Encoder

Abstract

The purpose of the present invention is to obtain an encoder that can be reduced in size in the thickness direction. This encoder comprises a rotary slit disk in which a slit is formed, a light projection element that projects projection light toward the rotary slit disk, a light reception element that receives reflected light resulting from the projection light hitting and being reflected by the rotary slit disk, and a substrate, the substrate having a transmission part through which the projection light and the reflected light are transmitted, and the transmission part being disposed between the rotary slit disk and the light projection element and light reception element. Therefore, it is possible to reduce the size in the thickness direction, which is the direction along the center axis.

Description

Encoder

[0001] The present disclosure relates to an encoder.

[0002] Conventionally, a reflective optical encoder is known in which a light projecting unit and a light receiving unit are attached to a surface facing a circular scale plate of a substrate to receive the light irradiated on the scale plate (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-000658

[0004] In a conventional reflective optical encoder, the light irradiated from the light projecting unit toward the scale plate is first reflected by the scale plate, then hits the light receiving element of the light receiving unit, and finally is received by the light receiving element. At this time, in order for the reflected light to hit the light receiving element uniformly over a wide range, it is necessary to appropriately set the distance between the scale plate and the light receiving element of the light receiving unit.

[0005] The distance between the scale plate and the light receiving element of the light receiving unit is set by appropriately setting it in the thickness direction of the encoder, that is, by appropriately adjusting the distance in the direction along the rotation axis of a rotating body such as the rotation axis of the motor to which the encoder is attached. Also, a reflective optical encoder needs to set a wider distance between the scale plate and the light receiving element of the light receiving unit compared to a transmissive optical encoder. For this reason, there has been a problem that the encoder cannot be miniaturized.

[0006] An object of the present disclosure is to provide an encoder that can be miniaturized in the thickness direction in order to solve the above problems.

[0007] The encoder according to the present disclosure includes a rotating slit plate in which slits are formed, a light projecting element that projects light as projection light toward the rotating slit plate, a light receiving element that receives the reflected light when the projection light hits the rotating slit plate and is reflected, and a substrate that supports the light projecting element and the light receiving element. The substrate has a transmission portion through which each of the projection light and the reflected light passes, and the transmission portion is disposed between the light projecting element and the light receiving element and the rotating slit plate.

[0008] According to the encoder according to the present disclosure, it can be miniaturized in the thickness direction.

[0009] This is a schematic diagram showing an encoder according to Embodiment 1. This is a schematic diagram showing a conventional encoder. This is a schematic diagram showing an encoder equipped with a light-emitting element and a light-receiving element according to a modification of Embodiment 1.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Embodiment 1. Figure 1 is a schematic diagram showing an encoder 1 according to Embodiment 1. The encoder 1 is attached to a rotating member and detects the rotation angle of the member.

[0011] The encoder 1 comprises a main body (not shown), a rotating slit plate 10 supported by the main body, a light-emitting and receiving element 20, and a substrate 50 supporting the light-emitting and receiving element 20.

[0012] The rotary slitting plate 10 is a disc-shaped, plate-like component. The rotary slitting plate 10 is rotatably supported by a main body (not shown). The rotary slitting plate 10 can rotate about its central axis L.

[0013] Slits are formed on the surface of the plate-shaped rotary slitting disc 10. The surface of the rotary slitting disc 10 on which the slits are formed is a plane perpendicular to the central axis L.

[0014] Specifically, the slits are multiple through-holes. Each hole is arranged at equal intervals along the circumferential direction of the rotating slitting disc 10. That is, light projected onto the rotating slitting disc 10 is not reflected at each hole.

[0015] On the other hand, projected light is reflected at a specific angle from the surface of the rotating slitting plate 10 located between each hole. In this way, the rotating slitting plate 10 has alternating areas that reflect light and areas that do not.

[0016] Furthermore, each hole serving as a slit does not necessarily have to be a physically penetrating hole. For example, instead of holes, the surface of the rotating slitting plate 10 at the corresponding location may be roughened. Light projected onto the roughened surface may be diffused and not reflected, or even if reflected at a specific location, the intensity of the reflected light may be below a certain threshold and not be considered reflected.

