Optical module for encoder, encoder, and method of manufacturing optical module for encoder

Abstract

This optical module comprises: a support having a bottom wall, a light receiving element disposed on the surface of the bottom wall with the light receiving surface facing away from the bottom wall; an FOP having an input surface composed of one end surface of each of a plurality of optical fibers and an output surface composed of the other end surface of each of the plurality of optical fibers, the FOP being disposed on the light receiving element with the output surface facing the light receiving surface; a first resin member disposed between the light receiving surface and the output surface, and bonding the FOP to the light receiving element; and a second resin member disposed on the surface of the bottom wall so as to be in contact with the light receiving element and the FOP. The material of the first resin member and the material of the second resin member are different from each other.

Description

Optical module for encoder, encoder, and method for manufacturing optical module for encoder

[0001] One aspect of the present disclosure relates to an optical module for an encoder, an encoder, and a method for manufacturing the optical module for an encoder.

[0002] Patent Document 1 describes an optical encoder in which a fiber optic plate is disposed on a light receiving element, and light emitted from a light emitting element and reflected by a rotating plate passes through the fiber optic plate and enters the light receiving element.

[0003] Japanese Patent Application Laid-Open No. 2019-211360

[0004] Encoders such as those described above may be required to have various performance characteristics, such as improved detection accuracy or stable placement of the fiber optic plate on the light-receiving element, and it is necessary to realize a design that meets the required performance.

[0005] An object of one aspect of the present disclosure is to provide an optical module for an encoder, an encoder, and a method for manufacturing such an optical module for an encoder that can be designed according to required performance.

[0006] An optical module for an encoder according to one aspect of the present disclosure comprises a support body having a bottom wall portion, a light-receiving element having a light-receiving surface and arranged on the surface of the bottom wall portion so that the light-receiving surface faces away from the bottom wall portion, a fiber optic plate having an input surface formed by one end faces of a plurality of optical fibers and an output surface formed by the other end faces of the plurality of optical fibers and arranged on the light-receiving element so that the output surface faces the light-receiving surface, a first resin member arranged between the light-receiving surface and the output surface and joining the fiber optic plate to the light-receiving element, and a second resin member arranged on the surface of the bottom wall portion so as to contact the light-receiving element and the fiber optic plate, wherein the materials of the first resin member and the second resin member are different from each other.

[0007] This optical module for an encoder includes a first resin member disposed between the light receiving surface of the light receiving element and the output surface of the fiber optic plate, bonding the fiber optic plate to the light receiving element, and a second resin member disposed on the surface of the bottom wall portion so as to contact the light receiving element and the fiber optic plate. This allows the first resin member to firmly bond the fiber optic plate to the light receiving element, while the second resin member reliably supports the fiber optic plate and the light receiving element. Furthermore, the materials of the first resin member and the second resin member are different from each other. This allows for greater freedom in selecting materials for the first and second resin members, thereby enabling designs tailored to required performance. For example, the first resin member can be formed of a material with high optical transmittance, and the second resin member can be formed of a material with low optical transmittance. In this case, light traveling from the fiber optic plate toward the light receiving element is prevented from being blocked by the first resin member, while noise light traveling toward the light receiving element from the side can be blocked by the second resin member. As a result, detection accuracy can be improved. As another example, the first resin member can be formed of a soft material and the second resin member can be formed of a hard material. In this case, the fiber optic plate and the light receiving element can be more reliably supported by the second resin member while preventing separation between the fiber optic plate and the light receiving element bonded by the first resin member. As a result, the fiber optic plate can be stably positioned on the light receiving element. In this way, this optical module for encoders can be designed to meet required performance requirements.

[0008] The optical module for an encoder may further include a wire connected to the bottom wall and the light receiving element, and the second resin member may cover the wire, thereby protecting the wire from oil that may be scattered when the encoder is in use, physical external forces, and the like.

[0009] The peripheral edge of the surface of the bottom wall portion may be exposed from the second resin member. That is, the second resin member may be formed so as not to reach the peripheral edge (outer edge) of the surface of the bottom wall portion. When manufacturing the optical module for encoder, the second resin member may be disposed on the surface of the bottom wall portion before hardening. However, if the second resin member is formed so as not to reach the peripheral edge of the surface of the bottom wall portion, there is no need to dispose a structure (e.g., a side wall portion) on the bottom wall portion to block the second resin member before hardening. This allows for the miniaturization of the optical module for encoder.

[0010] The support body may further include a sidewall portion disposed on the surface of the bottom wall portion, and the sidewall portion may surround the light-receiving element and the second resin member when viewed from the thickness direction of the bottom wall portion, and the second resin member may be in contact with the sidewall portion. In this case, the sidewall portion can block the uncured second resin member during manufacturing of the optical module for an encoder. Therefore, a low-viscosity material can be used as the material for the second resin member. Furthermore, the sidewall portion can protect the light-receiving element from physical contact.

[0011] The first resin member may be an adhesive film. In this case, the heated first resin member hardens in a relatively short time, so that the first resin member can bond the fiber optic plate to the light receiving element with high precision.

[0012] The first resin member may be a die attach film. In this case, the heated first resin member hardens in a relatively short time, so that the fiber optic plate can be joined to the light receiving element with high precision by the first resin member.

[0013] When viewed from the thickness direction of the bottom wall portion, the outer edge of the first resin member may overlap the outer edge of the fiber optic plate. In this case, the first resin member does not protrude outside the fiber optic plate when viewed from the thickness direction of the bottom wall portion, thereby reducing the contact area between the first resin member and the second resin member. Therefore, when the first resin member and the second resin member thermally contract or expand due to a change in environmental temperature, damage to the contact points between the first resin member and the second resin member can be suppressed.

[0014] The light transmittance of the second resin member may be lower than that of the first resin member. In this case, the light from the fiber optic plate toward the light receiving element can be prevented from being blocked by the first resin member, while noise light traveling toward the light receiving element from the side can be blocked by the second resin member. As a result, detection accuracy can be improved.

[0015] The second resin member is harder than the first resin member. In this case, the fiber optic plate and the light receiving element can be more reliably supported by the second resin member while preventing separation between the fiber optic plate and the light receiving element bonded by the first resin member. As a result, the fiber optic plate can be stably positioned on the light receiving element.

