an integer of 1-3).

Description

Technical Field

[0001] The present invention relates to a reflective optical scale for an encoder, a reflective optical encoder, and a stacked body for a reflective optical scale for an encoder. Background Art

[0002] In the past, optical encoders were used in servo motors and the like equipped with control mechanisms. Among optical encoders, there are transmission-type encoders and reflection-type encoders, but compared with transmission-type encoders, reflection-type encoders have the following advantages: short optical path, easy miniaturization and thinning, and no need to position light-emitting elements or light-receiving elements, so they are easy to assemble. The reflection-type optical encoder includes a reflection-type optical scale, a light source such as an LED that irradiates light to the scale, and a photodetector that detects the reflected light from the scale. In the reflection-type optical scale, the reflection area (high reflection area) and the non-reflection area (low reflection area) are alternately arranged, and the reflectivity of the light in the reflection area is higher than the reflectivity of the light in the non-reflection area. As a result, the intensity of the light reflected from the scale and incident on the photodetector changes according to the position of the scale. The photodetector detects the intensity of the light generated by the movement of the position of the scale in the length measurement direction. The reflection-type optical encoder processes the displacement information of the position of the scale according to the intensity of the detected light, thereby being able to obtain position information.

[0003] In the reflective area and non-reflective area formed in the reflective optical scale, in order to prevent erroneous detection by the light detector and improve the detection accuracy of the signal, it is necessary to increase the reflectivity of the reflective area and reduce the reflectivity of the non-reflective area.

[0004] For example, Patent Document 1 discloses a reflective plate, characterized in that, in the reflective plate used for an optical encoder, a reflective film that reflects light, a protective layer that protects the reflective film, and a pattern forming film whose light reflectivity is lower than that of the reflective film and on which a slit pattern is formed are stacked in sequence on a substrate.

[0005] Patent document 2 discloses a reflective optical scale for an encoder, in which high-reflection areas and low-reflection areas are alternately arranged on a substrate for the purpose of sufficiently reducing the reflectivity in the low-reflection areas, wherein the low-reflection areas include a low-reflection portion having: a metal chromium film, which is arranged on one surface of the substrate; and a chromium oxide film and a chromium nitride film, which are arranged in different orders on the surface of the metal chromium film on the opposite side of the substrate, and the reflectivity of the high-reflection area for light incident from the side of the reflective optical scale for the encoder opposite to the substrate is higher than that of the low-reflection area.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2005-241248

[0009] Patent Document 2: WO2021 / 201024 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In the past, when a patterned low-reflection layer is formed on a high-reflection layer including a metal or the like, the low-reflection layer is directly formed on the high-reflection layer, a resist pattern is formed on the low-reflection layer, for example, by photolithography, and the resist pattern is used as a mask for etching, thereby obtaining a patterned low-reflection layer. However, when etching the low-reflection layer, sometimes the surface of the high-reflection layer is rough and the surface roughness becomes larger, or sometimes etching residue is generated on the surface of the high-reflection layer, and there is a problem of reduced reflectivity of light incident on the high-reflection area. Therefore, the inventors of the present application have studied the provision of a protective layer between the high-reflection layer and the low-reflection layer. However, it is newly discovered that even when a protective layer is provided, the reflectivity of light incident on the high-reflection area is sometimes reduced.

[0012] The present invention has been completed in view of the above-mentioned situation, and its main purpose is to provide a reflective optical scale for an encoder that can improve the reflectivity of light incident on a high-reflection area.

[0013] Means for solving problems

[0014] One embodiment of the present disclosure provides a reflective optical scale for an encoder, which has a high-reflection layer, a protective layer and a low-reflection layer arranged in a pattern in sequence in the thickness direction. The reflective optical scale for an encoder has a low-reflection area as an area where the low-reflection layer is provided and a high-reflection area as an area where the protective layer is exposed. When the film thickness of the protective layer is set to d (μm) and the incident angle of the incident light on the protective layer is set to θ (°), the following formula (1) is satisfied.

[0015] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0016] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0017] Another embodiment of the present disclosure provides a reflective optical scale for an encoder, wherein a high-reflection layer, a protective layer comprising an organic material, and a low-reflection layer arranged in a pattern are sequentially provided in the thickness direction, and the scale comprises: a low-reflection region, which is a region where the high-reflection layer, the protective layer, and the low-reflection layer are provided; and a high-reflection region, which is a region where the high-reflection layer and the protective layer are provided, the thickness of the protective layer is greater than 0.16 μm and less than 1.0 μm, and the reflectivity at the high-reflection region is greater than 40% when the wavelength of the measuring light source is set to 850 μm.

[0018] Another embodiment of the present disclosure provides a reflective optical scale for an encoder, wherein a high reflective layer, a protective layer comprising an organic material, and a low reflective layer arranged in a pattern are sequentially provided in the thickness direction, and the scale comprises: a low reflective region, which is a region where the high reflective layer, the protective layer, and the low reflective layer are provided; and a high reflective region, which is a region where the high reflective layer and the protective layer are provided, and when the wavelength of the measuring light source is set to 850 μm, the reflectivity at the low reflective region is less than 2%, and the S / N ratio represented by the following formula is greater than 30.

[0019] S / N ratio = reflectivity of high reflection area / reflectivity of low reflection area

[0020] Another embodiment of the present disclosure provides a reflective optical encoder, characterized in that it comprises: a reflective optical scale for the encoder; a light source for irradiating measuring light onto the surface of the reflective optical scale for the encoder on the side where the low-reflective layer is arranged; and a light detector for detecting reflected light from the reflective optical scale for the encoder.

[0021] Another embodiment of the present invention provides a stacked body for a reflective optical scale for an encoder, which is a stacked body for a reflective optical scale for an encoder used to manufacture the above-mentioned reflective optical scale for an encoder, wherein the stacked body has a high-reflection layer, a protective layer and a layer for forming a low-reflection layer in sequence in the thickness direction, and when the film thickness of the above-mentioned protective layer is set to d (μm) and the incident angle of the incident light on the above-mentioned protective layer is set to θ (°), the following formula (1) is satisfied.

[0022] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0023] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0024] Another embodiment of the present disclosure provides a stacked body for a reflective optical scale for an encoder, which is a stacked body for a reflective optical scale for an encoder used to manufacture the above-mentioned reflective optical scale for an encoder, wherein the stacked body has a high-reflection layer and a protective layer in sequence in the thickness direction, and when the film thickness of the above-mentioned protective layer is set to d (μm) and the incident angle of the incident light on the above-mentioned protective layer is set to θ (°), the following formula (1) is satisfied.

[0025] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0026] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0027] Effects of the Invention

[0028] In the present disclosure, the following effect is achieved: a reflective optical scale for an encoder can be provided that is capable of improving the reflectivity of light incident on a high-reflection area. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic cross-sectional view illustrating a reflective optical scale for an encoder in the present disclosure.

[0030] Figure 2 It is a schematic perspective view and a partially enlarged view illustrating a reflective optical encoder in the present disclosure.

[0031] Figure 3 This is a schematic cross-sectional view illustrating a reflective optical scale for an encoder in the present disclosure.

[0032] Figure 4 This is a schematic cross-sectional view illustrating a reflective optical scale for an encoder in the present disclosure.

[0033] Figure 5 Graph showing the relationship between the film thickness of the protective layer and the average reflectance in Experimental Examples A and B.

[0034] Figure 6 Graph showing the relationship between the film thickness of the protective layer and the average standard reflectance in Experimental Examples A and B.

[0035] Figure 7 These are the measurement results of reflectance when the wavelength and incident angle of the measurement light of Example and Reference Example 1 were changed.

[0036] Figure 8 The following are the measurement results of reflectance when the wavelength and incident angle of the measurement light of Comparative Examples 1 and 2 were changed.

