JPH10133056A - Connection structure among optical element, light emitting element using the same optical element and optical fiber, connection structure between optical fiber and optical fiber, connection structure between light receiving element and optical fiber, optical fiber device, light emitting device, and light receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the efficiency of optical coupling between elements such as a light emitting element, an optical fiber, and a light receiving element, and optical components. SOLUTION: A light acquiring element 14 formed of a nearly transparent material and a light guide element 15 which has a larger refractive index than the light acquiring element 14 and is formed of a nearly transparent material in a nearly conic or truncated cone shape are provided, and optical components such as a projector 12 and an optical fiber 11 are connected to each other through an optical element 10 which is so constituted that the light projection surface 15a (base of conic body) of the light guide element 15 is exposed on the light acquiring element 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical element, a connection structure between a light emitting element and an optical fiber using the optical element, a connection structure between an optical fiber and an optical fiber, a connection structure between a light receiving element and an optical fiber, Optical fiber devices, light emitting devices,
The present invention relates to a light receiving device and a photoelectric sensor.

[0002]

2. Description of the Related Art A conventional optical fiber type photoelectric switch has a light emitting device and a light receiving device. A light emitting optical fiber has a base surface facing a front surface of the light emitting device. And the distal end face of the light emitting optical fiber and the distal end face of the light receiving optical fiber are opposed to each other. Thus, the light emitted from the light emitter passes through the light emitting optical fiber and is emitted from the tip of the light emitting optical fiber,
Light emitted from the light emitting optical fiber enters the light receiving optical fiber, propagates through the light receiving optical fiber, and enters the light receiver.
Also, if an object enters the space between the distal end face of the light emitting optical fiber and the distal end face of the light receiving optical fiber, the light emitted from the light emitting optical fiber is blocked by the object, and the light is received by the light receiver. Since the light does not enter, the object is detected.

[0003]

However, the conventional photoelectric switch has the following problems. First, FIG. 1 shows a structure of a coupling portion between a light projector 1 and a core 2a of a light emitting optical fiber. The light projecting optical fiber has a structure in which the core 2a is merely butted against the light emitting surface 4 of the light projecting device 1 fixed to a housing (not shown). However, as shown in FIG.
A light emitting element 7 such as an LED chip is mounted on one lead 6, and the light emitting surface 4 and the light emitting element 7 are separated from each other. From the light emitting element 7, light r
Is emitted, but only a small amount of the light r (the shaded area in FIG. 2) is incident on the core 2a of the light projecting optical fiber. Therefore, the optical coupling efficiency between the light projector 1 and the core 2a is very low, for example, 1 mm in diameter.
The plastic fiber (core diameter) has a low value of about 7%. Therefore, the detectable distance is much shorter than that of a general non-optical fiber type photoelectric switch.

[0004] Optical fibers lack flexibility and have a large minimum bending radius. Therefore, if it is difficult to handle at the facility,
A relatively flexible optical fiber with a small core diameter may be used. In this case, since the amount of light incident on the optical fiber is proportional to the area of the end face of the core, the optical coupling efficiency is further lower than that of a normal optical fiber.
The optical coupling efficiency of a 2 mm plastic fiber is about 2%. For this reason, the detection distance is further reduced, and the use is limited.

In order to improve the optical coupling efficiency between the projector 1 and the optical fiber for projection, the end face of the optical fiber for projection is processed into a spherical shape, or the light exit surface 4 of the projector 1 is formed into a lens shape. However, there are problems such as the necessity of high-precision optical axis positioning, so that the structure is complicated and the connection work is difficult, the reliability in measurement is reduced, and the cost is increased.

In order to improve the detection distance of the optical fiber type photoelectric switch, it is sufficient to increase the light emission current supplied to the light emitter 1, but the heat generation of the circuit is increased.
There is a limit in increasing the light emission current, and the power consumption also increases.

Further, in order to increase the level of a light-receiving signal taken out of the light-receiving device, it is necessary to increase the amplification factor of the amplifier circuit. Therefore, even internal noise and external noise of the circuit are amplified, which causes a malfunction. Had become.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and has as its object to provide a light emitting device,
An object of the present invention is to increase the efficiency of optical coupling between elements such as optical fibers and light receiving elements or optical components.

