JP2013117512A - Reflector plate to be used for optical encoder and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflector plate which is excellent in durability, and which is inexpensively manufacturable, and which can be made thinner in thickness.SOLUTION: Disclosed is a reflector plate to be used for an optical encoder comprising a metal plate 10 with a single-layer structure having a face 11 to which mirror surface processing has been applied and a plurality of recesses 12 having a bottom face 13 whose optical reflectance is lower than that of the face 11 on at least one face Fside.

Description

  The present invention relates to a reflector used in an optical encoder and a method for manufacturing the same.

  A conventional reflector has a multilayer structure in which a film for forming a reflection pattern on a substrate, a film for protecting the film, and the like are laminated.

  However, the reflective plate having a multilayer structure has a problem that the film on the substrate is easily peeled off due to a change in temperature and humidity, adhesion of chemicals, etc. due to impact resistance. In addition, since it has a multi-layer structure, there are many manufacturing processes, and it takes time to manufacture and the cost is high. Furthermore, since it is manufactured by laminating a plurality of films on a substrate, there is a drawback that it is difficult to reduce the thickness.

Japanese Patent Laid-Open No. 5-99695 JP-A-6-94401 Japanese Patent Laid-Open No. 10-82661 JP 2005-241248 A

  The problem to be solved by the present invention is to provide a reflector that is excellent in durability, can be manufactured at low cost, and can be made thinner.

In order to solve the above-described problems, the present invention provides the following reflector and a manufacturing method thereof.
1. A metal plate having a single-layer structure, which is used in an optical encoder and includes a mirror-finished surface and a plurality of concave portions having a bottom surface having a lower light reflectance than the surface. A reflector made of
2. 2. A reflection plate in which a layer having a surface lower than the light reflectance of the bottom surface is provided on the bottom surface of the concave portion of the reflection plate according to 1 above.
3. A method of manufacturing a reflector used in an optical encoder, comprising a step of applying a mirror finish to a surface of at least one surface of a metal plate having a single-layer structure, and reflecting the surface of the mirror-finished surface more than the surface. Forming a recess having a bottom surface with a low rate.
4). 4. The method according to 3 above, wherein the recess is formed by etching so that fine irregularities are formed on the bottom surface of the recess.
5. 4. The method according to 3 above, wherein the recess is formed by sandblasting so that fine irregularities are formed on the bottom surface of the recess.
6). 4. The method according to 3 above, comprising a step of providing a layer having a surface lower than the light reflectance of the bottom surface on the bottom surface of the recess.

The reflecting plate of the present invention is composed of a metal plate having a single-layer structure provided with a mirror-finished surface and a plurality of concave portions having a bottom surface having a light reflectance lower than that of the surface. In addition, there is no problem that the film laminated on the base material is peeled off due to a change in temperature and humidity or chemical adhesion as in the prior art. Further, since it is made of a single-layered metal plate, there is an advantage that it is less susceptible to adverse effects such as distortion due to changes in temperature and humidity or adhesion of chemicals. Moreover, since it consists of a metal plate having a single-layer structure, the number of manufacturing steps is small, and it is possible to manufacture at low cost and in a short time. Furthermore, since it has a single-layer structure, the thickness can be reduced.
According to the method for manufacturing a reflector of the present invention, it is possible to provide a reflector having the above-described effects.

FIG. 1 is a plan view showing a reflector according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 5 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 7 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 8 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 9 is a diagram for explaining the manufacturing method of the reflector according to the first embodiment of the present invention. FIG. 10 is an enlarged cross-sectional view of the concave portion of the reflector according to the first embodiment of the present invention. FIG. 11 is an enlarged cross-sectional view of the concave portion of the reflector according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the technical scope of the present invention is not limited to the contents of the following description. In addition, this invention is applicable not only to the reflecting plate used for a rotary encoder but to the reflecting plate used for a linear encoder etc.