[0016] The optical module for an encoder may further include an anti-reflection layer formed on the input surface of the fiber optic plate, which can suppress reflection of light at the input surface of the fiber optic plate and improve detection accuracy.

[0017] The fiber optic plate may have a pair of side surfaces facing opposite each other in a direction perpendicular to the thickness direction of the bottom wall portion, and the second resin member may be in contact with both of the pair of side surfaces. In this case, the light receiving element and the fiber optic plate can be more reliably supported by the second resin member.

[0018] An encoder according to one aspect of the present disclosure includes a rotating plate having a light transmitting pattern or a light reflecting pattern, and the above-mentioned encoder optical module arranged so that light passing through the light transmitting pattern or light reflected by the light reflecting pattern is incident on a light receiving element. For the reasons described above, this encoder makes it possible to realize a design that meets required performance.

[0019] A manufacturing method of an optical module for an encoder according to one aspect of the present disclosure is a manufacturing method of an optical module for an encoder comprising: a support having a bottom wall portion; a light-receiving element having a light-receiving surface; a fiber optic plate having an input surface formed by one end faces of a plurality of optical fibers and an output surface formed by the other end faces of the plurality of optical fibers; a first resin member for joining the fiber optic plate to the light-receiving element; and a second resin member arranged on the surface of the bottom wall portion, the method comprising, in this order: a first step of arranging the light-receiving element on the surface of the bottom wall portion so that the light-receiving surface faces away from the bottom wall portion; a second step of arranging the fiber optic plate on the light-receiving element so that the output surface faces the light-receiving surface and joining the fiber optic plate to the light-receiving element with the first resin member arranged between the light-receiving surface and the output surface; and a third step of arranging the second resin member on the surface of the bottom wall portion so that it contacts the light-receiving element and the fiber optic plate, wherein the materials of the first resin member and the second resin member are different from each other.

[0020] This method for manufacturing an optical module for an encoder includes a second step of placing a fiber optic plate on a light-receiving element so that its output surface faces the light-receiving surface of the light-receiving element, and bonding the fiber optic plate to the light-receiving element with a first resin member disposed between the light-receiving surface and the output surface; and a third step of placing a second resin member on the surface of the bottom wall portion so that it contacts the light-receiving element, the first resin member, and the fiber optic plate. This allows the first resin member to firmly bond the fiber optic plate to the light-receiving element, and the second resin member to reliably support the fiber optic plate and the light-receiving element. Furthermore, the first resin member and the second resin member are made of different materials. As described above, this allows for greater flexibility in selecting the materials for the first and second resin members, thereby enabling designs that meet required performance to be realized. Furthermore, in this method of manufacturing an optical module for an encoder, after the second step of joining the fiber optic plate to the light-receiving element with the first resin member, a third step of arranging the second resin member on the surface of the bottom wall portion so as to contact the light-receiving element, the first resin member, and the fiber optic plate is performed. This makes it possible to prevent the position of the fiber optic plate relative to the light-receiving element from shifting during manufacturing, and to prevent a decrease in yield.

[0021] The first resin member may be an adhesive film. In this case, the heated first resin member hardens in a relatively short time, so that the first resin member can bond the fiber optic plate to the light receiving element with high precision.

[0022] The first resin member may be a die attach film. In this case, the heated first resin member hardens in a relatively short time, so that the fiber optic plate can be joined to the light receiving element with high precision by the first resin member.

[0023] In the second step, the first resin member is cured to bond the fiber optic plate to the light-receiving element. In the third step, the second resin member is placed on the surface of the bottom wall portion and then cured. The viscosity of the first resin member before curing in the second step may be lower than the viscosity of the second resin member before curing in the third step. In this case, the low viscosity of the first resin member before curing can prevent air bubbles from forming in the first resin member after curing, allowing the fiber optic plate to be stably positioned on the light-receiving element. Furthermore, the high viscosity of the second resin member before curing can eliminate a structure (e.g., a side wall portion) for blocking the second resin member, improving manufacturing efficiency.

[0024] The manufacturing method of the optical module for an encoder may further include a forming step of forming a fiber optic plate before the second step, and the forming step may include, in this order, a step of attaching a second base material having a plurality of portions corresponding to the first resin member to a first base material having a plurality of portions corresponding to the fiber optic plate, and a step of cutting the first base material and the second base material to obtain a plurality of fiber optic plates to which the first resin member is attached. In this case, manufacturing efficiency can be improved compared to, for example, a case in which the first resin member is attached individually to a plurality of fiber optic plates.

[0025] The method for manufacturing an optical module for an encoder may further include a fourth step of cutting the third substrate to obtain a plurality of optical modules for an encoder, the fourth step being for obtaining ... fifth step being for obtaining a plurality of optical modules for an encoder, the fourth step being for obtaining a plurality of optical modules for an encoder, the fifth step being for obtaining a plurality of optical modules for an encoder, the fifth step being for obtaining a plurality of optical modules for an encoder, the fifth step being for obtaining a plurality of optical modules for an encoder, the fifth step being for obtaining a plurality of optical modules for an encoder

[0026] In the third step, the second resin member may be disposed on the surface of the bottom wall portion so as to be spaced apart from the boundaries between the plurality of bottom wall portions, which eliminates the need to provide a structure (e.g., a side wall portion) on the boundaries to block the uncured second resin member, thereby improving manufacturing efficiency.

[0027] According to one aspect of the present disclosure, it is possible to provide an optical module for an encoder, an encoder, and a method for manufacturing such an optical module for an encoder that can be designed according to required performance.

[0028] Fig. 2 is a perspective view of an encoder according to an embodiment; Fig. 3 is a cross-sectional view of the optical module shown in Fig. 1; Figs. 3(a) and 3(b) are views showing a method for manufacturing the optical module ... cross-sectional views of an optical module according to a modified example;

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and duplicated descriptions will be omitted. [Encoder Configuration]

[0030] 1, the encoder 1 includes a rotating shaft 2, a rotating plate 3, a fixed plate 4, a light source 5, an optical module (encoder optical module) 6, and a processing unit 7. The rotating shaft 2 rotates about an axis A. The encoder 1 is, for example, an absolute rotary encoder, and is a device for detecting the absolute angle of a measurement object connected to the rotating shaft 2. In this embodiment, the encoder 1 is a transmission type encoder.

