Encoder light receiving module and encoder

Abstract

The light receiving module (6) of the present invention comprises: a support body (11) having a bottom wall portion (16) and a side wall portion (17); a light receiving element (12) arranged on the bottom wall portion (16) with a light receiving surface (21a) facing one side (S) and surrounded by the side wall portion (17) when viewed from the one side (S); and an optical fiber plate (13) having an input surface (13a) formed by one end surface of a plurality of optical fibers and an output surface (13b) formed by the other end surface of the plurality of optical fibers, and arranged on the light receiving element (12) with the output surface (13b) facing the light receiving surface (21a). The end surface (17b) on one side (S) of the side wall portion (17) is located closer to the one side (S) than the light receiving surface (21a), and the input surface (13a) is located closer to the one side (S) than the end surface (17b).

Description

Technical Field

[0001] One aspect of the present invention relates to a light receiving module for an encoder and an encoder. Background Art

[0002] An encoder is known that includes a rotating plate having a light-passing pattern, a light source disposed on one side of the rotating plate, and a light-receiving element disposed on the other side of the rotating plate (see, for example, Patent Document 1).

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-37333 Summary of the Invention

[0006] [Problems to be solved by the invention]

[0007] In the encoder as described above, in order to, for example, protect the light-receiving element from physical contact, it is considered to arrange the light-receiving element on a support body having a bottom wall portion and a side wall portion. More specifically, it is considered to arrange the light-receiving element on the bottom wall portion in a manner that it is surrounded by the side wall portion when viewed from one side. However, even if the light-receiving element is arranged on the bottom wall portion in a manner that the light-receiving surface faces one side, the light-receiving surface can only be brought close to the light-transmitting pattern before the side wall portion contacts the rotating plate. In the case where a fixed plate having a light-transmitting pattern is provided together with the rotating plate, the light-receiving surface can only be brought close to the light-transmitting pattern before the side wall portion contacts the rotating plate or the fixed plate. If the light-receiving surface cannot be brought close to the light-transmitting pattern, there is a concern that the detection accuracy of the encoder will be reduced due to the diffusion of light, etc.

[0008] Therefore, one object of the present invention is to provide a light-receiving module for an encoder that can achieve good detection accuracy when used in an encoder while protecting a light-receiving element, and an encoder including such a light-receiving module.

[0009] [Technical means to solve the problem]

[0010] An encoder light receiving module according to one aspect of the present invention comprises: a support body having a bottom wall portion and a side wall portion arranged on the bottom wall portion on one side of the bottom wall portion; a light receiving element having a light receiving surface and being arranged on the bottom wall portion with the light receiving surface facing one side and surrounded by the side wall portion when viewed from one side; and an optical fiber plate having an input surface composed of one end surface of a plurality of optical fibers and an output surface composed of the other end surface of the plurality of optical fibers and being arranged on the light receiving element with the output surface facing the light receiving surface; and the end surface on one side of the side wall portion is located closer to the side than the light receiving surface, and the input surface is located closer to the side than the end surface.

[0011] In the light-receiving module for the encoder, the end face of one side of the side wall portion is located at a position closer to the side than the light-receiving surface of the light-receiving element. Thus, for example, the light-receiving element can be reliably protected from physical contact. In addition, the optical fiber plate is arranged on the light-receiving element in such a manner that the output surface is opposite to the light-receiving surface. Thus, light incident on the input surface can be reliably guided to the light-receiving surface. Furthermore, the input surface of the optical fiber plate is located at a position closer to the side than the end face of one side of the side wall portion. Thus, the input surface can be brought closer to the light-passing pattern of the encoder. As a result, the diffusion of light passing through the light-passing pattern and its incidence on the light-receiving surface can be suppressed. Therefore, according to the light-receiving module for the encoder, it is possible to protect the light-receiving element while obtaining good detection accuracy when applied to the encoder.