FIG. 1 is a plan view of a reflector according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in these figures, the reflection plate according to the present embodiment, the surface (surface) located to one surface F ₁ on 2, other surface F faces (back surface) located under the drawing ₂ , a single-layer structure having a mirror-finished surface 11 and a plurality of concave portions 12 radially formed at predetermined intervals along a circular edge on at least one surface F ₁ side. It consists of a metal plate 10.

  The metal plate 10 employed in the present embodiment is a single plate made of stainless steel, but the metal plate 10 is not limited to a stainless steel plate, and the material constituting the metal plate can be arbitrarily selected. The single layer structure means a structure composed of a single layer in which nothing is laminated. Therefore, the “single-layer metal plate” means a metal plate made of an arbitrarily selected material and not having a multilayer structure.

  The recess 12 has a bottom surface 13 having a light reflectance lower than that of the surface 11 subjected to mirror finishing. More specifically, as shown in FIG. 10, fine irregularities are formed on the bottom surface 13 of the recess 12, and light is irregularly reflected by the irregularities, so the light reflectance of the bottom surface 13 is a mirror surface. The light reflectance is lower than 11.

  The reflection plate configured as described above is used as a member that reflects light emitted from a light emitting element in an optical encoder including a light emitting element and a light receiving element. Then, the light reflected by the reflecting plate enters the light receiving element. The reflection plate can change the intensity of the reflected light depending on the portion irradiated with light. That is, the case where the light emitted from the light emitting element is applied to the mirror surface 11 (the surface existing between the recesses 12) and the case where the light is applied to the bottom surface 13 of the recess 12 are compared. Then, since the bottom surface 13 of the recessed part 12 is lower than the surface 11 which is a mirror surface, the former emits reflected light stronger than the latter. For this reason, the optical encoder provided with this reflecting plate can detect the position, speed, etc. of the object by detecting light with the light receiving element.

Incidentally, depending on the mode of use, to the other surface F ₂ side, similarly to the one surface F ₁ side, a surface on which mirror finishing has been performed, and a plurality of recesses having a bottom surface reflectivity is lower than said surface It is also possible to provide a reflecting plate made of a single-layer metal plate.

  Next, an example of the manufacturing method of the reflector which concerns on a present Example is demonstrated.

The reflecting plate according to the present example has a step of applying a mirror finish to the surface of the metal plate having the single-layer structure on the one side F ₁ side, and the surface 11 subjected to the mirror finish has a light reflectance lower than that of the surface 11. And a step of forming the recess 12 having the bottom surface 13.

Specifically, first, as shown in FIG. 3, the surface of one metal plate 10 is mirror-finished using a method such as lapping or buffing, and the surface of the metal plate 10 is moved to the first surface F ₁ side. Create a glossy surface with no irregularities. Next, as shown in FIG. 4, a photoresist 20 is applied on the surface 11 that has been subjected to mirror finishing. Next, as shown in FIG. 5, exposure is performed using a photomask 21, and the pattern of the photomask 21 is transferred to the photoresist 20. Next, as shown in FIG. 6, the photoresist other than the pattern portion is removed using a developer. Next, as shown in FIG. 7, the etching solution 23 is sprayed from above, and as shown in FIG. 8, the recess 12 is formed in the metal plate 10 where the photoresist 20 has been removed. By this etching process, fine irregularities are formed on the bottom surface 13 of the recess 12 (see FIG. 10). Thereby, the recessed part 12 which has the bottom face 13 whose light reflectivity is lower than the surface 11 to which the mirror finishing was performed is formed. Finally, as shown in FIG. 9, the photoresist 20 in the pattern portion remaining on the metal plate 10 is removed.

According to the manufacturing method described above, with directly subjected to mirror finish on one surface F ₁ side of the metal plate 10 of a single-layer structure, to form a recess 12, the reflectance of the light produces a higher portion and a lower portion, prepared The number of processes is small, and the reflector can be manufactured at low cost and in a short time. In addition, the thickness of the entire reflector can be made thinner than that of a reflector having a multilayer structure.

