Fiber sensor

Abstract

To provide a fiber sensor that can suppress the intrusion of external light into a light-receiving element used to monitor the amount of light emitted by a light-emitting element, thereby achieving miniaturization and high optical coupling.SOLUTION: A fiber sensor includes a substrate, a light-emitting element mounted on the substrate and projecting light onto a fiber, a light-receiving element mounted on the substrate and monitoring the amount of light emitted by the light-emitting element, and a fiber holding component holding the fiber. The fiber holding component includes a hole into which the fiber is inserted, an opening located between the light-emitting element and the hole, and a light-shielding portion located radially outward of the opening and between the light-receiving element and the hole.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a fiber optic sensor.

Background Art

[0002] A fiber optic sensor is a sensor for connecting various fibers to a device such as a fiber amplifier and using them. The fiber optic sensor includes a hole for inserting a fiber, a light emitting element that projects light onto the end face of the inserted fiber, and a monitoring light receiving element that monitors the amount of light emitted by the light emitting element. By the monitoring light receiving element monitoring whether the light emitting element maintains an appropriate amount of light emission, the fiber optic sensor can transmit an appropriate signal.

[0003] Patent Document 1 discloses a photoelectric sensor as a fiber optic sensor. The light projecting member of the photoelectric sensor includes a light emitting element, a monitoring light receiving element, and a reflector. The monitoring light receiving element detects the amount of light emitted by the light emitting element, and feedback control of the light emitting element is performed so that the detected amount of light emission becomes a predetermined value.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The reflector is provided between the light-emitting element and the end face of the fiber, and serves to guide the light from the light-emitting element to the fiber. A predetermined distance is ensured between the light-emitting element and the end face of the fiber. In order to miniaturize the entire device and improve the optical coupling rate, it is desired to bring the end face of the fiber closer to the light-emitting element. However, if it is brought too close, unintended disturbing light such as reflected light from the end face of the fiber may enter the light-receiving element for monitoring, and there is a risk that the correct light emission amount cannot be monitored. For example, an unintended feedback that attempts to reduce the luminance of the light-emitting element may occur, making stable sensing difficult.

[0006] The present disclosure provides an optical fiber sensor capable of suppressing the incidence of disturbing light on a light-receiving element for monitoring the light emission amount of a light-emitting element and realizing miniaturization and high optical coupling.

Means for Solving the Problems

[0007] One aspect of the present disclosure includes a substrate, a light-emitting element mounted on the substrate that projects light onto an optical fiber, a light-receiving element mounted on the substrate that monitors the light emission amount of the light-emitting element, and an optical fiber holding component that holds the optical fiber. The optical fiber holding component includes a hole into which the optical fiber is inserted, an opening located between the light-emitting element and the hole, and a light-shielding portion located radially outside the opening and between the light-receiving element and the hole, and is an optical fiber sensor.

Effects of the Invention

[0008] According to the present disclosure, it is possible to suppress the incidence of disturbing light on a light-receiving element for monitoring the light emission amount of a light-emitting element and realize miniaturization and high optical coupling.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, a detailed description of well-known matters and a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and it is not intended to limit the subject matter described in the claims thereby.

[0011] FIG. 1 is a perspective view of a fiber sensor 1 according to an embodiment of the present disclosure.

[0012] The fiber sensor 1 has a thin box shape and is provided with holes 62 and 70 on one side surface into which fibers to be described later are inserted. The fiber sensor 1 is configured to connect fibers corresponding to the light emitting unit and the light receiving unit respectively, and to arrange the tips of the light emitting unit and the light receiving unit at positions where the object to be detected can be detected. In this example, the emitted light from the light emitting unit propagates through the fiber connected to the hole 62 and is emitted from the other end of the fiber. The reflected light reflected by the object to be detected propagates through the fiber connected to the hole 70 and is incident on the light receiving unit. The light incident on the photoelectric conversion element of the light receiving unit is converted into an electrical signal and amplified by a light receiving amplifier. Then, for example, the fiber sensor 1 compares this electrical signal with a predetermined threshold value in a comparison circuit to determine the presence or absence of the object to be detected, measures the amount of received light, or performs processing based on the amount of received light. The determination result of the presence or absence of the object to be detected, the measurement result of the amount of received light, or the processing result based on the amount of received light, etc. may be output to a PLC (Programmable Logic Controller) device or the like.