[0031] The rotating plate 3 is fixed to the rotating shaft 2 and rotates together with the rotating shaft 2. The rotating plate 3 is a so-called code wheel. The rotating plate 3 is formed in a disk shape and is attached to the rotating shaft 2 at its center so as to be disposed perpendicular to the axis A. The rotating plate 3 has a light transmission pattern 3a through which light emitted from the light source 5 passes. The light transmission pattern 3a represents a predetermined pattern such as a gray code. The light transmission pattern 3a is composed of a plurality of slits that penetrate the rotating plate 3. The insides of these slits may be empty, or a transparent glass portion may be disposed within the slits.

[0032] The fixed plate 4 is fixed at a position facing the rotating plate 3. The fixed plate 4 is formed, for example, in the shape of a rectangular plate and is arranged parallel to the rotating plate 3. The fixed plate 4 has a light-transmitting pattern 4a formed so as to be located on a straight line connecting the light source 5 and the optical module 6. The light-transmitting pattern 4a is composed of a plurality of slits penetrating the fixed plate 4. The inside of these slits may be an air gap, or a transparent glass portion may be arranged in the slit. The light source 5 is a light-emitting element such as an LED (Light Emitting Diode). The light source 5 is arranged on the opposite side of the rotating plate 3 from the optical module 6, and emits light toward the rotating plate 3.

[0033] The optical module 6 is an encoder optical module that is applied to the encoder 1, and is fixed at a position opposite the light source 5 with respect to the rotating plate 3 and the fixed plate 4. The optical module 6 has a light receiving element 12, which will be described later, and detects light from the light source 5 by the light receiving element 12. The processing unit 7 is, for example, a signal processing circuit, and encodes the light detection result of the light receiving element 12 of the optical module 6 to output a Gray code that represents the absolute value of the rotation angle of the rotating shaft 2.

[0034] In the encoder 1, when the light transmitting pattern 3a of the rotating plate 3 and the light transmitting pattern 4a of the fixed plate 4 overlap on the line connecting the light source 5 and the light receiving element 12 of the optical module 6, the light from the light source 5 passes through the rotating plate 3 and the fixed plate 4 and enters the light receiving element 12. On the other hand, when the light transmitting pattern 3a and the light transmitting pattern 4a do not overlap, the light from the light source 5 is blocked by the rotating plate 3 and does not enter the light receiving element 12. [Configuration of the optical module]

[0035] As shown in FIG. 2, the optical module 6 includes a support 11, a light receiving element 12, a fiber optic plate 13, a first resin member 14, an anti-reflection layer 15, a wire 16, and a second resin member 17.

[0036] In this example, the support 11 is a substrate member consisting only of a bottom wall portion 18. The bottom wall portion 18 is rectangular plate-shaped and has a flat surface 18a. The bottom wall portion 18 may be formed of, for example, glass epoxy resin. The bottom wall portion 18 has wiring (not shown) to which the wires 16 are connected. Hereinafter, the thickness direction of the bottom wall portion 18 (the direction perpendicular to the surface 18a) is referred to as direction D1, and the direction perpendicular to direction D1 is referred to as direction D2.

[0037] The light-receiving element 12 is a rectangular plate-shaped light-receiving chip that detects light that has passed through the light-transmitting pattern 3a. The light-receiving element 12 has a light-receiving portion 121. The light-receiving portion 121 is, for example, a photodiode or a photodiode array, and has a light-receiving surface 121a on the upper surface 12a of the light-receiving element 12. The light-receiving surface 121a is located in the center of the upper surface 12a and constitutes part of the upper surface 12a. The light-receiving element 12 is disposed on the surface 18a of the bottom wall 18 so that the light-receiving surface 121a faces away from the bottom wall 18. The light-receiving element 12 has a pair of side surfaces 12b and 12c facing opposite each other in the direction D2. The light-receiving element 12 converts light incident on the light-receiving surface 121a into an electrical signal and outputs the converted electrical signal to the processing unit 7. The light-receiving element 12 has wiring (not shown) to which a wire 16 for outputting the electrical signal is connected.

[0038] The fiber optic plate (hereinafter also referred to as "FOP") 13 is an optical component formed by bundling multiple optical fibers. The FOP 13 includes, for example, tens of millions of optical fibers having diameters of several nanometers to several tens of nanometers. The FOP 13 has a rectangular parallelepiped shape and includes an input surface 13a, an output surface 13b, and a pair of side surfaces 13c and 13d connecting the input surface 13a and the output surface 13b. The input surface 13a is formed by one end surface of multiple optical fibers included in the FOP 13, and the output surface 13b is formed by the other end surfaces of the multiple optical fibers. In this embodiment, the input surface 13a and the output surface 13b are parallel to each other and face opposite each other in the direction D1. The pair of side surfaces 13c and 13d face opposite each other in the direction D2.

[0039] The FOP 13 is disposed on the light receiving element 12 so that the input surface 13a and output surface 13b are parallel to the light receiving surface 121a of the light receiving element 12 and the output surface 13b faces the light receiving surface 121a. Light incident on the input surface 13a of the FOP 13 propagates through the optical fibers that make up the FOP 13 and is emitted from the output surface 13b toward the light receiving surface 121a. The light incident on the input surface 13a is emitted from the output surface 13b without spreading within the FOP 13.

[0040] The first resin member 14 is disposed between the light-receiving surface 121a and the output surface 13b and bonds the FOP 13 to the light-receiving element 12. The first resin member 14 is in contact with the light-receiving surface 121a and the output surface 13b. In this embodiment, the first resin member 14 is in contact with the entire output surface 13b and a central portion of the top surface 12a, including the light-receiving surface 121a. The first resin member 14 is not in contact with the outer edge portion of the top surface 12a. When viewed from direction D1, the outer edge of the first resin member 14 overlaps with the outer edge of the FOP 13, and the first resin member 14 does not protrude outside the FOP 13. In other words, when viewed from direction D1, the shape of the first resin member 14 is the same as the shape of the FOP 13.

[0041] The first resin member 14 is made of an adhesive film, such as a die attach film. The die attach film is formed in a film shape, and objects to be joined can be attached to both sides of the film. For example, the die attach film is heated and hardened, thereby adhering to the objects to be joined.