[0012] An encoder light receiving module according to one aspect of the present invention may further include: a wire connected to the wiring provided on the bottom wall and the terminal provided on the light receiving element on the inner side of the side wall; and a resin member disposed on the bottom wall on the inner side of the side wall and covering the wiring, terminal, and wire; the end face of the resin member is located further to the side of the wire, and the input surface is located further to the side of the resin member. Thus, since the wiring, terminal, and wire are covered by the resin member, they are protected from oil, etc., which may be scattered during use of the encoder. Furthermore, since the end face of the side wall is located further to the side of the wire, external forces acting on the wire are suppressed. Furthermore, the input surface can be brought closer to the light transmission pattern of the encoder without being obstructed by the resin member.

[0013] In the encoder light receiving module according to one aspect of the present invention, the optical fiber plate may be fixed to the light receiving element via a resin member. This can omit the structure for fixing the optical fiber plate to the light receiving element, thereby simplifying the structure.

[0014] The light-receiving module for an encoder according to one aspect of the present invention may further include a light-shielding layer having a light-passing pattern and disposed between the light-receiving surface and the output surface. This allows light passing through the light-passing pattern of the rotating plate of the encoder to be appropriately incident on the light-receiving surface. Furthermore, since the light-passing pattern of the light-shielding layer is relatively close to the light-receiving surface, the positional accuracy between the light-passing pattern of the light-shielding layer and the light-receiving surface can be improved. Furthermore, since the light-passing pattern of the light-shielding layer and the light-receiving surface are imaged to the input surface via the output surface, the light-passing pattern of the light-shielding layer and the light-receiving surface can be optically brought close to the light-passing pattern of the rotating plate. As a result, the detection accuracy in the case of an encoder is improved.

[0015] An encoder according to one aspect of the present invention comprises a rotating plate having a light-transmitting pattern, a light source disposed on one side of the rotating plate, and the aforementioned encoder light-receiving module disposed on the other side of the rotating plate. This encoder, as described above, achieves excellent detection accuracy while protecting the light-receiving element.

[0016] [Effects of the Invention]

[0017] According to one aspect of the present invention, there are provided a light receiving module for an encoder that can achieve good detection accuracy when used in an encoder while protecting a light receiving element, and an encoder including the light receiving module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A perspective view of an encoder according to one embodiment.

[0019] Figure 2 for Figure 1 The top view of the light receiving module is shown.

[0020] Figure 3 To follow Figure 2 Cross-sectional view along line III-III.

[0021] Figure 4 2 is a cross-sectional view of a light receiving module according to a modified example. DETAILED DESCRIPTION

[0022] Hereinafter, an embodiment of one aspect of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and repeated description will be omitted.

[0023] like Figure 1 As shown, encoder 1 includes a rotating shaft 2, a rotating plate 3, a fixed plate 4, a light source 5, a light receiving module 6, and a processing unit 7. Rotating shaft 2 rotates about axis A. Encoder 1 is a so-called absolute rotary encoder and is a device for detecting the absolute angle of a measurement object connected to rotating shaft 2.

[0024] The rotating plate 3 is fixed to the rotating shaft 2 and rotates together with the rotating shaft 2. The rotating plate 3 is formed into a circular plate, for example, and is attached to the rotating shaft 2 at its center, perpendicular to the axis A. The rotating plate 3 has a light-transmitting pattern 3a representing a specific pattern such as a Gray code. The light-transmitting pattern 3a is formed by a plurality of slits extending through the rotating plate 3. These slits may be hollow or may contain transparent glass.

[0025] The fixed plate 4 is fixed at a position opposite the rotating plate 3. The fixed plate 4 is formed, for example, into a rectangular plate shape and is arranged parallel to the rotating plate 3. The fixed plate 4 has a light transmission pattern 4a formed so as to be located on a straight line connecting the light source 5 and the light transmission pattern 3a of the rotating plate 3. The light transmission pattern 4a is formed by a plurality of slits extending through the fixed plate 4. In this embodiment, five slits are arranged along the radial direction of the rotating plate 3. These slits may be voids or may be provided with transparent glass portions.