[0037] Fig. 9 It is a schematic cross-sectional view of a stacked body for a reflective optical scale for an encoder in the present disclosure. DETAILED DESCRIPTION

[0038] The present disclosure includes a reflective optical scale for an encoder, a reflective optical encoder, and a laminate for a reflective optical scale for an encoder in an embodiment. The embodiments of the present disclosure are described below with reference to the accompanying drawings, etc. However, the present disclosure can be implemented in a variety of different ways, and is not limited to the description of the embodiments illustrated below for explanation. In addition, with respect to the accompanying drawings, in order to make the description clearer, the width, thickness, shape, etc. of each part are sometimes schematically shown compared to the actual form, but this is just an example and does not limit the interpretation of the present disclosure. In addition, in this specification and each figure, for figures that have already appeared, the same elements as the previous ones are marked with the same numbers, and the detailed description is sometimes appropriately omitted.

[0039] In this specification, when describing the configuration of other components on a certain component, if simply described as "on..." or "below...", unless otherwise specified, this includes both the case where the other components are configured directly above or directly below the certain component in a manner of contacting the certain component, and the case where the other components are configured above or below the certain component with another component interposed therebetween. In addition, in this specification, when describing the configuration of other components on the surface of a certain component, if simply described as "on the side of..." or "on the surface of...", unless otherwise specified, this includes both the case where the other components are configured directly above or directly below the certain component in a manner of contacting the certain component, and the case where the other components are configured above or below the certain component with another component interposed therebetween.

[0040] In addition, in this specification, the "reflective optical scale for encoder" is sometimes simply referred to as the "optical scale".

[0041] As described above, the inventors of the present application have studied the problem that the reflectivity of light incident on the high reflection area is reduced even when a protective layer is provided between the high reflection layer and the low reflection layer. As a result, it has been found that the reflectivity of light incident on the high reflection area can be increased by adjusting the film thickness of the protective layer to a predetermined range in which light reflected on the surface of the protective layer and light reflected on the interface between the protective layer and the high reflection layer are mutually enhanced, thereby completing the present invention.

[0042] Hereinafter, the reflective optical scale for encoder, the reflective optical encoder and the stacked body for reflective optical scale for encoder in the present disclosure will be described in detail.

[0043] A-1. Reflective optical scale for encoder

[0044] Figure 1 (a) is a schematic cross-sectional view showing an example of a reflective optical scale for an encoder in the present disclosure. Figure 1 The encoder shown in (a) uses a reflective optical scale 10 in the thickness direction D T The high-reflection layer 1, the protective layer 2, and the low-reflection layer 3 provided in a pattern are provided in order, and the low-reflection region R1 is a region provided with the low-reflection layer 3 and the high-reflection region R2 is a region where the protective layer 2 is exposed. The present disclosure is characterized in that the film thickness d of the protective layer 2 satisfies a prescribed range. Figure 1 The encoder of (a) is provided with a reflective optical scale having low reflection areas R1 and high reflection areas R2 alternately. The low reflection area R1 has a high reflection layer 1, a protective layer 2 and a low reflection layer 3. The high reflection area R2 has a high reflection layer 1 and a protective layer 2. In addition, Figure 1 (b) shows the measurement of light from Figure 1 (a) is a case where the encoder is incident on the low-reflection layer 3 side of the reflective optical scale 10. The light L1 irradiated from the light source is reflected on the surface of the protective layer 2 and the interface between the high-reflection layer 1 and the protective layer 2. The reflectivity of the light at the high-reflection area R2 is higher than the reflectivity of the light at the low-reflection area R1. It should be noted that the reflectivity of the light at the high-reflection area R2 and the reflectivity of the light at the low-reflection area R1 represent the reflectivity at the same wavelength and the same incident angle.

[0045] Figure 2 (a) is a schematic stereoscopic diagram showing an example of a reflective optical encoder having a reflective optical scale for an encoder according to the present disclosure, Figure 2 (b) is viewed from above Figure 2 (a) is a partial enlarged view of a reflective optical encoder. The reflective optical encoder 100 in the present disclosure includes a reflective optical scale 10 for an encoder, a light source 21 and a light detector 22. Figure 2 In (a), the fixed slit 23 is arranged between the light detector 22 and the reflective optical scale 10 for the encoder.

[0046] The reflective optical scale for the encoder disclosed in the present invention can improve the reflectivity of light incident on the high-reflection area by adjusting the film thickness d of the protective layer 2 to a specified range.

[0047] The following is a detailed description of the reflective optical scale for the encoder disclosed in the present invention.

[0048] 1. Protective layer

[0049] The protective layer in the present disclosure is disposed between the high-reflection layer and the low-reflection layer. The protective layer has transparency and has the function of protecting the high-reflection layer. By providing the protective layer, when etching the low-reflection layer into a pattern, there is no need to worry about the surface roughness of the high-reflection layer becoming rough and the surface roughness becoming larger. Therefore, diffuse reflection of light can be suppressed.

[0050] In the present disclosure, when the incident angle of incident light on the protective layer is θ (°), the thickness d (μm) of the protective layer is adjusted so as to satisfy the following formula (1).

[0051] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0052] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0053] It should be noted that the reason why the reflectivity of light incident on the high reflection area can be increased by setting the thickness of the protective layer to the above range is as follows. The refractive index is in the relationship of air < ​​protective layer < high reflection layer, so it becomes a fixed end reflection at each interface, and the phase will shift by π. When the phase of the light reflected at the interface between the air and the protective layer is consistent with the phase of the light reflected at the interface between the protective layer and the high reflection layer, the reflected light can best suppress the attenuation of the reflectivity. The condition for the phase consistency of the reflected light is when the film thickness satisfies the above formula.

[0054] In the above formula (1), the incident angle θ is the incident angle of the incident light on the protective layer. As described later, the optical scale 10 sometimes has different incident angles of light depending on its position relative to the light source 21 ( Figure 3 ). The incident angle θ in the above formula (1) is the incident angle at the scale position (such as the position of the main pattern) where the strongest reflectivity is desired, and can be, for example, 0°, 20°, 40°, or 55°.

[0055] In the above formula (1), n ​​is the refractive index of the protective layer, and λ is the wavelength (μm) of the incident light, for example, any wavelength within the range of 0.38 μm to 1.0 μm, or any wavelength within the range of 0.50 μm to 1.0 μm.

[0056] In the above formula (1), m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer of 1 to 3). p is 1, 2 or 3, preferably 1 or 2, and more preferably 1.

[0057] like Figure 2 As shown in (b), the optical scale 10 sometimes has a different angle of incidence of light depending on its position relative to the light source 21. Figure 3 (a) and Figure 3 (b) are used to illustrate Figure 2 Schematic cross-sectional view of the optical ruler of the incident angle of light at P1 and the incident angle of light at P2 in (b). Figure 3 (a) and Figure 3 As shown in (b), the incident angle θ1 of light at position P1 is larger than the incident angle θ2 of light at position P2 close to the light source 21. The incident angle is the angle between the perpendicular line of the surface of the protective layer and the emission direction of the light L1 from the light source.

[0058] As described above, the inventors of the present application have newly discovered that the deviation of the reflectivity sometimes increases depending on the position of the high-reflection area in the optical scale. In the present disclosure, m in the above formula (1) is preferably greater than 0 and less than 0.3, greater than 0.7 and less than 1.3, greater than 1.9 and less than 2.3, or greater than 3.0 and less than 3.3. By making m within the above range, the deviation of the reflectivity caused by the position of the high-reflection area as described above can also be reduced.

[0059] The material of the protective layer is not particularly limited as long as it has transparency and can protect the high reflective layer, and may be any of an organic material and an inorganic material, but an organic material is preferred.

[0060] The reason is that the etching process for adjusting the shape of the optical scale to a predetermined shape is easy, and although it also depends on the type of the high reflective layer, the adhesion to the high reflective layer is excellent compared to inorganic materials. In addition, the protective layer composed of organic materials has excellent antifouling properties, so impurities (pollutants) are not easy to adhere to the surface, and the adhesion of the protective layer on the side opposite to the substrate to other layers is also good.