[0013] In addition, a coordinate including the X-axis along the longitudinal side of the fiber sensor 1, the Y-axis along the width direction of the fiber sensor 1, and the Z-axis along the height direction of the fiber sensor 1 is defined and utilized in the following description. Also, the positive side of the Z-axis is also referred to as "up", and the negative side of the Z-axis is also referred to as "down".

[0014] FIG. 2 is a perspective view of the fiber sensor, (A) is a perspective view of the finished product, and (B) is an exploded perspective view. FIG. 3 is a perspective view of the fiber holding component. FIG. 4 is a perspective view of the fiber holding component seen from the side of the light emitting module and is an enlarged view of part B in FIG. 2(B). FIG. 5 is a perspective view of the fiber holding component seen from the side of the hole into which the fiber is inserted.

[0015] As shown in Fig. 2(B), the fiber optic sensor 1 includes a main body 10 and a fiber holding component 50. The main body 10 is mainly a part for generating or processing electrical signals, etc. The main body 10 includes a first case 21, a second case 22, an indicator 23, a display cover 24, a cover 25, a NET (Network) lens 26, a rail stopper 27, a display 28, a shield board 29, a screw 30, a PCB (Printed Circuit Board) substrate (substrate) 31, a pin header 32, and a resin cable 33.

[0016] As shown in Fig. 3 etc., the fiber holding component 50 is an integrated module component. Fig. 4 is also an enlarged view of part B in Fig. 2(B). As shown in Figs. 4 and 5, the fiber holding component 50 includes a main block 51, a clamp member 52, and a clamp lever 53. Note that the perspective view of Fig. 3 shows a state where the clamp lever 53, the light emitting module 54, and the light receiving module 55 are removed.

[0017] The main block 51 is the main component of the fiber holding component 50, and an insertion hole 62A that constitutes a part of the hole 62 is formed inside. Also, it includes a hole for incorporating the fiber holding component 50 into the first case 21. The fiber holding component 50 press-fits this hole onto the convex portion of the first case 21 for positioning. The clamp member 52 serves as a lid for one side surface of the fiber optic sensor 1 when attached to the main body 10. An insertion hole 62B that constitutes a part of the hole 62 is formed inside the clamp member 52. When the main block 51 and the clamp member 52 are combined, the insertion hole 62A and the insertion hole 62B are connected to form the hole 62. As shown in Fig. 1, the hole 62 is exposed from one side surface of the fiber optic sensor 1 constituted by the clamp member 52. The main block 51 is made of, for example, conductive resin.

[0018] The clamp lever 53 is provided at one end of the main block 51. The clamp lever 53 is an operating lever for locking the fiber after it is inserted into the holes 62 and 70. With the clamp lever 53 in the open state (unlocked state), the fiber is inserted into the holes 62 and 70. With the clamp lever 53 in the closed state (locked state), it is fixed to the fiber by pressing friction and cannot be removed from the holes 62 and 70.

[0019] The light emitting module 54 functions as a light emitting unit that emits light to the fiber connected to the hole 62. As shown in FIG. 5, the light emitting module 54 includes a lens 57 and an LED (Light Emitting Diode) 58 as a light emitting element serving as a light source. The lens 57 is provided at a substantially central portion of the light emitting module 54 by molding a mold portion 56 made of a light emitting resin. Since the mold portion 56 has a portion in the shape of the lens 57, light can be condensed and highly coupled. The LED 58 is mounted on the PCB substrate 31 by soldering or the like and is electrically connected to the light emitting module 54 by a wire or the like. The light receiving module 55 functions as a light receiving unit that receives light from the fiber connected to another hole 70 provided in the fiber holding component 50.

[0020] FIG. 6 is an enlarged cross-sectional view in the XZ plane of part A in FIG. 1, and FIG. 7 is a perspective view showing a part of FIG. 6. The connection mode between the fiber holding component 50 and the fiber will be described in detail with reference to FIGS. 6 and 7.