[0026] The light source 5 is a light emitting element such as an LED (Light Emitting Diode). The light source 5 is fixed to the opposite side of the rotating plate 3 relative to the fixed plate 4 and emits light toward the rotating plate 3. The light receiving module 6 is fixed to the opposite side of the rotating plate 3 and the fixed plate 4 relative to the light source 5. The light receiving module 6 has a plurality of light receiving surfaces 21a ( Figure 2 and Figure 3 ) to detect the light incident on each light receiving surface 21a.

[0027] In encoder 1, if the light transmission pattern 3a of rotating plate 3 and the light transmission pattern 4a of fixed plate 4 overlap on a straight line connecting light source 5 and light receiving surface 21a of light receiving module 6, light from light source 5 passes through rotating plate 3 and fixed plate 4 and is incident on light receiving surface 21a. On the other hand, if the light transmission pattern 3a and light transmission pattern 4a do not overlap, light from light source 5 is blocked by rotating plate 3 and does not enter light receiving surface 21a. Processing unit 7, such as a signal processing circuit, encodes the light detection results of each light receiving surface 21a and outputs Gray codes G0, G1, G2, G3, and G4 representing the absolute value of the rotation angle of rotating shaft 2.

[0028] Next, the structure of the light receiving module 6 will be further described. Figure 2 and Figure 3 As shown, the light receiving module 6 includes a support 11 , a light receiving element 12 , an optical fiber plate (hereinafter also referred to as “FOP (Fiber Optic Plate)”) 13 , a lead wire 14 , and a resin member 15 .

[0029] The support body 11 is a substantially rectangular parallelepiped box with one side open, and includes a rectangular plate-shaped bottom wall portion 16 and a side wall portion 17 disposed on one side S of the bottom wall portion 16. The side wall portion 17 is provided along the outer edge of the bottom wall portion 16 and has a rectangular ring shape when viewed from the side S. The support body 11 is formed by laminating the bottom wall portion 16 and the side wall portion 17, both of which are made of glass epoxy resin.

[0030] A plurality of wirings 18 for outputting signals from the light receiving module 6 to the outside are provided on the bottom wall 16. The wirings 18 are exposed on a main surface 16a on one side S of the bottom wall 16, a main surface 16b opposite the main surface 16a, and a side surface 16c connecting the main surfaces 16a and 16b.

[0031] The light receiving element 12 is a rectangular plate-shaped light receiving chip and has a plurality of light receiving parts 21. The light receiving part 21 is, for example, a photodiode or a photodiode array, and has a light receiving surface 21a on one side 12a of the light receiving element 12. The light receiving element 12 is arranged (fixed) on the bottom wall portion 16 in such a manner that the light receiving surface 21a faces one side S. The light receiving element 12 is surrounded by the side wall portion 17 when viewed from the one side S. A plurality of terminals 19 for outputting signals from the light receiving part 21 are provided on one side 12a of the light receiving element 12. In one side 12a, each light receiving surface 21a is arranged in an area on the central side, and each terminal 19 is arranged outside the area.

[0032] FOP13 is an optical device formed by bundling multiple (large) optical fibers. For example, FOP13 contains tens of millions of optical fibers with diameters ranging from several nm to tens of nm. FOP13 is, for example, in the shape of a rectangular parallelepiped, and has an input surface 13a and an output surface 13b that are opposite to each other. The input surface 13a is formed by one end surface of the multiple optical fibers, and the output surface 13b is formed by the other end surface of the multiple optical fibers. FOP13 is arranged on the light receiving element 12 in such a manner that the output surface 13b is opposite to the light receiving surface 21a of the light receiving portion 21. In more detail, the output surface 13b is opposite to the central side area of one surface 12a where the light receiving surface 21a is arranged.