[0061] Furthermore, compared with inorganic materials, the generation of cracks can sometimes be suppressed, and the thickness can be easily adjusted to the above-mentioned prescribed thickness. In addition, compared with inorganic materials, it is also excellent in terms of cost. Furthermore, compared with inorganic materials, the contact angle becomes higher, so the antifouling function is improved. Specifically, the contact angle of the protective layer to water can be set to the range described later.

[0062] In the present disclosure, the protective layer may be a single layer or may be composed of two or more layers. When the protective layer is composed of two layers, from the viewpoint of antifouling properties, it is preferred that a protective layer composed of an organic material is disposed on the outermost surface side (the side opposite to the substrate), and a protective layer composed of an inorganic material is disposed on the other side.

[0063] The organic material preferably includes a resin. As the resin used for the protective layer, there is no particular limitation as long as it is a resin that can obtain a transparent protective layer. For example, ionizing radiation curing resins cured by irradiation with ionizing radiation such as ultraviolet rays and electron beams, thermosetting resins cured by heating, etc. can be listed. Specifically, preferably novolac resins, polyolefin resins, polyester resins, urethane resins, polyimide resins, acrylic resins, epoxy resins. As novolac resins, phenol novolac resins are preferred. This is because: its electrical properties are excellent and the adverse conditions caused by charging can be suppressed. As acrylic resins, trifunctional or higher acrylates such as pentaerythritol tetraacrylate and dipentaerythritol tetraacrylate are preferred. This is because it can improve photocurability. As epoxy resins, epoxy acrylate resins with fluorene structures are preferred. This is because it can improve heat resistance, adhesion, and chemical resistance. As epoxy resins, phenolphthalein (cardo) epoxy resins are also preferred. This is because it can impart excellent transparency, heat resistance, surface hardness, and flatness. The organic material may contain a polymerization initiator, various additives, and the like in addition to the resin.

[0064] As the inorganic material, inorganic compounds can be cited. As the inorganic compound, for example, oxides, oxynitrides, nitrides, oxycarbides, and oxycarbide-nitrides of metal elements or non-metal elements such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, titanium, boron, yttrium, zirconium, cerium, and zinc can be cited. Silicon dioxide (SiO2) is particularly preferred. The inorganic compound can be used alone or in any proportion.

[0065] The protective layer is preferably in direct contact with the high reflective layer. In addition, the refractive index of the protective layer is preferably smaller than the refractive index of the high reflective layer. The refractive index of the protective layer is, for example, greater than 1.1 and less than 3.0, greater than 1.1 and less than 1.65, or greater than 1.5 and less than 1.65.

[0066] In addition, the above refractive index refers to the refractive index of light with respect to the peak wavelength of the light source. The refractive index refers to the value obtained by dividing the speed of light in a vacuum by the speed of light in a substance (more accurately, the phase velocity), and is an indicator of the travel mode of light in a substance. The refractive index can be measured by using an ellipsometer. An ellipsometer is an analytical device that measures the change in the polarization state of incident light and reflected light relative to a sample.

[0067] The protective layer is preferably water-repellent. Even if water containing a substance that causes dirt is attached to the surface of the protective layer, the substance that causes dirt can be removed by repelling water. Therefore, the reduction in reflectivity caused by dirt adhering to the high-reflection area can be suppressed.

[0068] The contact angle of the protective layer to water in the present disclosure is, for example, 50 degrees or more and 90 degrees or less, preferably 62 degrees or more and 90 degrees or less, and more preferably 73 degrees or more and 90 degrees or less.

[0069] When the contact angle to water is within the above range, the antifouling property is improved. On the other hand, when the contact angle to water is less than the above range, the water repellency becomes insufficient, and thus it is possible that excellent antifouling property cannot be obtained. On the other hand, when the contact angle to water is greater than the above range, when an organic film is used for the low-reflection layer, unfavorable conditions such as depressions may occur during coating, which may become a cause of defects.

[0070] Here, the contact angle with respect to water is measured in accordance with the provisions of JIS R3257:1999.

[0071] 2. High reflective layer

[0072] The high reflection layer in the present disclosure has high reflectivity. Examples of such a high reflection layer include a metal substrate and a metal film disposed on one surface of a substrate.

[0073] Examples of the metal substrate include a stainless steel (hereinafter referred to as SUS) substrate, an aluminum substrate, and a copper substrate.

[0074] In the present disclosure, it is preferred to use a SUS substrate. Since SUS contains metallic chromium, when a low-reflection layer containing a metallic chromium film is directly provided in a pattern on a SUS substrate, it is easy to be roughened by etching, and etching residues of metallic chromium are easy to be generated. Therefore, the effect brought about by forming a protective layer, that is, the effect of suppressing the surface roughness of the high-reflection layer caused by etching and the effect of suppressing the generation of etching residues can be more significantly obtained.

[0075] The lower limit of the thickness of the metal substrate is preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. On the other hand, the upper limit of the thickness of the metal substrate is preferably 0.5 mm or less.

[0076] The high reflection layer in the present disclosure may be a metal film disposed on one surface of the substrate.

[0077] As the substrate used in this case, glass, resin, etc. can be cited. In addition to the above, "metal different from the metal film" can also be used for the substrate. Among them, a glass substrate using glass is preferred. The reason is that the linear expansion coefficient of glass is small, which can suppress the dimensional change accompanying the temperature change of the use environment.

[0078] In addition, the metal film is preferably made of a metal with high reflectivity. Examples of the metal include chromium, silver, aluminum, rhodium, gold, copper, and alloys containing these metals as main components. Among them, a metal chromium film is preferred. A metal chromium film is a layer containing metal chromium.

[0079] The thickness of the metal film is, for example, not less than 0.05 μm and not more than 0.3 μm, or may be not less than 0.1 μm and not more than 0.2 μm.

[0080] 3. Low reflection layer

[0081] The low reflection layer in the present disclosure is provided in a pattern on the side of the protective layer opposite to the high reflection layer. As the low reflection layer, the composition is not particularly limited as long as the reflectivity of light incident on the low reflection area is less than the reflectivity of light incident on the high reflection area. For example, the low reflection layer may be an inorganic film or an organic film.

[0082] In the present invention, it is preferred to have a three-layer structure of a metal chromium film and a chromium oxide film and a chromium nitride film formed in different orders on the metal chromium film from the high reflection layer side. If it is such a low reflection layer, the reflectivity of light incident on the low reflection area can be reduced to less than 10%, preferably less than 5%, and further less than 1% at any wavelength in the wavelength range of 380nm to 1000nm, especially in the wavelength range of 500nm to 1000nm. On the other hand, the reflectivity of the above-mentioned low reflection area is, for example, more than 0%. Specifically, the above-mentioned reflectivity of the above-mentioned low reflection area is, for example, more than 0% and less than 10%, preferably more than 0% and less than 5%, more preferably more than 0% and less than 1%, and particularly more preferably more than 0% and less than 0.5%.

[0083] It should be noted that the reflectivity of the low-reflection region preferably satisfies the above range at any angle within the range of the incident angle of 5° to 70°. Therefore, the difference between the reflectivity at the high-reflection region and the reflectivity at the low-reflection region can be increased. In addition, if only metallic chromium is prepared, a chromium oxide film and a chromium nitride film can be easily formed by using reactive sputtering or the like. Furthermore, high-precision patterning can also be easily performed compared to silicon oxide film.

[0084] In this specification, "chromium oxide film and chromium nitride film formed in different orders on the metal chromium film" means: the metal chromium film, chromium oxide film and chromium nitride film can be formed in this order, or the metal chromium film, chromium nitride film and chromium oxide film can be formed in this order.