[0021] As shown by the dashed line in FIG. 6, the first fiber 101 or the second fiber 102 as the fiber is inserted to the innermost part of the hole 62 (the innermost part in the X-axis direction, the positive-side end). The first fiber 101 and the second fiber 102 are flexible. The first fiber 101 and the second fiber 102 have different diameters (described later). The tip of the first fiber 101 or the second fiber 102 faces the lens 57 of the light projecting module 54 at the innermost part of the hole 62. An LED 58 is provided behind the lens 57, and the light emitted from the LED 58 passes through the lens 57 and reaches the tip of the first fiber 101 or the second fiber 102.

[0022] Another fiber 120 is inserted to the innermost part of the hole 70 (the innermost part in the X-axis direction). At the innermost part of the hole 70, the tip of the other fiber 120 faces the light receiving module 55, and the light emitted from the tip of the other fiber 120 reaches the light receiving module 55.

[0023] FIG. 8 is an enlarged cross-sectional view of the C1 part of FIG. 6 and the C2 part of FIG. 7. The LED 58 is mounted on the PCB substrate 31 and projects light to the first fiber 101 or the second fiber 102. Also, a monitor light receiving element 80 for monitoring the light emission amount of the LED 58 is mounted on the PCB substrate 31. The monitor light receiving element 80 monitors whether the LED 58 maintains an appropriate light emission amount by receiving the light projected by the LED 58 to the fiber. The monitor light receiving element 80 feeds back the light emission amount of the LED 58, that is, the emission luminance, to a predetermined control circuit such as an APC (Automatic Power Control) control circuit, and the control circuit controls the LED 58 so that the LED 58 maintains a constant light emission amount (constant luminance) based on the feedback signal. By such control, the fiber sensor 1 can transmit an appropriate signal. The APC control circuit is mounted on the PCB substrate 31, for example.

[0024] At least one of the LED 58, the monitor light receiving element 80, and the APC control circuit may be directly mounted on the PCB substrate 31, or may be mounted on the light projecting module 54 and then connected to the PCB substrate 31.

[0025] The LED 58 projects light, for example, from the surface (i.e., the top surface) on the hole 62 side of the fiber holding component 50. In this case, the LED 58 emits light, for example, with a light emission range spreading about 180 degrees from the top surface toward the negative side of the X-axis. Note that the light intensity is strong (i.e., the light quantity is large) in the direction along the X-axis (the top surface direction), and the light intensity becomes weak (i.e., the light quantity becomes small) as the direction deviates from the X-axis direction (the side surface direction). Thereby, the fiber sensor 1 can perform stable sensing while maintaining high coupling of light to the fiber.

[0026] The fiber holding component 50 includes the hole 62 into which the fiber is inserted as described above. The fiber holding component 50 further includes an opening 63 located between the LED 58 and the hole 62, and a light shielding wall 64 located on the outer side in the radial direction of the opening 63 and between the monitor light receiving element 80 and the hole 62. In the present embodiment, the fiber holding component 50 has a light shielding portion having a light shielding function between the monitor light receiving element 80 and the hole 62, and the light shielding wall 64 is exemplified as an example of the light shielding portion.

[0027] The opening 63 is a space portion continuously formed from the innermost part of the hole 62, and the light shielding wall 64 is formed in an annular shape so as to surround the opening 63 on the outer side in the radial direction. In the present embodiment, the light shielding wall 64 is integrally formed with the main block of the fiber holding component 50, and no additional component for the light shielding wall 64 is used.

[0028] Further, the light-shielding wall 64 has a first contact portion 62a facing the innermost part of the hole 62, against which the first fiber end face of the first fiber 101 among the fibers can abut. Also, the opening 63 is formed continuously with the hole 62 on the LED 58 side of the hole 62. The light-shielding wall 64 has a second contact portion 63a smaller in diameter than the first contact portion 62a, facing the opening 63. The second fiber end face of the second fiber 102 smaller in diameter than the first fiber 101 can abut against the second contact portion 63a. The first fiber 101 has, for example, a diameter of 2.2 mm (φ2.2). The second fiber 102 has, for example, a diameter of 1.0 mm (φ1.0) or 0.75 mm (φ0.75). The fiber sensor 1 can arrange fibers having respective diameters at desired positions without providing parts for special positioning because the fiber holding component 50 has the first contact portion 62a and the second contact portion 63a having diameters corresponding to their respective sizes. Note that the LED 58 of the light projection module 54 is to be arranged facing the first contact portion 62a and the second contact portion 63a.