[0033] In FOP 13, light incident on input surface 13a propagates within the optical fiber and is output from output surface 13b. More specifically, light incident on a certain position on input surface 13a is emitted from a corresponding position on output surface 13b. Therefore, by placing FOP 13 above light-receiving element 12, light incident on input surface 13a is not diffused and is reliably guided to light-receiving surface 21a.

[0034] Wire 14 is a bonding wire that electrically connects wiring 18 and terminal 19 inside side wall portion 17. One end of wire 14 is bonded to an exposed portion of wiring 18 on the main surface 16a side, and the other end is bonded to terminal 19. The middle portion of wire 14 is bent so as to bulge toward one side S.

[0035] The resin member 15 is disposed on the bottom wall 16 on the inner side of the side wall 17. The resin member 15 covers the exposed portion of the main surface 16a side of the wiring 18, the terminal 19, and the lead wire 14. The resin member 15 is bonded to the main surface 16a of the bottom wall 16, the inner surface 17a of the side wall 17, the first surface 12a and the side surface 12b of the light receiving element 12, and the side surface 13c of the FOP 13. When viewed from one side S, the resin member 15 has a rectangular ring shape surrounding the FOP 13.

[0036] Furthermore, the resin member 15 is inserted between (interposed between) the one surface 12a of the light-receiving element 12 and the output surface 13b of the FOP 13, thereby fixing the FOP 13 to the light-receiving element 12. The resin member 15 is formed by potting a transparent resin such as silicone resin, for example. During this potting, the resin material injected onto the main surface 16a of the bottom wall portion 16 before curing is blocked by the inner surface 17a of the side wall portion 17.

[0037] Here, refer to Figure 3 The positional relationship of the various components when viewed from the direction along the main surface 16a of the bottom wall portion 16 will be described. The end surface 17b on one side S of the side wall portion 17 is located closer to the one side S than the light-receiving surface 21a (one side 12a) of the light-receiving element 12, and the input surface 13a is located closer to the one side S than the end surface 17b. Furthermore, the end surface 17b is located closer to the one side S than the lead 14, and the input surface 13a is located closer to the one side S than the resin member 15. In this embodiment, the end surface 17b, the light-receiving surface 21a, and the input surface 13a are parallel to each other.

[0038] The light receiving module 6, constructed as described above, is fixed to a position where the input surface 13a of the FOP 13 and the light transmission pattern 3a of the rotating plate 3 are opposite and close to each other. As described above, if the light transmission pattern 3a of the rotating plate 3 and the light transmission pattern 4a of the fixed plate 4 overlap on the straight line connecting the light source 5 and the light receiving surface 21a, light from the light source 5 passes through the rotating plate 3 and the fixed plate 4. Light passing through the rotating plate 3 and the fixed plate 4 is incident on the input surface 13a, guided by the FOP 13, and incident on the light receiving surface 21a. As a result, light is detected on each light receiving surface 21a.

[0039] As described above, in the light receiving module 6, the end face 17b of the side wall portion 17 is located closer to one side S than the light receiving surface 21a of the light receiving element 12. Thus, for example, the light receiving element 12 can be reliably protected from physical contact. In addition, the FOP 13 is arranged on the light receiving element 12 in such a manner that the output face 13b is opposite to the light receiving surface 21a. Thus, light incident on the input face 13a can be reliably guided to the light receiving surface 21a. Furthermore, the input face 13a of the FOP 13 is located closer to one side S than the end face 17b of the side wall portion 17. Thus, the input face 13a can be brought closer to the light passing pattern 3a of the encoder 1. As a result, the diffusion of light passing through the light passing pattern 3a and its incidence on the light receiving surface 21a can be suppressed. Therefore, according to the light receiving module 6, while protecting the light receiving element 12, good detection accuracy can be obtained when applied to the encoder 1.