[0017] A rotating object, or rotating body, is connected to the rotary slitting plate 10. Examples of rotating bodies include the output shaft of a motor or a rotating shaft. The rotary slitting plate 10 and the rotating body are connected such that the axis of rotation of the rotating body and the central axis L of the rotary slitting plate 10 are on the same line.

[0018] The light-emitting and receiving element 20 projects light toward a specific location. The light-emitting and receiving element 20 also detects the incident light and outputs a signal to the outside indicating that light has been received.

[0019] The substrate 50 is supported by a main body (not shown). The substrate 50 is plate-shaped. One surface of the substrate 50 is called the first surface 50a, and the surface opposite to the first surface 50a is called the second surface 50b.

[0020] The first surface 50a of the substrate 50 is mounted with a light-emitting / receiving element 20, power supply-related equipment (not shown), and computing-related equipment (not shown), and wiring connecting these devices is formed thereon. Similarly, the second surface 50b of the substrate 50 may also be mounted with equipment (not shown) or have wiring formed thereon.

[0021] For example, the computing-related equipment mounted on the circuit board 50 may perform various calculations based on the signal output by the light-emitting / receiving element 20 indicating that it has received light. Alternatively, the light-emitting / receiving element 20 may have a computing function and perform various calculations itself, outputting the calculation results.

[0022] A transparent portion 51 is formed in the substrate 50. The transparent portion 51 is a through hole formed in the substrate 50. Light projected from the light-emitting / receiving element 20 and light incident on the light-emitting / receiving element 20 pass through the transparent portion 51.

[0023] Next, the arrangement of each element constituting the encoder 1 will be described. The substrate 50 is positioned so as to face the surface of the rotating slitting plate 10 on which the slits are formed. At this time, the substrate 50 is supported such that its second surface 50b faces the rotating slitting plate 10.

[0024] The light-emitting and receiving element 20 is mounted and supported on the first surface 50a so as to cover the transmissive portion 51. That is, the light-emitting and receiving element 20 is supported on the substrate 50 such that the transmissive portion 51 is positioned between it and the rotating slit plate 10. The light-emitting and receiving element 20 projects light through the transmissive portion 51 toward the surface of the rotating slit plate 10 where the slits are formed. At this time, the light projected toward the surface of the rotating slit plate 10 is called projected light L20.

[0025] The projected light L20 is reflected by the surface of the rotating slit plate 10. At this time, the reflected light is called reflected light L25. The reflected light L25 passes through the transmission section 51 and heads towards the light-transmitting element 20, and is incident on the light-transmitting element 20. The light-transmitting element 20 receives the incident reflected light L25.

[0026] In this manner, the light-emitting and receiving element 20, the light-transmitting section 51, and the rotating slit plate 10 are arranged such that light emitted from the light-emitting and receiving element 20 is reflected by the rotating slit plate 10 and then incident back onto the light-emitting and receiving element 20.

[0027] When the light-emitting / receiving element 20 detects the incidence of reflected light L25, that is, when it receives light, the light-emitting / receiving element 20 outputs a signal indicating that reflected light L25 has been incident. When the rotating slitting plate 10 rotates around the central axis L due to the rotation of the rotating body, the light-emitting / receiving element 20 alternately repeats a state in which it receives reflected light L25 and a state in which it does not receive reflected light L25 in accordance with the rotation of the rotating slitting plate 10, due to the slits formed in the rotating slitting plate 10.

[0028] The light-emitting and receiving element 20 sequentially outputs signals to the outside indicating that it has received reflected light L25 based on this state. A calculation device (not shown) calculates the rotational status of the rotating body, such as the direction of rotation, amount of rotation, and rotational speed, based on the signals output by the light-emitting and receiving element 20 indicating that it has received reflected light L25. Alternatively, the light-emitting and receiving element 20 may have a calculation function and calculate the rotational status of the rotating body itself.

[0029] A specific distance is required for the projected light L20 projected from the light-emitting / receiving element 20 to be reflected by the rotating slitting plate 10 and reach the light-emitting / receiving element 20 as reflected light L25. That is, a specific distance X is required between the light-emitting / receiving element 20 and the surface of the rotating slitting plate 10.