[0009]

An optical element according to the first aspect of the present invention has a light trapping region formed of a substantially transparent material, a substantially conical body or a substantially cone shape having a refractive index larger than that of the light trapping region. A light guiding region formed in the shape of a pedestal, an outer peripheral surface of the light guiding region is wrapped in the light capturing region, and an end surface on a large side of the area of the light guiding region is exposed from the light capturing region. It is characterized by doing. Here, being substantially formed in a cone or a truncated pyramid typically means a cone, a truncated cone, a pyramid, a truncated pyramid, and the like, and includes a considerably deformed shape thereof. . The term “substantially transparent” also includes a case where it is transparent.

The light incident on the light capturing area from the end face opposite to the end face on which the area of the light guiding area having the larger area is located is totally reflected by the outer peripheral surface of the light capturing area, so that the light capturing area is formed. Trapped in Light that has entered the light guiding region from the light capturing region is totally reflected at the outer peripheral surface of the light guiding region, and is emitted from the end surface of the light guiding region at a small emission angle.

Therefore, it is possible to convert the outgoing angle of the light incident on the optical element into a small angle and emit the light from the optical element. Further, when two optical components are connected via an optical element, the optical coupling efficiency can be increased.

According to a second aspect of the present invention, in the optical element of the first aspect, a projection is provided on an outer peripheral surface of the light capturing area.

Thus, even when the optical element is inserted into the hole for holding the optical element, an air layer is secured between the inner wall surface of the hole and the light capturing area by the projection. The reason for securing the air layer is that if the outer peripheral surface of the light capturing area is in close contact with another member, light in the light capturing area may be absorbed or transmitted.

Therefore, in the case where the optical element is inserted into the hole, the outer peripheral surface of the light capturing region (the interface between the light capturing region and the air layer).
Since the light can be totally reflected by the optical element, the function of the optical element is not impaired, and the use of the optical element is expanded.

According to a third aspect of the present invention, there is provided a connection structure between a light emitting element and an optical fiber, wherein the optical element according to the first aspect is configured such that an end face of the light guiding region having a large area faces the end face of the optical fiber. The light emitting element and the end face of the optical fiber.

Thus, light emitted from the light emitting element can be made to enter the optical fiber at a small emission angle, and the optical coupling efficiency between the light emitting element and the optical fiber can be increased. Further, since it is not necessary to increase the light projection current, power consumption can be reduced.

According to a fourth aspect of the present invention, there is provided a connection structure between an optical fiber and an optical fiber, wherein the end face of the optical element having a large light guiding region has an end face facing the end face of the optical fiber on the light receiving side. Thus, the optical fiber is disposed between the end face of the optical fiber on the light emitting side and the end face of the optical fiber on the light receiving side.

Thus, light emitted from one end face of the optical fiber can be made incident on the other end face of the optical fiber at a small outgoing angle, and the optical coupling efficiency between the optical fibers can be increased. Further, a thick optical fiber can be converted into a thin optical fiber without lowering the light transmission efficiency.

According to a fifth aspect of the present invention, there is provided a connection structure between a light receiving element and an optical fiber, wherein the optical element according to the first aspect is configured such that an end surface of the light guiding region having a large area faces the light receiving element. , And between the optical fiber end face and the light receiving element.

Therefore, light emitted from the optical fiber can be made to enter the light receiving element at a small emission angle, and the optical coupling efficiency between the optical fiber and the light receiving element can be increased. In addition, since it is not necessary to increase the amplification factor of the light receiving circuit, malfunction due to various noises can be prevented.

An optical fiber device according to a sixth aspect is characterized in that the optical element according to the first aspect is provided on an end face of the optical fiber. Here, the optical fiber may be a light receiving side optical fiber or a light projecting side optical fiber, and the end face of the optical fiber may be a light receiving end or a light emitting end.

Thus, when the optical fiber is coupled to an optical component such as a light emitting element, a light receiving element, or another optical fiber, the optical coupling efficiency between the optical fiber and the optical component can be increased. Further, since it is not necessary to subject the end face of the optical fiber to lens processing, new investment can be reduced.

According to a seventh aspect of the present invention, in the light emitting device, the optical element according to the first aspect is configured such that an end face of the light guide region opposite to the end face having a larger area faces the light emitting element.
It is characterized by having.