[0040] As in the aforementioned conventional encoder, when the light receiving surface 21a of the light receiving element 12 cannot be brought close to the light transmission pattern 3a, a method for suppressing the diffusion of light passing through the light transmission pattern 3a and its incidence on the light receiving surface 21a may involve using a light source 5 that emits light with high parallelism. In contrast, in the light receiving module 6, since the input surface 13a is brought close to the light transmission pattern 3a, the diffusion of light passing through the light transmission pattern 3a and its incidence on the light receiving surface 21a can be suppressed, the use of a light source 5 that emits light with high parallelism is not necessarily required. This increases the degree of freedom in selecting the light source 5.

[0041] The light receiving module 6 further includes a lead wire connected to the wiring 18 and the terminal 19, and a resin member 15 covering the wiring 18, the terminal 19, and the wire 14. Furthermore, the end surface 17b of the side wall 17 is located closer to the side S than the wire 14, and the input surface 13a is located closer to the side S than the resin member 15. Thus, since the wiring 18, the terminal 19, and the wire 14 are covered by the resin member 15, they are protected from oil and other substances that may be scattered during use of the encoder 1. Furthermore, since the end surface 17b of the side wall 17 is located closer to the side S than the wire 14, external forces acting on the wire 14 are suppressed. Furthermore, the input surface 13a can be brought closer to the light transmission pattern 3a of the encoder 1 without being obstructed by the resin member 15.

[0042] In the light receiving module 6, the FOP 13 is fixed to the light receiving element 12 via the resin member 15. This can omit a structure for fixing the FOP 13 to the light receiving element 12, thereby simplifying the structure.

[0043] While the embodiments of one aspect of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the materials and shapes of the components are not limited to the above-described materials and shapes, and various materials and shapes can be used.

[0044] In the encoder 1 of the above embodiment, the fixed plate 4 can be omitted. In this case, the light receiving module 6 is arranged so that the input surface 13a of the FOP 13 faces the light passing pattern 3a of the rotating plate 3. When the fixed plate 4 is omitted, the light receiving module 6 can be arranged as follows. Figure 4The light-receiving module 6 is constructed as shown in the variation. In this variation, the light-receiving module 6 further includes a light-shielding layer 23 disposed between the light-receiving surface 21a of the light-receiving element 12 and the output surface 13b of the FOP 13. The light-shielding layer 23 is provided on the light-receiving surface 21a. More specifically, the light-shielding layer 23 is provided in an area opposite to the output surface 13b on one side 12a of the light-receiving element 12. The light-shielding layer 23 has a light-passing pattern formed at a position corresponding to the light-passing pattern 4a of the fixing plate 4, and blocks light from the light source 5 in a portion other than the light-passing pattern. The light-passing pattern is formed, for example, by removing a portion of the light-shielding layer 23 by patterning.

[0045] Through this variation, as in the above-described embodiment, it is possible to achieve good detection accuracy while protecting the light-receiving element 12. Furthermore, the light passing through the light-passing pattern 3a of the rotating plate 3 can be appropriately incident on the light-receiving surface 21a. Furthermore, because the light-passing pattern of the light-shielding layer 23 is closer to the light-receiving surface 21a, the positional accuracy between the light-passing pattern of the light-shielding layer 23 and the light-receiving surface 21a can be improved. Furthermore, because the light-passing pattern of the light-shielding layer 23 and the light-receiving surface 21a are imaged to the input surface 13a via the output surface 13b, the light-passing pattern of the light-shielding layer 23 and the light-receiving surface 21a can be optically close to the light-passing pattern of the rotating plate 3. As a result, the detection accuracy in the case of the encoder 1 is further improved. Furthermore, in the above-described variation, the light-shielding layer 23 can also be provided on the output surface 13b of the FOP 13. The light-shielding layer 23 can also be provided on the input surface 13a of the FOP 13. In FOP 13, light incident on a certain position on input surface 13a propagates within the optical fiber and exits from a position corresponding to that position on output surface 13b. Therefore, light passing through light-shielding layer 23 on input surface 13a enters a certain position on input surface 13a, exits from a position corresponding to that position on output surface 13b, and enters light-receiving surface 21a of light-receiving element 12, thereby achieving substantially the same effect as when light-shielding layer 23 is formed on light-receiving surface 21a.