[0042] The anti-reflection layer 15 is formed in the form of a film on the input surface 13a, and prevents reflection of light on the input surface 13a. The anti-reflection layer 15 is formed over the entire input surface 13a.

[0043] The wire 16 is a bonding wire connected to the bottom wall 18 and the light-receiving element 12. One end of the wire 16 is connected to an exposed portion of the wiring on the surface 18a of the bottom wall 18, and the other end of the wire 16 is connected to an exposed portion of the wiring on the top surface 12a of the light-receiving element 12. The wire 16 is curved so as to be convex toward the side opposite the bottom wall 18 (the side where the light-receiving element 12 is located relative to the bottom wall 18).

[0044] The second resin member 17 is disposed on the surface 18a of the bottom wall portion 18 and supports the light-receiving element 12 and the FOP 13. The second resin member 17 is disposed on both sides of the FOP 13 in the direction D2. The second resin member 17 is in contact with the light-receiving element 12, the FOP 13, and the first resin member 14. More specifically, the second resin member 17 is in contact with the exposed portion of the surface 18a from the light-receiving element 12, the exposed portion of the upper surface 12a of the light-receiving element 12 from the first resin member 14, the side surfaces 12b and 12c, the outer edge portion 14a of the first resin member 14, and the side surfaces 13c and 13d of the FOP 13. In this embodiment, the second resin member 17 is in contact with the region of each side surface 13c and 13d on the first resin member 14 side, but is not in contact with the region on the anti-reflection layer 15 side.

[0045] The second resin member 17 covers the wire 16. In this embodiment, the second resin member 17 covers the entire wire 16. That is, the wire 16 is not exposed from the second resin member 17. The second resin member 17 is formed so as not to reach the peripheral edge portion 18b of the surface 18a. That is, the peripheral edge portion 18b is exposed from the second resin member 17. The peripheral edge portion 18b is a rectangular frame-shaped portion extending along the outer edge of the surface 18a so as to surround the light receiving element 12 and the second resin member 17 when viewed from the direction D1, for example.

[0046] The first resin member 14 is formed from a first resin material, and the second resin member 17 is formed from a second resin material. The first resin material and the second resin material are different from each other. The first resin material may be composed of one material or multiple materials. Similarly, the second resin material may be composed of one material or multiple materials. The first resin material and the second resin material being different from each other means that the first resin material and the second resin material are different from each other in terms of type or ratio. The first resin material and the second resin material being different from each other in terms of type means that one of the first resin material and the second resin material contains at least one material that is not contained in the other. Furthermore, the first resin material and the second resin material being different from each other in terms of ratio means that the ratio of the materials contained in the first resin material is different from the ratio of the materials contained in the second resin material. In other words, even if the first resin material and the second resin material are composed of the same material, if the ratio of the materials is different, the first resin material and the second resin material can be said to be different from each other. Because the first resin material and the second resin material are different from each other, the first resin member 14 and the second resin member 17 have different properties (e.g., light transmittance, hardness, etc.). The first resin material is, for example, a silicone resin or an acrylic resin. The second resin material is, for example, an epoxy resin. The first resin member and the second resin material are thermosetting resins or thermoplastic resins, preferably thermosetting resins.

[0047] In this embodiment, the light transmittance of the second resin member 17 is lower than that of the first resin member 14. In other words, the light blocking property of the second resin member 17 is higher than that of the first resin member 14. In this case, the light transmittance refers to the light transmittance for light having the wavelength of the light emitted from the light source 5, for example, the light transmittance for light with a wavelength of 800 nm to 900 nm. The light transmittance of the first resin member 14 may be, for example, 90% or more, and the light transmittance of the second resin member 17 may be, for example, 5% or less.

[0048] In this embodiment, the second resin member 17 is harder than the first resin member 14. In this example, the Young's modulus of the second resin member 17 is higher than the Young's modulus of the first resin member 14. The Young's modulus of the first resin member 14 is, for example, 1×10 ６ The Young's modulus of the second resin member 17 may be, for example, about 8×10 ９ The optical module manufacturing method may be on the order of Pa.

[0049] A method for manufacturing the optical module 6 will be described with reference to FIGS. 3 to 5 . An example of manufacturing multiple optical modules 6 at once will be described below. First, a rectangular plate-shaped substrate 20 (third substrate) is prepared ( FIG. 3( a) ). The substrate 20 has multiple bottom wall portions 21, each corresponding to a bottom wall portion 18. The "bottom wall portions corresponding to the bottom wall portions" refer to the portions that will become the bottom wall portions 18 after the cutting process of the substrate 20. The multiple bottom wall portions 21 are arranged in a grid pattern on the substrate 20, and boundaries L1 (dicing lines) are set between adjacent bottom wall portions 21. The substrate 20 is cut (diced) along the boundaries L1 in a subsequent cutting process. Each bottom wall portion 21 has a surface 21a that will become the surface 18a after the cutting process. Wiring is formed on the bottom wall portion 21, and the wiring has terminals 22 exposed on the surface 21a. The following process is performed for each bottom wall portion 21.

[0050] Next, as shown in FIG. 3A, the light receiving element 12 is placed on the surface 21a (surface 18a) of the bottom wall portion 21 so that the light receiving surface 121a faces away from the bottom wall portion 21 (first step).

[0051] 3B, the light receiving element 12 and the bottom wall portion 21 are connected by the wire 16. More specifically, one end of the wire 16 is connected to the terminal 22 of the bottom wall portion 21, and the other end of the wire 16 is connected to the exposed portion of the wiring of the light receiving element 12 on the top surface 12a.

[0052] Here, the formation process for forming the FOP 13 used in the second process described below will be described with reference to FIG. 4 . First, a rectangular plate-shaped substrate 30 (first substrate) is prepared ( FIG. 4( a) ). The substrate 30 is formed by bundling a plurality of optical fibers, and has a plurality of portions 31, each of which corresponds to the FOP 13. The "portions corresponding to the FOP" are the portions that will become the FOP 13 after the substrate 30 is cut. The portions 31 are arranged in a lattice pattern on the substrate 30, and boundaries L2 (dicing lines) are set between adjacent portions 31. The substrate 20 is cut (diced) along the boundaries L2 in a later cutting process.