[0029] Thereby, the fiber holding component 50 can hold fibers of various diameters, and the function of abutting the fiber to fix it at a fixed position can be realized, enabling stable sensing.

[0030] Note that, as an example, a stepped structure is formed by the first contact portion 62a on the front side and the second contact portion 63a on the back side (the side closer to the LED 58) when viewed from the fiber side, but the stepped structure may be constituted by three or more contact portions. For example, the fiber sensor 1 can hold fibers of various diameters by being configured such that the contact portions closer to the LED 58 have smaller diameters.

[0031] Next, the behavior of the light projected from the LED 58 will be described.

[0032] The light L1 projected directly upward from the LED 58 travels straight without being reflected by the fiber. Also, the light L2 that enters the end face of the fiber at a small incident angle mostly enters the fiber and a part of it is reflected as shown by the broken line. However, since the reflection angle is also small, the reflected light L2A as shown by the broken line does not reach the monitor light-receiving element 80.

[0033] On the other hand, the light L3 that enters the end face of the fiber at a large incident angle partly enters the fiber and a part of it is reflected as shown by the broken line. In this case, since the reflection angle is large, if there is no light-shielding wall 64, the reflected light L3A as shown by the broken line may reach the monitor light-receiving element 80. Since the reflected light L3A is not the light originally projected by the LED 58, if the reflected light L3A reaches the monitor light-receiving element 80, the monitor light-receiving element 80 may not be able to accurately monitor the emission amount of the LED 58, and there is a possibility that the control circuit may not be able to correctly control the emission amount of the LED 58.

[0034] In the present embodiment, the light-shielding wall 64 serves to shield the light that should not be projected onto the monitor light-receiving element 80 among the light projected from the LED 58, such as the reflected light L3A. Therefore, even if the fiber is brought closer to the LED 58, the reflected light L3A that is projected from the LED 58 and reflected by the end face of the fiber inserted into the hole 62 is shielded by the light-shielding wall 64, so that it can be suppressed from being received by the LED 58. Specifically, the reflected light L3A stops traveling at a predetermined position P of the opening 63 which is the inner surface of the light-shielding wall 64. Also, since the distance between the fiber and the LED 58 can be reduced, the light coupling force can be ensured and the fiber sensor 1 can be miniaturized.

[0035] Also, since the light-shielding wall 64 exists, it is not necessary to make the opening 63 smaller than necessary, and it is possible to suppress a decrease in the light coupling force from the LED 58 to the fiber. Also, in the embodiment, without particularly providing another member, such as a light guide member that guides light to the monitor light-receiving element 80, a part of the fiber holding component 50 necessary for holding the fiber serves as the light-shielding wall 64, so that the fiber sensor 1 can be miniaturized and the cost can be reduced.

[0036] Also, the fiber holding component 50 is composed of, for example, a member having an optically opaque color. The optically opaque color is a color that does not transmit light (has no light transmissivity), for example, black. Also, the LED 58 exists on the extension of the longitudinal direction of the hole 62. That is, the LED 58 and the fiber are arranged coaxially.

[0037] Thereby, since the fiber holding component 50 has an optically opaque color, it is possible to suppress light leaking from the LED 58 toward the monitor light receiving element 80 or light from the fiber leaking to the monitor light receiving element 80 through the fiber holding component 50. Also, since the LED 58 and the fiber are arranged coaxially, high coupling of light can be achieved.

[0038] Next, the light projecting module 54 will be described.

[0039] The light projecting module 54 includes a PCB substrate 31 (at least a part thereof), an LED 58, and a monitor light receiving element 80. Further, the light projecting module 54 is formed of a light projecting resin and has light transmissivity, and includes a molding part 56 that molds the PCB substrate 31, the LED 58, and the monitor light receiving element 80. And a part of the light projected from the LED 58 is introduced into the monitor light receiving element 80 by reflection on the inner surface of the molding part 56, for example, like the light L4.