[0085] For example, Figure 4 The low reflection layer 3 of the reflective optical scale 10 for encoder shown in (a) comprises a metal chromium film 3c, a chromium nitride film 3b formed on the metal chromium film 3c, and a chromium oxide film 3a formed on the chromium nitride film 3b. Figure 4The low-reflection layer 3 of the reflective optical scale 10 for encoder shown in (b) includes a metal chromium film 3c, a chromium oxide film 3a formed on the metal chromium film 3c, and a chromium nitride film 3b formed on the chromium oxide film 3a.

[0086] 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 is particularly preferably the surface of the chromium oxide film, because this can more effectively reduce the reflectivity in the low reflection region.

[0087] Hereinafter, “a low-reflection layer including a metal chromium film, a chromium nitride film, and a chromium oxide film in sequence” is referred to as a low-reflection layer of the first specification, and “a low-reflection layer including a metal chromium film, a chromium oxide film, and a chromium nitride film in sequence” is referred to as a low-reflection layer of the second specification.

[0088] (i) Low reflection layer of the first specification

[0089] The low-reflection layer of this specification is configured with a metal chromium film, a chromium nitride film, and a chromium oxide film in order from the substrate side. The low-reflection area of ​​the low-reflection layer of this specification can reduce the reflectivity at any wavelength within the wavelength range of 380nm and 1000nm, especially 500nm and 1000nm of light irradiated from the light source to less than 5%, especially less than 0.5%, and the reflectivity changes relatively smoothly with respect to the change in wavelength, making it easy to control the reflectivity. Specifically, the above-mentioned reflectivity can be reduced to more than 0% and less than 5%, especially to more than 0% and less than 0.5%. Below, each layer is described in detail.

[0090] (a) Metal chromium film

[0091] In this specification, the metal chromium film is provided on the protective layer. The metal chromium film is a layer containing metal chromium. The metal chromium film is a layer that does not substantially transmit light irradiated from a light source, and its transmittance is preferably 1.0% or less. The transmittance can be measured using a spectrophotometer (MPC-3100) manufactured by Shimadzu Corporation. The film thickness is, for example, greater than 40 nm, preferably greater than 70 nm. Specifically, the above-mentioned film thickness is, for example, greater than 40 nm and less than 500 nm, preferably greater than 70 nm and less than 200 nm.

[0092] Here, the "thickness" of each component refers to the thickness obtained by a general measurement method. As a method for measuring thickness, for example, a stylus method in which the thickness is calculated by drawing and detecting the concave and convex on the surface with a stylus, or an optical method in which the thickness is calculated based on a spectral reflection spectrum, etc. can be cited. Specifically, the thickness can be measured using a stylus film thickness meter P-15 manufactured by KLA-Tencor Co., Ltd. It should be noted that as the thickness, the average value of the thickness measurement results at multiple locations of the component as the object can be used.

[0093] As a method for forming the metal chromium film, for example, a physical vapor deposition method (PVD) such as a sputtering method, an ion plating method, or a vacuum deposition method is used.

[0094] (b) Chromium nitride film

[0095] The chromium nitride film in this specification is arranged between the metal chromium film and the chromium oxide film. Unlike chromium oxynitride, chromium oxynitride carbide, etc., the main components of the chromium nitride film are chromium and nitrogen, and it does not contain impurities other than chromium and nitrogen.

[0096] The x representing the atomic ratio of Cr to N in the chromium nitride (CrNx) film is preferably 0.4 or more and 1.1 or less.

[0097] In addition, regarding the chromium nitride film, the ratio of chromium to nitrogen is within a range of 80% to 100% with the entire film being 100 atomic %, and a purity within a range of 90% to 100% is preferred. Impurities may include, for example, hydrogen, oxygen, carbon, and the like.

[0098] The thickness of the chromium nitride film (T N ) is preferably in the range of 5 nm to 100 nm, and particularly preferably in the range of 10 nm to 80 nm. O ), when the wavelength is 850nm, T N With T O The total of is preferably 40 nm or more. When the wavelength is 550 nm, T N With T O The total of is preferably 20 nm or more. If the film thickness is within this range, the reflectivity in the low reflection region can be easily reduced to 10% or less, especially 5% or less, compared with the case outside the above range. Specifically, the above reflectivity can be reduced to 0% or more and 10% or less, especially 0% or more and 5% or less. Furthermore, the film thickness (T N) tends to reduce the reflectivity in the entire purple to infrared (approximately 380nm to 1000nm) region, especially in the entire green to infrared (approximately 500nm to 1000nm) region, so it is preferably in the range of 10nm to 80nm.

[0099] As a method for forming chromium nitride, for example, a physical vapor deposition method (PVD) such as a reactive sputtering method, an ion plating method, and a vacuum evaporation method is used. When using the reactive sputtering method, nitrogen can be introduced into argon (Ar) gas, and a chromium nitride film can be formed by a 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.

[0100] (c) Chromium oxide film

[0101] The chromium oxide film is formed on the chromium nitride film, and its main components are chromium and oxygen. Unlike chromium oxynitride, chromium oxynitride carbide, etc., it does not substantially contain impurities other than chromium and oxygen.

[0102] The y representing the atomic ratio of Cr to O in the chromium oxide (CrOy) film is preferably 1.4 or more and 2.1 or less.

[0103] Specifically, for the chromium oxide film, the entire film is 100 atomic %, and the ratio of chromium to oxygen is in the range of 80% to 100%, wherein the purity is preferably in the range of 90% to 100%. As impurities, hydrogen, nitrogen, carbon, etc. may also be included.

[0104] The film thickness of the chromium oxide film is not particularly limited, but is preferably in the range of 5 nm to 100 nm, and particularly preferably in the range of 10 nm to 80 nm. O ) and the thickness of the chromium nitride film (T N ) is preferably within the range described in the above “(i) Low-reflection layer of the first specification (b) Chromium nitride film”. Furthermore, regarding the film thickness (T O ), in order to easily reduce the reflectivity in the entire region of the purple to infrared (about 380nm to 1000nm), especially in the entire region of the green to infrared (about 500nm to 1000nm), it is preferably within the range of 10nm to 65nm

[0105] As a method for forming chromium oxide, for example, a physical vapor deposition method (PVD) such as a reactive sputtering method, an ion plating method, and a vacuum evaporation method is used. When using the reactive sputtering method, oxygen can be introduced into argon (Ar) gas, and a chromium oxide film can be formed by a reactive sputtering method using a Cr target. At this time, the composition of the chromium oxide film can be controlled by controlling the ratio of Ar gas to oxygen gas.

[0106] (ii) Second specification low reflection layer

[0107] The low-reflection layer of this specification is configured with a metal chromium film, a chromium oxide film, and a chromium nitride film in order from the protective layer side. The low-reflection region of the low-reflection layer of this specification can reduce the reflectivity at any wavelength within the range of 380nm to 1000nm, especially 500nm to 1000nm, of the light irradiated from the light source to 5% or less, especially 1% or less. Specifically, the above reflectivity can be reduced to 0% to 5%, especially 0% to 1%. Below, each layer is described in detail.

[0108] (a) Metal chromium film

[0109] The metal chromium film in this specification is formed on a substrate. The details of the metal chromium film are the same as those in the above-mentioned "(i) Low reflection layer of the first specification (a) Metal chromium film", so the description here is omitted.

[0110] (b) Chromium oxide film

[0111] The chromium oxide film in this specification is arranged between the metal chromium film and the chromium nitride film. The film thickness is not particularly limited, for example, it is preferably in the range of 5 nm to 60 nm, and particularly preferably in the range of 10 nm to 50 nm. Furthermore, it is preferred to satisfy the relationship with the film thickness of the chromium nitride film described later. This is because the reflectivity at any wavelength in the wavelength region of the low reflection region in the range of 380 nm to 1000 nm, particularly in the range of 500 nm to 1000 nm, can be more reliably reduced to 10% or less, particularly 5% or less. Specifically, the above reflectivity can be reduced to 0% or more and 10% or less, particularly to 0% or more and 5% or less.