[0053] Next, as shown in FIG. 4( a), a film-like substrate 40 (second substrate) is attached to one main surface of the substrate 30. The substrate 40 is an adhesive film having a plurality of portions 41, each of which corresponds to the first resin member 14, and is a die attach film in this embodiment. The "portions corresponding to the first resin members" are the portions that will become the first resin members 14 after the substrate 40 is cut. The plurality of portions 41 are positioned in a lattice pattern on the substrate 40, and a boundary L2 common to the substrate 30 is set between adjacent portions 41. Each portion 41 overlaps the corresponding portion 31. The substrate 40 is cut along the boundary L2 together with the substrate 30.

[0054] Next, a substrate 50 is formed on the other main surface of the substrate 30. The substrate 50 is a thin film having a plurality of portions 51, each of which corresponds to the antireflection layer 15. The "portions corresponding to the antireflection layer" are portions that will become the antireflection layer 15 after the cutting process of the substrate 50. The substrate 50 is formed, for example, by applying a coating process to the other main surface of the substrate 30. The plurality of portions 51 are positioned in a lattice pattern on the substrate 50, and a boundary L2 common to the substrate 30 is set between adjacent portions 51. Each portion 51 overlaps a corresponding portion 31. The substrate 50 is cut along the boundary L2 together with the substrate 30.

[0055] Next, as shown in FIG. 4( b), the laminate consisting of the substrate 30, the substrate 40, and the substrate 50 is cut together along the boundary L2 to obtain multiple FOPs 13. In this cutting process, the substrate 40 may be used as a fixing member to fix the laminate. For example, the substrate 40 may have dicing tape on the surface opposite the substrate 30, and the dicing tape may be used to fix the laminate to a base (e.g., a dicing frame) on which it is placed during the cutting process. The dicing tape is peeled off before the next second process is performed. Each of the obtained FOPs 13 has a first resin member 14 attached to one surface and an anti-reflection layer 15 formed on the other surface. The surface of the FOP 13 to which the first resin member 14 is attached corresponds to the output surface 13b, and the surface of the FOP 13 to which the anti-reflection layer 15 is formed corresponds to the input surface 13a.

[0056] 5A, the FOP 13 is positioned so that the output surface 13b of the FOP 13 faces the light-receiving surface 121a of the light-receiving element 12, and the FOP 13 is bonded to the light-receiving element 12 with a first resin member 14 disposed between the light-receiving surface 121a and the output surface 13b (step 2). If the first resin member 14 is a thermosetting resin, the first resin member 14 is bonded to the light-receiving surface 121a and the output surface 13b by, for example, heating and hardening the first resin member 14. If the first resin member 14 is a thermoplastic resin, the first resin member 14 is heated to soften it and then hardened to bond the surface of the first resin member 14 to the light-receiving surface 121a and the output surface 13b. This bonds the FOP 13 to the light-receiving element 12 via the first resin member 14. For example, when the first resin material is a thermosetting resin, if an acrylic resin is used as the thermosetting resin, the first resin member 14 hardens at about 150° C., and if a silicone resin is used as the thermosetting resin, the first resin member 14 hardens at room temperature (5° C. to 35° C.). Note that when the first resin member 14 is a thermosetting resin that hardens at room temperature, the heat treatment includes heating the first resin member 14 from a temperature lower than room temperature to a temperature higher than room temperature.

[0057] Next, as shown in FIG. 5B , the second resin member 17 is placed on the surface 18a of the bottom wall 18 so as to contact the light receiving element 12, the FOP 13, and the first resin member 14 (step 3). In step 3, if the second resin member 17 is a thermosetting resin, the second resin member 17 is placed on the surface 18a and then heated to harden it. If the second resin member 17 is a thermoplastic resin, the second resin member 17 is heated and melted, and then placed on the surface 18a and then hardened. If the second resin member 17 is a thermosetting resin that hardens at room temperature, the heating process includes heating the second resin member 17 from a temperature below room temperature to a temperature above room temperature. The second resin members 17 are placed on both sides of the FOP 13 in a direction perpendicular to the thickness direction of the substrate 20 so as to completely cover each wire 16.

[0058] In this embodiment, the viscosity of the first resin member 14 before being cured in the second step is lower than the viscosity of the second resin member 17 before being cured in the third step. When the resin members are thermoplastic resins, the "viscosity of the resin members before being cured" refers to the viscosity of the resin members in a softened state after being heated. Furthermore, when the first resin member 14 and the second resin member 17 are thermosetting resins that cure at temperatures higher than room temperature, the viscosity of the first resin member 14 at room temperature before being cured may be, for example, 10 Pa·s or less, and the viscosity of the second resin member 17 at room temperature before being cured may be, for example, 200 Pa·s or more.

[0059] In the third step, the second resin member 17 is placed on the surface 18a of the bottom wall portion 18 so that the second resin member 17 is separated from the boundary L1 (so that it does not reach the boundary L1). As a result, after curing, the peripheral edge portion 18b of the bottom wall portion 21 (bottom wall portion 18) is exposed from the second resin member 17. In this example, the high viscosity of the heated second resin member 17 prevents the second resin member 17 from reaching the boundary L1. In other words, the viscosity of the second resin member 17 is adjusted so that the second resin member 17 does not reach the boundary L1.

[0060] Next, the substrate 20 is cut along the boundary L1 to obtain a plurality of optical modules 6 (fourth step). This completes the manufacturing process of the optical module 6. [Operation and Effects]