[0040] Thereby, due to one or more internal reflections in the molding part 56 of the light projecting module 54, the light from the LED 58 reaches the monitor light receiving element 80, so that the monitor light receiving element 80 can receive light. Note that the light L4 is also reflected by the surface of the light shielding wall 64.

[0041] The surface of the PCB substrate 31 on which the LED 58 and the light receiving element 80 for monitoring are mounted has, for example, an optically opaque color. Thereby, the fiber sensor 1 can absorb a certain amount of light by the PCB substrate 31, and it is possible to suppress light from leaking out of the PCB substrate 31 to the outside of the PCB substrate 31 or being diffusely reflected within the light projecting module 54. The PCB substrate 31 having an optically opaque color can be realized, for example, by black painting or black resist painting.

[0042] Next, the positional relationship between the LED 58 and the light receiving element 80 for monitoring will be described.

[0043] As shown in FIG. 8, the distance along the radial direction between the LED 58 and the light receiving element 80 for monitoring is D, the distance from the LED 58 to the light shielding wall 64 along the axial direction (insertion direction) of the fiber is d, the incident angle θ of the light projected from the LED 58 to the light shielding wall 64 is the critical angle θc, the refractive index of the mold portion 56 is n1, and the refractive index of the light shielding wall 64 is n2 (n1>n2). Under this condition, the distance D along the radial direction between the LED 58 and the light receiving element 80 for monitoring is preferably set to be longer than the shortest distance Dmin represented by the following (Equation 3). The shortest distance Dmin is the shortest distance along the radial direction between the LED 58 and the light receiving element 80 for monitoring. The shortest distance Dmin is the shortest distance among the distances at which the light projected from the LED 58 is totally reflected once at the boundary between the mold portion 56 and the light shielding wall 64 and reaches the light receiving element 80 for monitoring.

[0044] Specifically, regarding the incidence of light from the mold portion 56 to the light shielding wall 64 (fiber holding component 50), when n1>n2 and the incident angle θ is larger than the critical angle θc, the light does not enter from the mold portion 56 to the light shielding wall 64 and is totally reflected at the boundary between the mold portion 56 and the light shielding wall 64. According to Snell's law, the following (Equation 1) holds. sinθc=n2 / n1···(Equation 1)

[0045] On the other hand, the relationship between the distance d from the LED 58 to the light shielding wall 64 in the axial direction of the fiber, the shortest distance Dmin between the LED 58 and the light receiving element 80 for monitoring, and the critical angle θc is represented by the following (Equation 2). Tanθc = (Dmin / 2) / d ···(Equation 2)

[0046] Therefore, when the incident angle θ is the critical angle θc, the shortest distance Dmin along the radial direction between the LED 58 and the light receiving element 80 for monitoring is expressed by the following (Equation 3). Note that "*" indicates the multiplication sign. Dmin = 2d * Tanθc ···(Equation 3)

[0047] Also, when the critical angle θc is expressed using the refractive index n1 and the refractive index n2, it is expressed by the following (Equation 4).

[0048] [Number]

[0049] Thus, the shortest distance Dmin can be defined using the critical angle θc (sinθc = n2 / n1) for total reflection of the light projected from the LED 58. The distance D is a distance longer than the shortest distance Dmin. Therefore, the following (Equation 5) is satisfied. D > 2d * Tanθc ···(Equation 5) That is, the light receiving element 80 for monitoring is arranged at a position farther than the position on the PCB substrate 31 where the light projected from the LED 58 reaches when the light is reflected once on the surface of the light shielding wall 64 (the inner surface of the mold portion 56) at the critical angle θc.

[0050] Due to such an arrangement relationship between the LED 58 and the light receiving element 80 for monitoring, the fiber optic sensor 1 can be configured such that none of the light reflected by the fiber end face passing through the opening 63 reaches the light receiving element 80 for monitoring, and the light reflected by the mold portion 56 or the light shielding wall 64 of the light projecting module 54 can enter the light receiving element 80 for monitoring.

[0051] As a result, the fiber sensor 1 can prevent the reflected light from the fiber end face from reaching the light receiving element 80 for monitoring. Therefore, the fiber sensor 1 can accurately measure the light amount of only the light reflected by the light shielding wall 64 from the light projected from the LED 58, can accurately control the LED 58, and can perform stable sensing.