[0112] Furthermore, regarding the film thickness (T O ), it is easy to reduce the reflectivity of the entire region of the purple to infrared (380nm and 1000nm) region, especially the entire region of the green to infrared (500nm and 1000nm) region, so it is preferably within the range of 5nm and 35nm.

[0113] The other physical properties, composition and details of the formation method of the chromium oxide film are the same as those of the above-mentioned "(i) Low-reflection layer of the first specification (c) Chromium oxide film", and therefore the description here is omitted.

[0114] (c) Chromium nitride film

[0115] The chromium nitride film of this specification is formed on the chromium oxide film. The film thickness of the chromium nitride film of this specification is not particularly limited, 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, in the range of the film thickness (T O ), when the wavelength is 850nm, T N With T O The total of is preferably 30 nm or more. When the wavelength is 550 nm, T N With T O The total of is preferably 15 nm or more. In addition, regarding the film thickness (T N ), which can easily reduce the reflectivity in the entire area from purple to infrared (about 380nm to 1000nm), especially in the entire area from green to infrared (about 500nm to 1000nm), so it is preferably in the range of 10nm to 60nm.

[0116] The method for forming the low-reflection layer disclosed in the present invention is not particularly limited, and can be manufactured by selective etching or lift-off. Specifically, on a protective layer arranged on a high-reflection layer, a metal chromium film is formed, for example, by sputtering, and then a chromium nitride film and a chromium oxide film are formed. Next, the metal chromium film, the chromium nitride film, and the chromium oxide film are patterned by photolithography and etching, thereby being able to manufacture a patterned low-reflection layer. As etching, dry etching based on plasma etching, which is constituted by plasmaizing a reaction gas containing chlorine and oxygen by a high-frequency electric field, or wet etching based on a cerium ammonium nitrate solution can be cited.

[0117] In addition, as another method, a resist pattern is formed on the protective layer, and a metal chromium film, a chromium nitride film, and a chromium oxide film are formed using a known vacuum film forming method such as a sputtering method. Then, the metal chromium film, the chromium nitride film, and the chromium oxide film formed directly on the resist pattern are removed, thereby obtaining patterns of the chromium nitride film and the chromium oxide film.

[0118] 4. Low reflective area

[0119] Regarding the low-reflection region of the present disclosure, the reflectivity at any wavelength in the wavelength region of 380 nm to 1000 nm, especially in the wavelength region of 500 nm to 1000 nm, is, for example, 10% or less, 5% or less, 2% or less, 1.5% or less, or 1% or less. Specifically, the above-mentioned reflectivity of the low-reflection region in the present disclosure is, for example, 0% or more and 10% or less, 0% or more and 5% or less, 0% or more and 2% or less, 0% or more and 1.5% or less, or 0% or more and 1% or less. It should be noted that the reflectivity of the low-reflection region preferably satisfies the above-mentioned range at any angle within the range of an incident angle of 0° or more and 70° or less. The outermost surface of the low-reflection region is preferably the surface of a chromium oxide film or a chromium nitride film of a low-reflection layer, and is particularly preferably the surface of a chromium oxide film. This is because the reflectivity in the low-reflection region can be more effectively reduced.

[0120] 5. Highly reflective areas

[0121] The high reflection area in the present disclosure is an area where the above-mentioned protective layer is exposed, and the reflectivity of light incident from the low reflection layer side of the reflective optical scale for encoder is higher than that of the low reflection area.

[0122] Regarding the high reflection region, when the incident light is any wavelength in the range of 380 nm to 1000 nm, particularly in the range of 500 nm to 1000 nm, the reflectivity is preferably 50% or more, more preferably 60% or more, within the range of the incident angle of 0° to 70°. Specifically, the reflectivity of the high reflection region in the present disclosure is, for example, 50% or more and 100% or less, preferably 60% or more and 100% or less.

[0123] 6.S / N ratio

[0124] As described above, the reflective optical scale for the encoder in the present disclosure can improve the reflectivity of the high-reflective area, thereby improving the S / N ratio represented by the following formula.

[0125] S / N ratio = reflectivity of high reflection area / reflectivity of low reflection area

[0126] It should be noted that the reflectivity of the high reflection region and the reflectivity of the low reflection region in the above formula represent reflectivity at the same wavelength and the same incident angle.

[0127] In the present disclosure, the S / N ratio may be 30 or more, particularly 35 or more, preferably 40 or more, and particularly preferably 60 or more.

[0128] 7. Optical ruler

[0129] The optical scale in the present disclosure can be used for a rotary encoder or a linear encoder. Among them, it is preferably used for a rotary encoder. The top view shape of the optical scale is not limited. For example, the shape for a rotary encoder can be roughly annular or roughly circular, and the shape for a linear encoder can be roughly rectangular.

[0130] The manufacturing method of the optical scale in the present disclosure, for example, includes: a process of preparing the above-mentioned high-reflection layer; a process of forming the above-mentioned protective layer on the high-reflection layer; and a process of forming a low-reflection layer in a pattern on the side of the protective layer opposite to the side of the high-reflection layer.

[0131] A-2. Other methods of reflective optical scales for encoders

[0132] The present disclosure also includes other methods of the reflective optical scale for encoder that are different from the method described in the above-mentioned "A-1. Reflective optical scale for encoder".

[0133] 1. The first other method

[0134] The first other method disclosed in the present invention is a reflective optical scale for an encoder, wherein a high-reflection layer, a protective layer comprising an organic material, and a low-reflection layer arranged in a pattern are provided in sequence in the thickness direction, and the scale comprises: a low-reflection region, which is a region where the high-reflection layer, the protective layer, and the low-reflection layer are provided; and a high-reflection region, which is a region where the high-reflection layer and the protective layer are provided, the thickness of the protective layer is greater than 0.16 μm and less than 1.0 μm, and the reflectivity at the high-reflection region when the wavelength of the measuring light source is set to 850 μm is greater than 40%.

[0135] In this embodiment, since the film thickness of the protective layer is within the above-mentioned range, even when the protective layer made of an organic material is provided on the high reflective layer, high reflectivity can be maintained.

[0136] In this embodiment, the protective layer includes an organic material. The organic material is the same as that described in the above-mentioned "A-1. Reflective optical scale for encoder", so the description here is omitted.

[0137] In this embodiment, the protective layer has a thickness of 0.16 μm or more and 1.0 μm or less.

[0138] The lower limit of the film thickness of the protective layer in this embodiment is not particularly limited as long as it is 0.16 μm or more, preferably 0.18 μm or more, and more preferably 0.20 μm or more. In addition, the upper limit of the film thickness of the protective layer is not particularly limited as long as it is 1.0 μm or less, preferably 0.6 μm or less, and more preferably 0.33 μm or less.

[0139] In this embodiment, when the wavelength of the measurement light source is 850 μm, the reflectance in the high reflection region is 40% or more, preferably 45% or more, and more preferably 50% or more.

[0140] Except for aspects related to the material of the above-mentioned protective layer, aspects related to the film thickness of the above-mentioned protective layer, and aspects related to the reflectivity in the above-mentioned high-reflection area when the wavelength of the measuring light source is set to 850μm, the present method is the same as the contents described in the above-mentioned "A-1. Reflective optical scale for encoder", and therefore the description here is omitted.

[0141] 2. Second other method

[0142] The second other method disclosed in the present invention is a reflective optical scale for an encoder, wherein a high reflective layer, a protective layer comprising an organic material, and a low reflective layer arranged in a pattern are provided in sequence in the thickness direction, and the scale comprises: a low reflective region, which is a region where the high reflective layer, the protective layer, and the low reflective layer are provided; and a high reflective region, which is a region where the high reflective layer and the protective layer are provided, and when the wavelength of the measuring light source is set to 850 μm, the reflectivity at the low reflective region is less than 2%, and the S / N ratio represented by the following formula is greater than 30.

[0143] S / N ratio = reflectivity of high reflection area / reflectivity of low reflection area

[0144] In this method, the S / N ratio is greater than 30, that is, the difference between the reflectivity in the high-reflection area and the reflectivity in the low-reflection area is large, so it is possible to prevent erroneous detection by the light detector. As a result, for a reflective optical encoder, the optical scale is easy to read and has good encoder characteristics.