[0061] The optical module 6 includes a first resin member 14 disposed between the light-receiving surface 121a of the light-receiving element 12 and the output surface 13b of the FOP 13 to bond the FOP 13 to the light-receiving element 12, and a second resin member 17 disposed on the surface 18a of the bottom wall 18 so as to contact the light-receiving element 12 and the FOP 13. This allows the first resin member 14 to firmly bond the FOP 13 to the light-receiving element 12, while the second resin member 17 reliably supports the FOP 13 and the light-receiving element 12. Furthermore, the first resin member 14 and the second resin member 17 are made of different materials. This allows for greater freedom in selecting the materials for the first resin member 14 and the second resin member 17, thereby enabling designs tailored to required performance. For example, the first resin member 14 can be made of a material with high light transmittance, and the second resin member 17 can be made of a material with low light transmittance. In this case, the first resin member 14 can prevent light from traveling from the FOP 13 toward the light-receiving element 12 from being blocked, while the second resin member 17 can block noise light traveling toward the light-receiving element 12 from the side. As a result, detection accuracy can be improved. As another example, the first resin member 14 can be formed from a soft material, and the second resin member 17 can be formed from a hard material. In this case, the FOP 13 and the light-receiving element 12 can be more reliably supported by the second resin member 17 while preventing peeling between the FOP 13 and the light-receiving element 12, which are joined by the first resin member 14. As a result, the FOP 13 can be stably positioned on the light-receiving element 12. As yet another example, the first resin member 14 can be formed from a material with low viscosity before curing, and the second resin member 17 can be formed from a material with high viscosity before curing. In this case, the generation of air bubbles or the like in the first resin member 14 after hardening can be suppressed, allowing the FOP 13 to be stably positioned on the light-receiving element 12, and manufacturing efficiency can be improved by omitting a structure (e.g., a side wall portion) for blocking the second resin member 17 before hardening. In this way, the optical module 6 can be designed to meet required performance requirements.

[0062] The second resin member 17 covers the wire 16. This makes it possible to protect the wire 16 from oil that may be scattered when the encoder 1 is in use, physical external forces, and the like.

[0063] The peripheral edge 18b of the surface 18a of the bottom wall 18 is exposed from the second resin member 17. That is, the second resin member 17 is formed so as not to reach the peripheral edge 18b of the surface 18a of the bottom wall 18. During the manufacture of the optical module 6, the uncured second resin member 17 may be disposed on the surface 18a. However, if the second resin member 17 is formed so as not to reach the peripheral edge 18b of the surface 18a, it is not necessary to provide a structure (e.g., a side wall) on the bottom wall 18 to block the uncured second resin member 17. This eliminates the need to provide a structure on the bottom wall 18 to block the uncured second resin member 17, thereby improving manufacturing efficiency. Furthermore, since it is not necessary to provide a structure on the bottom wall 18 to block the second resin member 17, the area of ​​the bottom wall 18 can be reduced, allowing more optical modules 6 to be manufactured from a single substrate 20.

[0064] The first resin member 14 is an adhesive film (die attach film). This allows the heated first resin member 14 to harden in a relatively short time, thereby enabling the first resin member 14 to bond the FOP 13 to the light-receiving element 12 with high precision. That is, for example, if the first resin member 14 is not an adhesive film but a resin member that requires time to harden after heating, the FOP 13 may shift out of position before the resin material hardens. In contrast, if the first resin member 14 is an adhesive film, the heated first resin member 14 hardens in a relatively short time, preventing such misalignment of the FOP 13. This allows the first resin member 14 to bond the FOP 13 to the light-receiving element 12 with high precision. As a result, yield can be improved.

[0065] When viewed from direction D1, the outer edge of the first resin member 14 overlaps the outer edge of the FOP 13. As a result, when viewed from direction D1, the first resin member 14 does not protrude outside the FOP 13, thereby reducing the contact area between the first resin member 14 and the second resin member 17. Therefore, when the first resin member 14 and the second resin member 17 thermally contract or expand due to a change in environmental temperature, damage to the contact points between the first resin member 14 and the second resin member 17 can be suppressed.

[0066] The light transmittance of the second resin member 17 is lower than the light transmittance of the first resin member 14. This prevents the light traveling from the FOP 13 toward the light receiving element 12 from being blocked by the first resin member 14, while allowing the second resin member 17 to block noise light traveling toward the light receiving element 12 from the side. As a result, detection accuracy can be improved.

[0067] The second resin member 17 is harder than the first resin member 14. This makes it possible to more reliably support the FOP 13 and the light receiving element 12 by the second resin member 17 while suppressing separation between the FOP 13 and the light receiving element 12 that are joined by the first resin member 14. As a result, the FOP 13 can be stably positioned on the light receiving element 12.

[0068] The optical module 6 includes an anti-reflection layer 15 formed on the input surface 13a of the FOP 13. This makes it possible to suppress reflection of light on the input surface 13a of the FOP 13, thereby improving detection accuracy.

[0069] The FOP 13 has a pair of side surfaces 13c and 13d facing opposite each other in the direction D2, and the second resin member 17 is in contact with both of the pair of side surfaces 13c and 13d. This makes it possible to more reliably support the light receiving element 12 and the FOP 13.

[0070] In the manufacturing method of the optical module according to the embodiment, after the second step of bonding the FOP 13 to the light-receiving element 12 with the first resin member 14, a third step of arranging the second resin member 17 on the surface 18a of the bottom wall portion 18 so as to contact the light-receiving element 12, the first resin member 14, and the FOP 13 is performed. This makes it possible to prevent the position of the FOP 13 from shifting relative to the light-receiving element 12 during manufacturing, thereby suppressing a decrease in yield. That is, for example, if the first resin member 14 is omitted and the light-receiving element 12 and the FOP 13 are also bonded by the second resin member 17 (if the first resin member 14 and the second resin member 17 are made of a single resin member), it takes a relatively long time for the second resin member 17 to harden, and therefore the position of the FOP 13 may shift before the second resin member 17 hardens. In contrast, in the manufacturing method of the optical module according to the embodiment, the FOP 13 is joined to the light receiving element 12 using the first resin member 14, and then the second resin member 17 is placed on the surface 18a of the bottom wall portion 18, thereby suppressing such misalignment of the FOP 13 and improving yield.

[0071] The viscosity of the first resin member 14 before curing in the second step is lower than the viscosity of the second resin member 17 before curing in the third step. The low viscosity of the first resin member 14 before curing prevents air bubbles from forming in the cured first resin member 14, allowing the FOP 13 to be stably positioned on the light-receiving element 12. Furthermore, the high viscosity of the second resin member 17 before curing allows for the omission of a structure for blocking the second resin member 17 (e.g., a sidewall), improving manufacturing efficiency. Furthermore, because a structure for blocking the second resin member 17 does not need to be disposed on the bottom wall 18, the area of ​​the bottom wall 18 can be reduced, allowing more optical modules 6 to be manufactured from a single substrate 20.