[0052] Next, the electrical connection of each member in the fiber sensor 1 will be described.

[0053] FIG. 9 is an enlarged cross-sectional view of the fiber sensor 1 in FIG. 1 taken along the XZ plane. In FIG. 9, a part on the negative X-axis side of the fiber sensor 1 is shown.

[0054] The fiber holding component 50 is made of, for example, a conductive resin and has conductivity. Also, the PCB substrate 31 and the screw 90 also have conductivity. The screw 90 is, for example, a tapping screw. The screw 90 passes through the through hole of the PCB substrate 31. As shown in FIG. 9, the screw 90 is fastened to the housing of the fiber sensor 1 with the ground electrode pad (not shown) of the PCB substrate 31 and the fiber holding component 50 interposed therebetween. Therefore, the fiber holding component 50 can be electrically connected to the ground of the PCB substrate 31 and can be stably electrically connected to the components (such as the LED 58 and the light receiving element 80 for monitoring) on the PCB substrate 31. Therefore, by electrically connecting the fiber holding component 50 and the ground of the PCB substrate 31 via the screw 90, the fiber sensor 1 can reduce electrical noise due to the shielding effect.

[0055] As described above, in the fiber sensor 1 of the present embodiment, since the light shielding wall 64 shields the reflected light reflected by the end face of the fiber inserted into the hole 62, it is possible to suppress the light other than the light from the LED 58 from being received by the light receiving element 80 for monitoring. Also, the end face of the fiber may not be a desired flat surface. For example, when it is cut by a free cut, it may have irregularities or may be inclined with respect to the extending direction of the fiber. Even in such a case, the fiber sensor 1 can suppress the extra light from being received by the light receiving element 80 for monitoring by the light shielding wall 64.

[0056] In addition, due to the presence of the light-shielding wall 64, the fiber sensor 1 does not need to make the opening 63 smaller than necessary, and it is possible to suppress a decrease in the coupling force of light from the LED 58 to the fiber. Further, the object to be detected (work) is becoming smaller, and when detecting a small work, the signal-to-noise ratio tends to be small. However, since the fiber sensor 1 can suppress a decrease in the light coupling force, the work can be detected stably.

[0057] In addition, since the fiber holding component 50 has a light-shielding function due to the light-shielding wall 64, for example, it is not necessary to provide a dedicated component for light shielding on the surface of the light-receiving element 80 for monitoring, the degree of freedom in design can be improved, and it can also contribute to the miniaturization of the fiber sensor 1. Further, since the fiber holding component 50 also has conductivity, it is not necessary to provide a dedicated component for electromagnetic shielding, and the electrical characteristics can also be stabilized.

[0058] In addition, in the fiber sensor 1, the light-shielding wall 64 facing the innermost part of the hole 62 and the opening 63 also serves as a stopper. Thereby, the fiber sensor 1 can make the insertion amount of the fiber (for example, the first fiber 101 or the second fiber 102) into the hole 62 constant, can fix the fiber at a constant position, and can also stabilize the light coupling.

[0059] In addition, since the fiber holding component 50 has an optical opaque color and conductivity, by being electrically connected to the ground of the PCB board 31, the entire inside of the fiber sensor 1 can be electromagnetically shielded, and it is possible to suppress electrical noise from interfering with the light-receiving element 80 for monitoring.

[0060] By generating the fiber holding component 50 having such functions as an integral component, the fiber sensor 1 can improve the assemblability, reduce the number of parts, and achieve cost reduction.

[0061] Although the various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modifications or corrections within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Further, within the scope not departing from the gist of the invention, the components in the above embodiments may be arbitrarily combined.

[0062] <Summary of this embodiment> As described above, the present disclosure describes at least the following matters. In the parentheses, corresponding components and the like in the above-described embodiments are exemplified, but the present disclosure is not limited thereto.