[0145] In this embodiment, the protective layer includes an organic material. The organic material is the same as that described in the above-mentioned "A-1. Reflective optical scale for encoder", so the description here is omitted.

[0146] In the present embodiment, the S / N ratio is 30 or more, more preferably 35 or more, particularly preferably 40 or more, and particularly preferably 60 or more.

[0147] In the present embodiment, the reflectance in the low reflection region when the wavelength of the measurement light source is 850 μm is not particularly limited as long as it is 2% or less, but is preferably 1% or less, and particularly preferably 0.5% or less.

[0148] Except for aspects related to the material of the above-mentioned protective layer, aspects related to the above-mentioned S / N ratio, and aspects related to the reflectivity in the above-mentioned low-reflection area when the wavelength of the measuring light source is set to 850μm, the present method is the same as the contents described in the above-mentioned "A-1. Reflective optical scale for encoder", and therefore the description here is omitted.

[0149] B. Reflective optical encoder

[0150] In the present disclosure, a reflective optical encoder is provided, characterized in that it comprises: the above-mentioned reflective optical scale for encoder; a light source for irradiating measuring light onto the surface of the side of the reflective optical scale for encoder on which the above-mentioned low-reflective layer is arranged; and a light detector for detecting reflected light from the above-mentioned reflective optical scale for encoder. Figure 2 (a) is a schematic perspective view showing an example of a reflective optical encoder of the present disclosure. Figure 2 (a) is described in the above-mentioned "A. Reflective optical scale for encoder", so the description here is omitted. The encoder disclosed in the present invention has the above-mentioned reflective optical scale for encoder, so the difference between the reflectivity in the high-reflection area and the reflectivity in the low-reflection area is large, thereby preventing erroneous detection by the light detector 22. As a result, for the reflective optical encoder 100, the optical scale 10 is easy to read and has good encoder characteristics.

[0151] 1. Reflective optical scale for encoder

[0152] The reflective optical scale for encoder is the same as that described in the above-mentioned "A. Reflective optical scale for encoder", so the description here is omitted.

[0153] 2. Light source

[0154] As a light source, for example, it is an LED (light emitting diode), a laser, etc. The wavelength λ of the light L1 irradiated from the light source can be, for example, in the violet to infrared (about 380 to 1000nm) region, or in the green to infrared (about 500nm to 1000nm) region. The incident angle of the light relative to the optical scale 10 is, for example, greater than 0° and less than 70°.

[0155] The wavelength λ of the light L1 of the light source used in the present disclosure is approximately the same as the wavelength λ of the light used in the above-mentioned “A. Reflective optical scale for encoder” to determine the film thickness of the protective layer.

[0156] 3. Light detector

[0157] The photodetector detects light reflected by the optical scale and includes, for example, a light receiving element (eg, a photoelectric conversion element) such as a photodiode or an imaging element.

[0158] 4. Others

[0159] The reflective optical encoder disclosed in the present invention may also include a fixed gap between the light detector and the reflective optical scale for the encoder. By providing a fixed gap, the change in the amount of light received by the light detector becomes larger, which can improve the detection sensitivity. The fixed gap may also be provided between the light source and the reflective optical scale for the encoder.

[0160] C-1. Laminated body for reflective optical scale for encoder

[0161] Fig. 9 It is a schematic cross-sectional view of a stacked body for a reflective optical scale for an encoder in the present disclosure. Fig. 9 The shown stacked body 50 for a reflective optical scale for an encoder is a stacked body for a reflective optical scale for an encoder used to manufacture the above-mentioned reflective optical scale for an encoder, wherein a high-reflection layer 1, a protective layer 2 and a layer 30 for forming a low-reflection layer are sequentially provided in the thickness direction D. When the film thickness of the above-mentioned protective layer is set to d (μm) and the incident angle of the incident light to the above-mentioned protective layer is set to θ (°), the following formula (1) is satisfied.

[0162] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0163] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0164] The film thickness of the protective layer of the laminate for the reflective optical scale for encoder is within the above-specified range, and therefore, by patterning the layer for forming the low-reflection layer, the reflective optical scale for encoder can be manufactured to improve the reflectivity of light incident on the high-reflection area. Furthermore, by making m greater than 0 and less than 0.3, greater than 0.7 and less than 1.3, greater than 1.9 and less than 2.3, or greater than 3.0 and less than 3.3, the deviation of the reflectivity caused by the position of the high-reflection area as described above can also be reduced.

[0165] 1. High reflective layer and protective layer

[0166] Regarding the high reflective layer and the protective layer in the present disclosure, they are the same as those described in the above-mentioned "A. Reflective optical scale for encoder", so the description here is omitted.

[0167] 2. Low reflection layer forming layer

[0168] The layer for forming a low-reflection layer in the present disclosure is a layer before patterning for forming the above-mentioned patterned low-reflection layer, and is preferably provided on the entire surface of the surface of the protective layer opposite to the high-reflection layer side. The layer structure of the layer for forming a low-reflection layer is the same as that of the above-mentioned patterned low-reflection layer, so the description here is omitted.

[0169] C-2. Other forms of laminates for reflective optical scales for encoders

[0170] The present invention also includes other methods of the layered body for a reflective optical scale for an encoder that are different from the layered body for a reflective optical scale for an encoder described in the above-mentioned "C-1. Layered body for a reflective optical scale for an encoder".

[0171] The stacked body for the reflective optical scale for encoder in the present embodiment is a stacked body for the reflective optical scale for encoder used to manufacture the above-mentioned reflective optical scale for encoder, wherein a high-reflection layer and a protective layer are sequentially provided in the thickness direction, and when the film thickness of the above-mentioned protective layer is set to d (μm) and the incident angle of the incident light to the above-mentioned protective layer is set to θ (°), the following formula (1) is satisfied.

[0172] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0173] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0174] The laminate for a reflective optical scale for an encoder of this embodiment is the same as the above-mentioned "C-1. Laminated body for a reflective optical scale for an encoder" except for the layer for forming the low-reflection layer, so the description here is omitted.

[0175] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are illustrative, and structures having substantially the same structure and achieving the same function and effect as the technical concept described in the claims of the present disclosure are all included in the technical scope of the present disclosure.

[0176] Example

[0177] Hereinafter, Experimental Example A, Experimental Example B, Examples, and Comparative Examples are shown to further illustrate the present disclosure.

[0178] (Experimental Example A and Experimental Example B)

[0179] For a laminate having a metal chromium layer (refractive index 3.2) as a high reflective layer and an organic protective layer (refractive index n = 1.58) with a film thickness d (μm) on the high reflective layer as a protective layer, the reflectance (R0, R1, R2, R3) when light with a wavelength λ = 850nm is incident from the protective layer side at an incident angle θ (θ = 0°, 20°, 40°, and 55°) is calculated by simulation. 20 , R 40 , R 55 ).

[0180] At this time, the film thickness d of the protective layer is set to a value obtained by changing m in the following formula (1) with the incident angle θ=0°.

[0181] d=mλ / [2n×cos{Arcsin(sinθ / n)}](1)

[0182] In addition, calculate R0, R 20 , R 40 , R 55 The average value (average reflectivity R ave ), and the difference between the maximum reflectivity and the minimum reflectivity (reflectivity difference ΔR). 20 , R 40 and R 55 The standard reflectance (R′0, R′ 20 , R′ 40 and R′ 55 ), and the average value of the standard reflectivity (average standard reflectivity R′ ave ), the difference between the maximum standard reflectivity and the minimum standard reflectivity (standard reflectivity difference ΔR′). It should be noted that the simulated reflectivity (65.3%) at θ=0° when the above-mentioned protective layer is not provided is the reflectivity of an ideal high-reflectivity layer without any etching residues etc. on the surface of the high-reflectivity layer. The results are shown in Tables 1 to 3. In addition, the film thickness d (μm) of the protective layer and the average reflectivity R ave The relationship curve of (%) is shown in Figure 5 The film thickness d (μm) of the protective layer and the average standard reflectivity R′ are shown. ave The relationship curve of (%) is shown in Figure 6 .