  In addition, the reflector manufactured by the above-described manufacturing method is resistant to impact, and there is no problem that the film laminated on the base material is peeled off due to a change in temperature and humidity or chemical adhesion as in the prior art. Moreover, since it consists of the metal plate 10 of single layer structure, there exists an advantage that it is hard to receive the bad influences, such as distortion by a change of temperature or humidity, or chemical adhesion.

In addition to the above-described manufacturing method, the mirror-finished surface 11 can be covered with a transparent protective film (not shown). As the protective film, for example, a silicon dioxide (SiO ₂ ) film or the like can be employed. By adopting a two-layer structure of the metal plate 10 having a single-layer structure and a transparent protective film, the surface 11 having a high light reflectance can be protected from dirt and scratches.

  In the manufacturing method described above, the recess 12 is formed by etching, but the recess 12 may be formed by sandblasting instead of etching. Even when abrasive particles are sprayed onto the metal plate 10 to form the recesses 12, fine irregularities are formed on the bottom surface 13 of the recesses 12, so that the same recesses 12 can be formed by sandblasting as in the etching process.

  FIG. 11 is an enlarged cross-sectional view of the concave portion of the reflector according to the second embodiment of the present invention. As shown in this figure, the reflector according to the present embodiment is the reflector according to the first embodiment in that a layer 30 having a surface lower than the light reflectivity of the bottom surface is provided on the bottom surface of the recess. And different.

  As described above, the bottom surface 13 of the recess 12 has a light reflectance lower than that of the surface 11 that has been mirror-finished. However, a highly accurate light-receiving element may mistakenly detect a part of light irregularly reflected by the fine unevenness of the bottom surface 13 as light reflected on the mirror-finished surface 11. In order to prevent this, in this embodiment, the layer 30 is provided on the bottom surface of the recess.

  The layer 30 can be formed by plating or painting. In this embodiment, the layer 30 is formed by black chrome plating. Specifically, the recess 12 is formed in one metal plate 10. The steps until the recess 12 is formed are the same as those in the first embodiment. Next, black chrome is plated so as to cover the bottom surface 13 of the recess 12. Finally, the photoresist on the pattern portion remaining on the metal plate 10 is removed.

  According to this manufacturing method, as shown in FIG. 11, not only the bottom surface 13 of the recess 12 but also the side surface 14 of the recess 12 is plated with black chrome, so that mirror finishing was performed. A significant difference can be made between the intensity of the light reflected on the surface 11 and the intensity of the light reflected on the recess 12. Therefore, even with a high-precision light receiving element, it is possible to accurately distinguish and detect light reflected on the mirror-finished surface 11 and light reflected on the recess 12.

  In the reflecting plate according to the present embodiment, the layer 30 having a surface lower than the light reflectance of the bottom surface is provided on the bottom surface of the concave portion. It becomes possible to accurately detect the speed and the like.

DESCRIPTION OF SYMBOLS 10 Metal plate 11 Mirror-finished surface 12 Concavity 13 Bottom surface of concavity 20 Photoresist 21 Photomask 22 Light 23 Etching solution 30 layer

Claims (6)

  A metal plate having a single-layer structure, which is used in an optical encoder and includes a mirror-finished surface and a plurality of concave portions having a bottom surface having a lower light reflectance than the surface. A reflector made of   A reflecting plate in which a layer having a surface lower than the light reflectance of the bottom surface is provided on the bottom surface of the concave portion of the reflecting plate according to claim 1.   A method of manufacturing a reflector used in an optical encoder, comprising a step of applying a mirror finish to a surface of at least one surface of a metal plate having a single-layer structure, and reflecting the surface of the mirror-finished surface more than the surface. Forming a recess having a bottom surface with a low rate.   The method according to claim 3, wherein the recess is formed by etching so that fine irregularities are formed on a bottom surface of the recess.   The method according to claim 3, wherein the concave portion is formed by sandblasting so that fine irregularities are formed on a bottom surface of the concave portion.   The method according to claim 3, further comprising providing a layer having a surface lower than the light reflectance of the bottom surface on the bottom surface of the recess.

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