[0063] (Item 1) A substrate (PCB substrate 31), A light-emitting element (LED 58) mounted on the substrate and emitting light to the fiber (first fiber 101, second fiber 102), A light-receiving element (monitor light-receiving element 80) mounted on the substrate and monitoring the light emission amount of the light-emitting element, A fiber holding component (fiber holding component 50) holding the fiber, Comprising, The fiber holding component, A hole (hole 62) into which the fiber is inserted, An opening (opening 63) located between the light-emitting element and the hole, A light-shielding portion (light-shielding wall 64) located outside the radius direction of the opening and located between the light-receiving element and the hole, A fiber sensor (fiber sensor 1) comprising.

[0064] Thus, even when the fiber is brought close to the light-emitting element, the reflected light that is projected from the light-emitting element and reflected by the end face of the fiber inserted into the hole is blocked by the light-blocking portion, so that it is possible to suppress the light from being received by the light-receiving element. Further, since the light-blocking portion exists, it is not necessary to make the opening smaller than necessary, and it is possible to suppress a decrease in the coupling force of the light from the light-emitting element to the fiber. Further, since a part of the fiber holding component necessary for holding the fiber serves as the light-blocking portion without particularly providing another member, the fiber sensor can be miniaturized.

[0065] (Item 2) Further comprising a light projection module, The light projection module is, Comprising the substrate, the light-emitting element, the light-receiving element, and a molding portion (molding portion 56) having translucency and molding the substrate, the light-emitting element, and the light-receiving element. Due to reflection on the inner surface of the molding portion, the light projected from the light-emitting element is introduced into the light-receiving element. The fiber sensor according to Item 1.

[0066] Thus, due to internal reflection in the molding portion of the light projection module, the light from the light-emitting element reaches the light-receiving element, so that the light-receiving element can receive light.

[0067] (Item 3) The surface of the substrate on which the light-emitting element and the light-receiving element are mounted has an optically opaque color. The fiber sensor according to Item 1 or 2.

[0068] Thus, it is possible to suppress light from leaking out of the substrate to the outside of the substrate.

[0069] (Item 4) The light-blocking portion is, A first contact portion (first contact portion 62a) capable of contacting the first fiber end face of the first fiber (first fiber 101) that is the fiber, facing the innermost part of the hole. Opposite to the opening, there is a second contact portion (second contact portion 63a) that is continuously formed with the first contact portion, has a smaller radius than the first contact portion, and the end face of the second fiber (second fiber 102) having a smaller radius than the first fiber is capable of contacting. The fiber sensor according to any one of Items 1 to 3.

[0070] Thereby, the fiber sensor can hold fibers of various diameters, the light-shielding portion can realize the function of holding the fiber in addition to the light-shielding function, and contact with the light-emitting element can be suppressed.

[0071] (Item 5) The fiber sensor further includes a lens (lens 57) disposed between the opening and the light-emitting element. The fiber sensor according to any one of Items 1 to 4.

[0072] Thereby, the fiber sensor does not allow the fiber to reach the lens on the back side of the opening when the fiber abuts by the first contact portion and the second contact portion. Therefore, the fiber sensor can prevent the fiber end face from contacting the lens, suppress damage to the lens and wire breakage of the light-emitting element, etc., and enable stable detection. In addition, the fiber sensor can collect the light projected from the light-emitting element by the lens to increase the light intensity and make the light enter the fiber.

[0073] (Item 6) The fiber holding component is composed of a member having an optically opaque color and conductivity, and the light-emitting element exists on the extension of the longitudinal direction of the hole. The fiber sensor according to any one of Items 1 to 5.

[0074] Thereby, since the fiber holding component has an optically opaque color, it is possible to suppress light leaking from the light-emitting element to the light-receiving element or light from the fiber leaking to the light-receiving element through the fiber holding component. In addition, since the fiber holding component has conductivity, it can be electrically connected to, for example, the ground of the substrate, and can be stably electrically connected to components on the substrate (such as the light-emitting element, the light-receiving element, etc.).

[0075] (Item 7) The light-emitting element and the light-receiving element are arranged on the same plane, The fiber optic sensor according to any one of Items 1 to 6.

[0076] As a result, the fiber optic sensor can efficiently arrange the light-emitting element and the light-receiving element, and it becomes easier for the light from the light-emitting element to enter the light-receiving element.