[0072] The forming process of the FOP 13 includes, in this order, a step of attaching a base material 40 having a plurality of portions 41 corresponding to the first resin member 14 to a base material 30 having a plurality of portions 31 corresponding to the FOP 13, and a step of cutting the base material 30 and the base material 40 to obtain a plurality of FOPs 13 to which the first resin members 14 are attached. This improves manufacturing efficiency compared to, for example, attaching the first resin members 14 individually to a plurality of FOPs 13.

[0073] In the first step, for each of the plurality of bottom wall portions 21, the light-receiving element 12 is placed on the surface 18a of the bottom wall portion 18 so that the light-receiving surface 121a faces away from the bottom wall portion 18. In the second step, for each of the plurality of bottom wall portions 21, the FOP 13 is placed on the light-receiving element 12 so that the output surface 13b faces the light-receiving surface 121a, and the FOP 13 is bonded to the light-receiving element 12 with the first resin member 14 placed between the light-receiving surface 121a and the output surface 13b. In the third step, for each of the plurality of bottom wall portions 21, the second resin member 17 is placed on the surface 18a of the bottom wall portion 18 so as to contact the light-receiving element 12, the first resin member 14, and the FOP 13. After the third step, the substrate 20 is cut to obtain a plurality of optical modules 6. This improves manufacturing efficiency compared to, for example, placing the light-receiving elements 12, etc. individually on a plurality of individual bottom wall portions 18.

[0074] In the third step, the second resin member 17 is disposed on the surface 18a of the bottom wall portion 18 so that the second resin member 17 is spaced apart from the boundary L1 between the plurality of bottom wall portions 21. This eliminates the need to provide a structure (e.g., a side wall portion) on the boundary L1 to block the uncured second resin member 17, thereby improving manufacturing efficiency.

[0075] The optical module 6 may be configured as shown in a modified example in FIG. 6 . In this modified example, the support 11 further includes a sidewall 19 disposed on the surface 18a of the bottom wall 18. The sidewall 19 is formed along the outer edge of the surface 18a and has a rectangular frame shape when viewed from the direction D1. When viewed from the direction D1, the sidewall 19 surrounds the light receiving element 12, the FOP 13, the first resin member 14, the anti-reflection layer 15, the wires 16, and the second resin member 17. The sidewall 19 may be formed from the same material as the bottom wall 18 (e.g., glass epoxy resin). In this modified example, the second resin member 17 contacts the inner surface 19a of the sidewall 19 but does not contact the end surface 19b of the sidewall 19 opposite the bottom wall 18.

[0076] This modification also allows for a design tailored to required performance, similar to the above embodiment. In this modification, the support 11 further includes a sidewall 19 disposed on the surface 18a of the bottom wall 18. When viewed from the direction D1, the sidewall 19 surrounds the light-receiving element 12 and the second resin member 17, and the second resin member 17 is in contact with the sidewall 19. In this case, the uncured second resin member 17 can be blocked by the sidewall 19 during manufacturing of the optical module 6. This allows a low-viscosity material to be used for the second resin member 17, further increasing the degree of freedom in selecting the materials for the first resin member 14 and the second resin member 17. Furthermore, the sidewall 19 protects the light-receiving element 12 from physical contact.

[0077] The present disclosure is not limited to the above-described embodiment and modified examples. For example, the materials and shapes of each component are not limited to those described above, and various materials and shapes can be used. For example, the first resin member 14 may be formed by hardening a resin material that has been heated and melted. When viewed from direction D1, the outer edge of the first resin member 14 does not have to overlap with the outer edge of the FOP 13. The outer edge of the first resin member 14 may be located inside or outside the outer edge of the FOP 13.

[0078] The light transmittance of the second resin member 17 may be higher than the light transmittance of the first resin member 14. The hardness of the second resin member 17 may be lower than the hardness of the first resin member 14. The viscosity of the first resin member 14 heated in the second step may be higher than the viscosity of the second resin member 17 heated in the third step.

[0079] The second resin member 17 may be disposed over the entire surface 18a of the bottom wall portion 18. In this case, a peripheral edge portion 18b of the surface 18a may not be exposed from the second resin member 17. The second resin member 17 may not cover the entire wire 16, but may cover only a portion of the wire 16. The second resin member 17 may not be in contact with the side wall portion 19. When the side wall portion 19 is disposed on the bottom wall portion 18, the inner portion of the surface 18a of the bottom wall portion 18 adjacent to the side wall portion 19 may be the peripheral edge portion 18b of the surface 18a, and the peripheral edge portion 18b may be exposed from the second resin member 17.

[0080] In the manufacturing method of the optical module 6 according to the above embodiment, after the base material 20 is cut to obtain a plurality of bottom wall portions 18, the light receiving element 12 may be disposed on the surface 18a of each bottom wall portion 18. After the base material 30 is cut to obtain a plurality of FOPs 13, the first resin member 14 and the anti-reflection layer 15 may be disposed on each FOP 13.

[0081] In the above embodiment, the first resin member 14 was attached to the output surface 13b of the FOP 13, and then the FOP 13 with the first resin member 14 attached was placed on the light receiving surface 121a of the light receiving element 12, but the FOP 13 may also be placed on the first resin member 14 after the first resin member 14 is placed (attached) on the light receiving surface 121a.

[0082] The encoder 1 may be a reflective encoder. In this case, the light source 5 is arranged on the same side of the rotating plate 3 as the optical module 6. The light source 5 may be arranged, for example, on the surface 18a of the bottom wall 18. That is, the optical module 6 may include a light-emitting element arranged on the surface 18a of the bottom wall 18. The rotating plate 3 may have a light-reflecting pattern that reflects light emitted from the light source 5, instead of the light-transmitting pattern 3a. In this case, the light emitted from the light source 5 is reflected by the light-reflecting pattern of the rotating plate 3 and then enters the light-receiving element 12.

[0083] The number of light receiving portions 121 (light receiving surfaces 121a) of the light receiving element 12 is not limited and may be one or more. The light receiving element 12 may be connected to the wiring on the bottom wall portion 18 via bumps instead of wires 16. The anti-reflection layer 15 may be formed only on a portion of the input surface 13a, or may be omitted. The first resin material and the second resin material may be the same.