[0183]

[0184]

[0185] [Table 3]

[0186]

[0187] As shown in Tables 1 to 3, when the film thickness d of the protective layer satisfies the above (1) (Experimental Example A), the average standard reflectance R′ ave It is above 72%, confirming that the decrease in reflectivity is suppressed. Furthermore, in Experimental Examples A1 to 9 (0.7≤m≤1.3), the standard reflectivity difference ΔR′ is smaller than that in Experimental Example B2 (m=1.4), confirming that the deviation in reflectivity of light incident on the high-reflection area is suppressed. Similarly, it is confirmed that in Experimental Examples A12 to 16 (1.9≤m≤2.3), the standard reflectivity difference ΔR′ is smaller than that in Experimental Example B4 (m=2.4), Experimental Example B5 (m=2.5), Experimental Example A10 (m=1.7) and Experimental Example A11 (m=1.8). It is confirmed that in Experimental Examples A18 to 20 (3.0≤m≤3.3), the standard reflectivity difference ΔR′ is smaller than that in Experimental Example A17 (m=2.9).

[0188] (Example)

[0189] First, a mirror-finished SUS substrate (thickness 400 μm) was prepared as a high-reflection layer. Next, a protective layer-forming composition containing a phenolphthalein-based (cardo) epoxy resin was applied to the mirror-finished surface of the SUS substrate and cured to form a protective layer with a thickness of 0.27 μm and a refractive index of 1.58. Next, a low-reflection layer having a metal chromium layer, a chromium nitride layer, and a chromium oxide layer in sequence from the protective layer side was formed in a pattern. Thus, an evaluation scale was obtained.

[0190] The surface roughness, glossiness (60° gloss value) and reflectivity of the high-reflection area of ​​the obtained evaluation scale were measured by the following method. In addition, the average value and range of the reflectivity were calculated. The results are shown in Table 4. It should be noted that the film thickness (0.27 μm) of the protective layer is the value of m = 1.0 when the incident angle θ = 0° and the wavelength of the incident light = 0.85 μm in the above (1).

[0191] [Reflectivity]

[0192] The reflectivity was measured using a spectrophotometer "SolidSpec-3700 (trade name)" manufactured by Shimadzu Corporation. At this time, the measurement wavelength was set to 850 nm, (p-polarized light + s-polarized light) / 2, and the incident angle (the angle between the perpendicular line of the surface of the evaluation member and the direction of the incident light) was set to 5° to 70°. In addition, the irradiation beam size was approximately 6 mm × 15 mm.

[0193] [Surface roughness]

[0194] According to JIS B 0601-1994, the arithmetic mean roughness Ra, the maximum height Ry, and the ten-point average roughness Rz were measured.

[0195] [Glossiness]

[0196] The 60° specular glossiness was measured using HANDY GLOSSMETER PG-II (NIPPON DENSHOKU) in accordance with JIS Z8741.

[0197] [Contact angle to water]

[0198] The measurement was carried out in accordance with the provisions of JIS R3257:1999.

[0199] In the case of mirror SUS without a protective layer, it is 31° (Comparative Example 2 in Table 4). When a protective layer of inorganic material is formed on mirror SUS, it is 62°. When a protective layer of organic material is formed on mirror SUS, it is 73° (Example 1 in Table 4) and 75° (Comparative Example 1 in Table 4). The average contact angle of the specified thickness (0.16 μm or more and 1.0 μm or less) is 74.3°.

[0200] (Comparative Example 1)

[0201] The evaluation scale was prepared in the same manner as in Example 1 except that the thickness of the protective layer was 1.0 μm, and the surface roughness, glossiness, and reflectivity of the high reflection region were measured.

[0202] The film thickness (1.0 μm) of the protective layer is a value of m=3.7 when the incident angle θ=0° and the wavelength of the incident light=0.85 μm in the above (1).

[0203] (Comparative Example 2)

[0204] As a high reflective layer, a mirror-finished SUS substrate (thickness 400 μm) was prepared. Next, a metal chromium film was formed without forming a protective layer. Then, etching was performed with acid for 6 minutes to investigate the effect of etching on the surface roughness of the high reflective layer. The surface roughness, glossiness and reflectivity of the high reflective layer after etching were measured. The results are shown in Table 4.

[0205] (Reference Example 1 to Reference Example 4)

[0206] The high reflective layer (mirror-finished SUS substrate) was etched with acid for the time shown in Table 4, and the surface roughness, glossiness, and reflectivity of the high reflective layer after etching were measured.

[0207]

[0208] According to the results in Table 4, it was confirmed that Example 1 obtained a higher reflectivity than Comparative Examples 1 and 2. In Comparative Example 2, metal chromium residue was confirmed after etching of the metal chromium film, and it is presumed that the reflectivity decreased due to the influence of the etching residue. It should be noted that the residue did not disappear even if the etching time was extended.

[0209] It should be noted that in the above-mentioned reflectivity measurement, the irradiation beam size is relatively large, about 6mm×15mm, but the size of the actual light receiving portion (high reflection area) of the encoder is, for example, less than 100μm, usually as small as about 50μm. In the case where the surface roughness of the high reflection layer is rough as in Comparative Example 2, it is assumed that the smaller the beam size, the worse the reflectivity, so it is presumed that the reflectivity increase effect brought about by the present disclosure is actually more significantly obtained.

[0210] [Evaluation of angular dependence of reflectivity]

[0211] For the high reflection area of ​​the evaluation scale of the above-mentioned Example, Comparative Example 1, Comparative Example 2 and Reference Example 1, the wavelength of the measurement light was changed from 400nm to 900nm, and the incident angle was changed from 5° to 70°, and the reflectivity was measured. The results are shown in FIG. 7(a) (Example), Figure 7 (b) (Reference Example 1), Figure 8 (a) (Comparative Example 1), Figure 8 (b) (Comparative Example 2).

[0212] like Figure 7 As shown in (a), the high reflection area in the evaluation scale of the embodiment has the same degree of reflectivity and incident angle dependence as that of Reference Example 1 (mirror-finished SUS substrate). Figure 8 As shown in (a), it was confirmed that if the film thickness of the protective layer is not controlled, the incident angle dependence of the reflectivity becomes larger due to thin film interference. Figure 8 As shown in (b), it was confirmed that the reflectivity of the high reflection region decreased when the protective layer was not provided. It is presumed that this is because the surface roughness of the high reflection layer after etching is large.

[0213] That is, the present disclosure can provide the following inventions.

[0214] [1] A reflective optical scale for an encoder, wherein a high-reflection layer, a protective layer, and a low-reflection layer arranged in a pattern are provided in sequence in a thickness direction, the reflective optical scale for an encoder having a low-reflection region as a region where the low-reflection layer is provided and a high-reflection region as a region where the protective layer is exposed,

[0215] When the film thickness of the protective layer is d (μm) and the incident angle of the incident light on the protective layer is θ (°), the following formula (1) is satisfied.

[0216] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0217] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0218] [2] A reflective optical scale for an encoder as described in [1], wherein m is in the range of greater than 0 and less than 0.3, greater than 0.7 and less than 1.3, greater than 1.9 and less than 2.3, or greater than 3.0 and less than 3.3.

[0219] [3] A reflective optical scale for an encoder as described in [1] or [2], wherein the protective layer contains an organic material.

[0220] [4] A reflective optical scale for an encoder as described in any one of [1] to [3], wherein the high reflective layer is a metal substrate.

[0221] [5] A reflective optical scale for an encoder as described in any one of [1] to [4], wherein the low-reflection layer has a metal chromium film, and a chromium oxide film and a chromium nitride film arranged in different orders from the side of the protective layer.