[0077] (Item 8) The distance D between the light-emitting element and the light-receiving element is When the distance along the longitudinal direction of the hole from the light-emitting element to the light-shielding portion is d, the angle when the incident angle of the light projected from the light-emitting element to the light-shielding portion is the critical angle is θc, and * is the multiplication sign, it is a distance longer than the distance (shortest distance Dmin) that satisfies 2d * Tanθc. The fiber optic sensor according to any one of Items 1 to 7.

[0078] As a result, it is possible to prevent the reflected light from the fiber end face from reaching the light-receiving element. Therefore, it is possible to accurately measure only the amount of light of the light projected from the light-emitting element and reflected by the light-shielding portion, accurately control the light-emitting element, and perform stable sensing.

[0079] (Item 9) The light-emitting element projects light only from the surface on the hole side of the fiber holding component. The fiber optic sensor according to any one of Items 1 to 8.

[0080] As a result, the fiber optic sensor can perform stable sensing while suppressing the cost while maintaining high coupling of light to the fiber.

Industrial Applicability

[0081] The present disclosure is useful for a fiber optic sensor or the like that can suppress the entry of disturbing light into a light-receiving element for monitoring the light emission amount of a light-emitting element and can achieve miniaturization and high coupling of light.

Explanation of Symbols

[0082] 1 Fiber Optic Sensor 10 Main Body 31 PCB Substrate (An Example of a Substrate) 50 Fiber Holding Component 51 Main Block 52 Clamping Member 53 Clamping Lever 54 Light Emitting Module 55 Light Receiving Module 56 Molded Part 57 Lens 58 LED (An Example of a Light Emitting Element) 62 Hole 62a First Contact Portion 63 Opening 63a Second Contact Portion 64 Light Shielding Wall 80 Light Receiving Element for Monitoring (An Example of a Light Receiving Element) 90 Screw 101 First Fiber (An Example of a Fiber) 102 Second Fiber (An Example of a Fiber) 120 Other Fiber L1, L2, L3 Light L3A Reflected Light

Claims

1. A substrate, a light-emitting element mounted on the substrate for projecting light onto an optical fiber, a light-receiving element mounted on the substrate for monitoring the amount of light emitted by the light-emitting element, and a fiber holding component for holding the optical fiber, wherein the fiber holding component includes a hole into which the optical fiber is inserted, an opening located between the light-emitting element and the hole, and a light-shielding portion located radially outside of the opening and between the light-receiving element and the hole, a fiber sensor.

2. further comprising a light projection module, wherein the light projection module includes the substrate, the light-emitting element, the light-receiving element, and a molding portion having translucency and molding the substrate, the light-emitting element, and the light-receiving element, and light projected from the light-emitting element is introduced into the light-receiving element by reflection on the inner surface of the molding portion, the fiber sensor according to Claim 1.

3. the surface of the substrate on which the light-emitting element and the light-receiving element are mounted has an optically opaque color, the fiber sensor according to Claim 1 or 2.

4. the light-shielding portion includes a first contact portion facing the innermost portion of the hole and capable of contacting a first end face of a first optical fiber which is the optical fiber, and a second contact portion facing the opening and continuously formed with the first contact portion, having a smaller radius than the first contact portion, and capable of contacting a second end face of a second optical fiber having a smaller radius than the first optical fiber, the fiber sensor according to Claim 1 or 2.

5. further comprising a lens disposed between the opening and the light-emitting element, the fiber sensor according to Claim 3.

6. the fiber holding component is composed of a member having an optically opaque color and conductivity, and the light-emitting element is present on an extension in the longitudinal direction of the hole, the fiber sensor according to Claim 1 or 2.

7. the light-emitting element and the light-receiving element are disposed on the same plane, the fiber sensor according to Claim 1 or 2.

8. the distance D between the light-emitting element and the light-receiving element is under the condition that the distance along the longitudinal direction of the hole from the light-emitting element to the light-shielding portion is d, the angle when the incident angle of the light projected from the light-emitting element to the light-shielding portion is the critical angle is θc, and * is the multiplication sign, D > 2d * Tanθc is satisfied, the fiber sensor according to Claim 7.

9. the light-emitting element projects light only from the surface of the fiber holding component on the hole side, the fiber sensor according to Claim 1 or 2.

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