[0030] Here, in order to compare the encoder 1 according to Embodiment 1, a comparative encoder 90 will be described. Figure 2 is a perspective view showing a conventional encoder 90.

[0031] In the conventional encoder 90, the light-emitting and receiving element 20 is mounted and positioned on the second surface 50b of the substrate 50. The substrate 50 does not have a transparent portion 51. The other components of the conventional encoder 90 are the same as the other components of the encoder 1 according to Embodiment 1, so a description is omitted.

[0032] The light-emitting and receiving element 20 of the encoder 90 is mounted on the second surface 50b. In both the conventional encoder 90 and the encoder 1 according to Embodiment 1, if the performance of the light-emitting and receiving element 20 is the same as the state of the surface on which the slits of the rotating slitting disc 10 are formed, then in the conventional encoder 90, as in the encoder 1 according to Embodiment 1, a specific distance X is required between the light-emitting and receiving element 20 and the surface of the rotating slitting disc 10.

[0033] Therefore, considering distance X, the distance from the surface of the rotating slitting plate 10 to the upper end of the equipment mounted and supported on the first surface 50a of the substrate 50 is distance H90.

[0034] Returning to Figure 1, let's continue the explanation. In the encoder 1 according to Embodiment 1, the light-emitting and receiving element 20 is mounted on the first surface 50a. Considering the distance X between the light-emitting and receiving element 20 and the surface of the rotating slitting plate 10, the distance from the surface of the rotating slitting plate 10 to the upper end of the device mounted and supported on the first surface 50a of the substrate 50 is distance H1.

[0035] In the encoder 1 according to Embodiment 1, the distance X is set to include the thickness of the substrate 50, so as can be seen in Figures 1 and 2, the distance H1 is smaller than the distance H90.

[0036] In this embodiment 1, the encoder 1 includes a light-emitting and light-receiving element 20. However, it is not limited to this. The light-emitting and light-receiving element 20 may be replaced with another element consisting of a light-emitting element 30 and a light-receiving element 35. Figure 3 is a schematic diagram showing an encoder 1 equipped with a light-emitting element 30 and a light-receiving element 35 according to a modification of embodiment 1. The light-emitting element 30 projects light toward a specific location. The light-receiving element 35 detects the incident light and outputs a signal to the outside indicating that light has been received. In this case, in the light-emitting and light-receiving element 20 described in embodiment 1 above, the light-emitting element 30 has a function and configuration based on irradiating light, and the light-receiving element 35 has a function and configuration when receiving light and when light has been received. That is, the light-emitting and light-receiving element 20 is an integrated unit of the light-emitting element 30 and the light-receiving element 35.

[0037] Furthermore, the transparent portion 51 in Embodiment 1 is a through hole. However, it is not limited to this. For example, it may be a notch cut out including the outer periphery of the substrate 50. That is, it may be a space that does not obstruct the projected light L20 and the reflected light L25. Moreover, the transparent portion 51 can have any configuration as long as the projected light L20 passes through the transparent portion 51, and then the reflected light L25 passes through the transparent portion 51 and the reflected light L25 has an intensity above a certain threshold and can be detected by the light-receiving element 35. The transparent portion 51 may be formed using a transparent material such as transparent acrylic resin or transparent glass instead of a space. Moreover, the substrate 50 including the transparent portion 51 may be constructed using a transparent material such as transparent acrylic resin or transparent glass. In this case, it is preferable to use a colorless and transparent material, but the color of the transparent material is not particularly specified as long as the light-receiving element 35 can receive the reflected light L25.