[0222] [6]. A reflective optical encoder, characterized in that it comprises: a reflective optical scale for an encoder as described in any one of claims [1] to [5]; a light source for irradiating the measuring light onto the surface of the reflective optical scale for an encoder on the side where the low-reflective layer is arranged; and a light detector for detecting the reflected light from the reflective optical scale for an encoder.

[0223] [7] A laminate for a reflective optical scale for an encoder, which is used to manufacture the reflective optical scale for an encoder described in any one of [1] to [5], wherein the laminate has a high reflection layer, a protective layer and a layer for forming a low reflection layer in the thickness direction,

[0224] When the film thickness of the protective layer is d (μm) and the incident angle of the incident light on the protective layer is θ (°), the following formula (1) is satisfied.

[0225] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0226] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0227] [8] A reflective optical scale for an encoder, which has a high reflective layer, a protective layer comprising an organic material, and a low reflective layer arranged in a pattern in sequence in the thickness direction, and has: a low reflective region, which is a region where the high reflective layer, the protective layer, and the low reflective layer are arranged; and a high reflective region, which is a region where the high reflective layer and the protective layer are arranged, wherein the thickness of the protective layer is greater than 0.16 μm and less than 1.0 μm, and the reflectivity at the high reflective region is greater than 40% when the wavelength of the measuring light source is set to 850 μm.

[0228] [9] A reflective optical scale for an encoder, which has a high reflective layer, a protective layer containing an organic material, and a low reflective layer arranged in a pattern in sequence in the thickness direction, and has: a low reflective region, which is a region where the high reflective layer, the protective layer, and the low reflective layer are arranged; and a high reflective region, which is a region where the high reflective layer and the protective layer are arranged, and the reflectivity in the low reflective region is less than 2% when the wavelength of the measuring light source is set to 850 μm, and the S / N ratio represented by the following formula is greater than 30.

[0229] S / N ratio = reflectivity of high reflection area / reflectivity of low reflection area.

[0230]

[10] A reflective optical scale for an encoder as described in [9], wherein:

[0231] The protective layer has a thickness of 0.16 μm or more and 1.0 μm or less.

[0232] When the wavelength of the measurement light source is 850 μm, the reflectance in the high reflection region is 40% or more.

[0233]

[11] A reflective optical scale for an encoder as described in any one of [1] to [5] or any one of [8] to

[10] , wherein the contact angle of the protective layer to water is greater than 50° and less than 90°.

[0234]

[12] A laminate for a reflective optical scale for an encoder, which is used to manufacture a reflective optical scale for an encoder as described in any one of [1] to [5] or any one of [8] to

[11] , wherein:

[0235] The laminate has a high reflection layer and a protective layer in this order in the thickness direction.

[0236] When the film thickness of the protective layer is d (μm) and the incident angle of the incident light on the protective layer is θ (°), the following formula (1) is satisfied.

[0237] d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1)

[0238] (where n is the refractive index of the protective layer, λ is the wavelength of the incident light (μm), and m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3 (p is an integer greater than or equal to 1 and less than or equal to 3).)

[0239] Description of Reference Numerals

[0240] 1…Highly reflective layer

[0241] 2…Protective layer

[0242] 3…Low reflective layer

[0243] 3a…Chromium oxide film

[0244] 3b…Chromium nitride film

[0245] 3c…Metallic chromium film

[0246] 10…Reflective optical scale for encoder

[0247] 50…Laminate for reflective optical scale for encoder

[0248] 100…Reflective optical encoder

Claims

1. A reflective optical scale for an encoder, wherein: In the thickness direction, a high reflection layer, a protective layer and a low reflection layer arranged in a pattern are sequentially provided. The reflective optical scale for the encoder has a low-reflection area as an area where the low-reflection layer is provided and a high-reflection area as an area where the protective layer is exposed. When the film thickness of the protective layer is d, the unit is μm, and the incident angle of the incident light to the protective layer is θ, the following formula (1) is satisfied: d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1) In the formula, n is the refractive index of the protective layer, λ is the wavelength of the incident light, in μm, m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3, and p is an integer greater than or equal to 1 and less than or equal to 3.

2. The reflective optical scale for an encoder according to claim 1, wherein: The m is in the range of greater than 0 and less than 0.3, greater than 0.7 and less than 1.3, greater than 1.9 and less than 2.3, or greater than 3.0 and less than 3.

3.

3. The reflective optical scale for an encoder according to claim 1, wherein: The protective layer includes an organic material.

4. The reflective optical scale for an encoder according to claim 1, wherein: The high reflection layer is a metal substrate.

5. The reflective optical scale for an encoder according to claim 1, wherein: The low reflection layer includes a metal chromium film, and a chromium oxide film and a chromium nitride film arranged in different orders from the protective layer side.

6. A reflective optical encoder, characterized in that: have: A reflective optical scale for an encoder as claimed in any one of claims 1 to 5; A light source for irradiating measuring light onto the surface of the encoder reflective optical scale on the side where the low-reflection layer is arranged; as well as A light detector detects reflected light from the reflective optical scale used for the encoder.

7. A reflective optical scale laminate for an encoder, which is used to manufacture the reflective optical scale for an encoder as claimed in any one of claims 1 to 5, wherein: The laminate has a high reflection layer, a protective layer, and a layer for forming a low reflection layer in this order in the thickness direction. When the film thickness of the protective layer is d, the unit is μm, and the incident angle of the incident light to the protective layer is θ, the following formula (1) is satisfied: d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1) In the formula, n is the refractive index of the protective layer, λ is the wavelength of the incident light, in μm, m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3, and p is an integer greater than or equal to 1 and less than or equal to 3.

8. A reflective optical scale for an encoder, wherein: In the thickness direction, a high reflection layer, a protective layer containing an organic material, and a low reflection layer arranged in a pattern are sequentially provided. It has: a low reflection region, which is a region where the high reflection layer, the protective layer and the low reflection layer are provided; and a high reflection region, which is a region where the high reflection layer and the protective layer are provided. The protective layer has a thickness of 0.16 μm or more and 1.0 μm or less. When the wavelength of the measurement light source is 850 μm, the reflectivity in the high reflection region is 40% or more.

9. A reflective optical scale for an encoder, wherein: In the thickness direction, a high reflection layer, a protective layer containing an organic material, and a low reflection layer arranged in a pattern are sequentially provided. It has: a low reflection region, which is a region where the high reflection layer, the protective layer and the low reflection layer are provided; and a high reflection region, which is a region where the high reflection layer and the protective layer are provided. When the wavelength of the measurement light source is 850 μm, the reflectivity in the low reflection region is 2% or less. The S / N ratio represented by the following formula is 30 or more, S / N ratio = reflectivity of high reflection area / reflectivity of low reflection area.

10. The reflective optical scale for an encoder according to claim 9, wherein: The protective layer has a thickness of 0.16 μm or more and 1.0 μm or less. When the wavelength of the measurement light source is 850 μm, the reflectivity in the high reflection region is 40% or more.

11. A reflective optical scale for an encoder as claimed in any one of claims 1 to 5 or any one of claims 8 to 10, wherein: The contact angle of the protective layer to water is greater than or equal to 50° and less than or equal to 90°.

12. A reflective optical scale laminate for an encoder, which is used to manufacture a reflective optical scale for an encoder as claimed in any one of claims 1 to 5 or any one of claims 8 to 11, wherein: The laminate has a high reflection layer and a protective layer in this order in the thickness direction. When the film thickness of the protective layer is d, the unit is μm, and the incident angle of the incident light to the protective layer is θ, the following formula (1) is satisfied: d=mλ / [2n×cos{Arcsin(sinθ / n)}] (1) In the formula, n is the refractive index of the protective layer, λ is the wavelength of the incident light, in μm, m is a number satisfying 0<m≤0.3 or p-0.3≤m≤p+0.3, and p is an integer greater than or equal to 1 and less than or equal to 3.

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