[0046] In the encoder 1 of the above embodiment, the light source 5, fixed plate 4, rotating plate 3, and light receiving module 6 are arranged in this order. However, the light source 5, rotating plate 3, fixed plate 4, and light receiving module 6 may also be arranged in this order. In this case, the light receiving module 6 is arranged so that the input surface 13a of the FOP 13 faces the light transmission pattern 4a of the fixed plate 4. With this variation, as in the above embodiment, light that has passed through the light transmission pattern 4a can be prevented from diffusing and entering the light receiving surface 21a. Furthermore, it is possible to achieve good detection accuracy while protecting the light receiving element 12.

[0047] In the above embodiment, the lead wire 14 can be omitted. For example, the wiring 18 can be provided on the main surface 16a of the bottom wall portion 16, facing the back surface of the light receiving element 12, and the terminal 19 can be provided on the back surface of the light receiving element 12. The wiring 18 and the terminal 19 can be connected on the back surface of the light receiving element 12. In this case, the resin member 15 can also be omitted. The FOP 13 can also be fixed to the light receiving element 12 by an adhesive or the like instead of the resin member 15. The encoder according to one aspect of the present invention can also be applied to an incremental encoder.

[0048]

Explanation of symbols

[0049] 1 Encoder

[0050] 3 Rotating Plate

[0051] 5 Light Source

[0052] 6 Light receiving module

[0053] 11 Support

[0054] 12 Light receiving element

[0055] 13 Fiber Optic Board

[0056] 13a Input side

[0057] 13b Output side

[0058] 14 wires

[0059] 15 Resin components

[0060] 16 bottom wall

[0061] 17 Side wall

[0062] 18 Wiring

[0063] 19 terminals

[0064] 21a Light-receiving surface

[0065] 23 Shading layer.

Claims

1. A light receiving module for an encoder, comprising: a support having a bottom wall portion and a side wall portion disposed on a main surface of the bottom wall portion on one side of the bottom wall portion; a light receiving element having a light receiving surface, fixed to the bottom wall portion with the light receiving surface facing the one side and surrounded by the side wall portion when viewed from the one side; and an optical fiber plate having an input surface formed by one end surface of a plurality of optical fibers and an output surface formed by the other end surfaces of the plurality of optical fibers, and being arranged on the light receiving element in such a manner that the output surface faces the light receiving surface; When viewed in a direction along the main surface of the bottom wall, the end surface on the one side of the side wall is located closer to the one side than the light receiving surface, and the input surface is located closer to the one side than the end surface.

2. The light receiving module for an encoder according to claim 1, wherein Further possess: a lead wire connected to a wiring provided on the bottom wall portion and a terminal provided on the light receiving element on the inner side of the side wall portion; and a resin member disposed on the bottom wall portion on the inner side of the side wall portion and covering the wiring, the terminal, and the lead wire; The end surface is located closer to the one side than the lead wire, and the input surface is located closer to the one side than the resin member.

3. The light receiving module for an encoder according to claim 2, wherein: The optical fiber plate is fixed to the light receiving element via the resin member.

4. The light receiving module for an encoder according to any one of claims 1 to 3, wherein Further possess: The light shielding layer has a light passing pattern and is disposed between the light receiving surface and the output surface.

5. An encoder comprising: a rotating plate having a light-passing pattern; a light source disposed on one side relative to the rotating plate; and The encoder light receiving module according to any one of claims 1 to 4, which is arranged on the other side relative to the rotating plate.

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