[0084] 1...encoder, 3...rotating plate, 3a...light transmission pattern, 5...light source, 6...optical module (optical module for encoder), 11...support, 12...light receiving element, 121a...light receiving surface, 13...FOP (fiber optic plate), 13a...input surface, 13b...output surface, 13c, 13d...side surface, 14...first resin member, 15...anti-reflection layer, 16...wire, 17...second resin member, 18...bottom wall portion, 18a...surface, 18b...periphery, 19...side wall portion, 20...substrate (third substrate), 21...bottom wall portion, 30...substrate (first substrate), 31...portion, 40...substrate (second substrate), 41...portion, L1...boundary.

Claims

1. An optical module for an encoder comprising: a support having a bottom wall; a light-receiving element having a light-receiving surface and arranged on the surface of the bottom wall so that the light-receiving surface faces away from the bottom wall; a fiber optic plate having an input surface formed by one end faces of a plurality of optical fibers and an output surface formed by the other end faces of the plurality of optical fibers, the fiber optic plate being arranged on the light-receiving element so that the output surface faces the light-receiving surface; a first resin member arranged between the light-receiving surface and the output surface and bonding the fiber optic plate to the light-receiving element; and a second resin member arranged on the surface of the bottom wall so as to contact the light-receiving element and the fiber optic plate, wherein the first resin member and the second resin member are made of different materials.

2. The optical module for an encoder according to claim 1, further comprising a wire connected to the bottom wall portion and the light receiving element, the second resin member covering the wire.

3. The optical module for an encoder according to claim 1 or 2, wherein the peripheral edge of the surface of the bottom wall portion is exposed from the second resin member.

4. An optical module for an encoder as described in claim 1 or 2, wherein the support further has a side wall portion arranged on the surface of the bottom wall portion, the side wall portion surrounding the light receiving element and the second resin member when viewed from the thickness direction of the bottom wall portion, and the second resin member contacting the side wall portion.

5. An optical module for an encoder according to any one of claims 1 to 4, wherein the first resin member is an adhesive film.

6. An optical module for an encoder according to any one of claims 1 to 5, wherein the first resin member is a die attach film.

7. An optical module for an encoder as described in any one of claims 1 to 6, wherein when viewed from the thickness direction of the bottom wall portion, the outer edge of the first resin member overlaps with the outer edge of the fiber optic plate.

8. An optical module for an encoder according to any one of claims 1 to 7, wherein the second resin member has a lower light transmittance than the first resin member.

9. An optical module for an encoder according to any one of claims 1 to 8, wherein the second resin member is harder than the first resin member.

10. An optical module for an encoder according to any one of claims 1 to 9, further comprising an anti-reflection layer formed on the input surface of the fiber optic plate.

11. An optical module for an encoder according to any one of claims 1 to 10, wherein the fiber optic plate has a pair of side surfaces facing opposite each other in a direction perpendicular to the thickness direction of the bottom wall portion, and the second resin member is in contact with both of the pair of side surfaces.

12. An encoder comprising: a rotating plate having a light-transmitting pattern or a light-reflecting pattern; and an optical module for an encoder according to any one of claims 1 to 11, which is arranged so that light that has passed through the light-transmitting pattern or light that has been reflected by the light-reflecting pattern is incident on the light-receiving element.

13. A method for manufacturing an optical module for an encoder, comprising: a support having a bottom wall portion; a light-receiving element having a light-receiving surface; a fiber optic plate having an input surface formed by one end faces of a plurality of optical fibers and an output surface formed by the other end faces of the plurality of optical fibers; a first resin member for bonding the fiber optic plate to the light-receiving element; and a second resin member arranged on the surface of the bottom wall portion, the method comprising, in this order: a first step of arranging the light-receiving element on the surface of the bottom wall portion so that the light-receiving surface faces away from the bottom wall portion; a second step of arranging the fiber optic plate on the light-receiving element so that the output surface faces the light-receiving surface, and bonding the fiber optic plate to the light-receiving element with the first resin member arranged between the light-receiving surface and the output surface; and a third step of arranging the second resin member on the surface of the bottom wall portion so that it comes into contact with the light-receiving element and the fiber optic plate, wherein the materials of the first resin member and the second resin member are different from each other.

14. A method for manufacturing an optical module for an encoder according to claim 13, wherein the first resin member is an adhesive film.

15. A method for manufacturing an optical module for an encoder according to claim 13 or 14, wherein the first resin member is a die attach film.

16. A method for manufacturing an optical module for an encoder as described in any one of claims 13 to 15, wherein in the second step, the first resin member is hardened to bond the fiber optic plate to the light receiving element, and in the third step, the second resin member is placed on the surface of the bottom wall portion and then hardened, and the viscosity of the first resin member before hardening in the second step is lower than the viscosity of the second resin member before hardening in the third step.

17. A method for manufacturing an optical module for an encoder as described in any one of claims 13 to 16, further comprising a forming step of forming the fiber optic plate before the second step, the forming step including the steps of: attaching a second substrate having a plurality of portions corresponding to the first resin member to a first substrate having a plurality of portions corresponding to the fiber optic plate; and cutting the first substrate and the second substrate to obtain a plurality of the fiber optic plates to which the first resin member is attached.

18. A method for manufacturing an optical module for an encoder according to any one of claims 13 to 17, further comprising: a third base material having a plurality of bottom wall portions corresponding to the bottom wall portion; in the first step, for each of the plurality of bottom wall portions, the light-receiving element is arranged on the surface of the bottom wall portion so that the light-receiving surface faces away from the bottom wall portion; in the second step, for each of the plurality of bottom wall portions, the fiber optic plate is arranged on the light-receiving element so that the output surface faces the light-receiving surface, and the fiber optic plate is joined to the light-receiving element by the first resin member arranged between the light-receiving surface and the output surface; in the third step, for each of the plurality of bottom wall portions, the second resin member is arranged on the surface of the bottom wall portion so as to be in contact with the light-receiving element, the first resin member, and the fiber optic plate; and after the third step, a fourth step of obtaining a plurality of the optical modules for an encoder by cutting the third base material.

19. A method for manufacturing an optical module for an encoder as described in claim 18, wherein in the third step, the second resin member is placed on the surface of the bottom wall portion so that the second resin member is spaced apart from the boundaries between the multiple bottom wall portions.

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