[0038] The encoder 1 according to Embodiment 1 includes a rotating slitting plate 10 with slits formed therein. The encoder 1 further includes a light-emitting element 30 that projects light as projected light L20 toward the rotating slitting plate 10, and a light-receiving element 35 that receives reflected light L25 that is reflected when the projected light L20 strikes the rotating slitting plate 10. The encoder 1 further includes a substrate 50 that supports the light-emitting element 30 and the light-receiving element 35. The substrate 50 also has a transmissive portion 51 through which the projected light L20 and the reflected light L25 are transmitted. Furthermore, the transmissive portion 51 is arranged between the light-emitting element 30 and the light-receiving element 35 and the rotating slitting plate 10. This allows the distance X between the light-emitting element 30 and the light-receiving element 35 and the rotating slitting plate 10 to be set, including the thickness of the substrate 50. Therefore, the size in the direction along the central axis L of the rotating slitting plate 10 can be reduced, and the internal space of the encoder 1 can be effectively utilized. Therefore, the encoder 1 can be miniaturized in the thickness direction, which is along the central axis L.

[0039] The transparent portion 51 of the encoder 1 according to Embodiment 1 is a space formed in the substrate 50. This eliminates the need for any special processing other than the processing required to create the space in the substrate 50. Therefore, the manufacturing cost of the encoder 1 can be reduced.

[0040] The transparent portion 51 of the encoder 1 according to Embodiment 1 is a through-hole formed in the substrate 50. This allows the transparent portion 51 to be formed using a well-known drilling process. Therefore, the manufacturing cost of the encoder 1 can be reduced.

[0041] The transparent portion 51 of the encoder 1 according to Embodiment 1 is a notch formed in the substrate 50. This allows the transparent portion 51 to be formed using a well-known cutting process. Therefore, the manufacturing cost of the encoder 1 can be reduced.

[0042] The transparent portion 51 of the encoder 1 according to Embodiment 1 is made of a transparent material. This allows the light-emitting element 30 and the light-receiving element 35 to be protected by the transparent portion 51. Therefore, a more reliable encoder 1 can be obtained.

[0043] The substrate 50 of the encoder 1 according to Embodiment 1 is made of a transparent material including the transmission part 51. Thereby, it becomes unnecessary to process and form the transmission part 51 on the substrate 50. Therefore, the manufacturing cost of the encoder 1 can be suppressed. Further, thereby, the light projecting element 30 and the light receiving element 35 can be protected by the transmission part 51. Therefore, an encoder 1 that is less likely to fail can be obtained.

[0044] The light projecting element 30 and the light receiving element 35 of the encoder 1 according to Embodiment 1 are a light projecting / receiving element 20 integrated with each other. Thereby, arranging the light projecting element 30 and the light receiving element 35 on the substrate 50 becomes arranging one light projecting / receiving element 20 on the substrate 50. Therefore, the manufacturing cost of the encoder 1 can be suppressed.

[0045] 1 Encoder, 10 Rotating slit plate, 20 Light projecting / receiving element, 30 Light projecting element, 35 Light receiving element, 50 Substrate, 50a First surface, 50b Second surface, 51 Transmission part, 90 Encoder, H1 Distance, H90 Distance, L Central axis, L20 Projected light, L25 Reflected light, X Distance.

Claims

1. An encoder (1) comprising: a rotating slitting plate (10) having slits formed therein; a light-emitting element (30) that projects light as projected light (L20) toward the rotating slitting plate (10); a light-receiving element (35) that receives reflected light (L25) that is reflected when the projected light (L20) strikes the rotating slitting plate (10); and a substrate (50) that supports the light-emitting element (30) and the light-receiving element (35), wherein the substrate (50) has a transmissive portion (51) through which the projected light (L20) and the reflected light (L25) respectively are transmitted, and the transmissive portion (51) is arranged between the light-emitting element (30) and the light-receiving element (35) and the rotating slitting plate (10).

2. The encoder (1) according to claim 1, wherein the transparent portion (51) is a space formed in the substrate (50).

3. The encoder (1) according to claim 2, wherein the transparent portion (51) is a through hole formed in the substrate (50).

4. The encoder (1) according to claim 2, wherein the transparent portion (51) is a notch formed in the substrate (50).

5. The encoder (1) according to claim 1, wherein the transparent portion (51) is made of a transparent material.

6. The encoder (1) according to claim 1, wherein the substrate (50), including the transparent portion (51), is made of a transparent material.

7. The encoder (1) according to any one of claims 1 to 6, wherein the light-emitting element (30) and the light-receiving element (35) are a light-emitting and light-receiving element (20) that is integrated with each other.

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