However, when the light emitting device is coupled to an optical component such as an optical fiber, the light emitting device can be coupled with a small emission angle, and the optical coupling efficiency between the light emitting device and the optical component such as an optical fiber can be increased. it can. Furthermore, since it is not necessary to increase the light projection current, power consumption can be reduced.

An eighth aspect of the present invention provides the light receiving device, wherein the optical element according to the first aspect is provided such that an end face of the light guide region on a side having a large area faces the light receiving element. I have.

However, when the light receiving device is coupled to an optical component such as an optical fiber, the light receiving device can be coupled with a small emission angle, and the optical coupling efficiency between the light receiving device and the optical component such as an optical fiber can be increased. it can. Further, since it is not necessary to increase the amplification factor of the light receiving circuit, malfunction due to various noises can be prevented.

According to a ninth aspect of the present invention, there is provided a photoelectric sensor including a sensor body having a light projecting element, a light receiving element, and a signal processing circuit, and optical fibers for projecting and receiving light. The optical element described in 1 is arranged between at least one of between the light emitting element and the end face of the light emitting optical fiber, or between the end face of the light receiving optical fiber and the light receiving element.

As in the photoelectric sensor according to the ninth aspect, the optical element of the present invention can be widely used for improving the optical coupling efficiency in a connection structure between optical components in an optical device.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 3 is a diagram showing a state in which a light projector 12 and a light emitting optical fiber 11 are coupled by an optical element 10 in a connection structure between a light projector and an optical fiber according to an embodiment of the present invention. It is. The connection structure between the light projector and the optical fiber is provided, for example, in an optical fiber type photoelectric switch.

As shown in the sectional view of FIG. 4, the optical element 10 has a columnar light trapping element 14 for confining the light r entering from the incident surface 14a, and has a higher refractive index than the light trapping element 14. The light guiding element 15 has a pyramidal or frustum-shaped light guiding element 15 for guiding the light r confined in the capturing element 14 to the outside, and the light guiding element 15 is such that its light exit surface 15a is exposed to the outside. It is embedded in the light capturing element 14.

The light capturing element 14 is formed of a transparent optical plastic, the diameter of the light incident surface 14 a is smaller than the outer diameter of the light emitting surface 12 a of the light projector 12, and the core diameter of the light projecting optical fiber 11. The light emitting surface 12a is arranged so as to be close to or close to the light emitting surface 12a. The incident surface 14a has a uniform refractive index.

The light receiving side end face 11a of the light projecting optical fiber 11 is disposed on the light emitting surface 14b side of the light capturing element 14 so as to be close to or close to the light emitting side.
The diameter of 4b is larger than the cross-sectional area of the core of the light projecting optical fiber 11 like the incident surface 14a. In the center of the exit surface 14b, the column and the central axis are the same,
A conical light guiding element 15 formed of transparent plastic having a higher refractive index than the light capturing element 14 is embedded. Note that the refractive index of the optical element 10 is uniform in each region. The shape of the light capturing element 14 is not limited to a cylindrical shape, and the ridge of the outer peripheral surface 14c may have a slope or a curve, or may be a polygonal pillar.

The light guiding element 15 has a cone apex buried deepest in the light trapping element 14, and a light exit surface 15 a is formed flush with the exit surface 14 b of the light trapping element 14 and is flat. The light emitting surface 15a faces the light receiving side end surface 11a of the light projecting optical fiber 11 in close proximity or close contact, and the diameter d of the light emitting surface 15a is smaller than or substantially equal to the core diameter of the light projecting optical fiber 11. They are the same size. Note that the refractive index of the light guiding element 15 is uniform.

Further, the shape of the light guiding element 15 may be substantially a cone-like shape. For example, as shown in FIG. 5B, it may be a truncated cone, or as shown in FIG. As shown,
The shape may be a polygonal pyramid. Further, as shown in FIG. 5C, the ridge line of the outer peripheral surface 15b may be curved.

As shown in FIG. 6, the light projector 12 has a light emitting element 18 such as a light emitting diode (LED) or a semiconductor laser element (LD) mounted on a concave die pad 16 of a lead 17. The other lead 20 is bonded by a wire and sealed in a light-transmitting sealing body 19, and the light emitting element 18 is connected to the light emitting surface 12 a of the sealing body 19. The light r emitted from is transmitted.

The NA of the light projecting optical fiber 11 is
As shown in FIG. 3, the light r from the light projector 12 including the light beam emitted at an emission angle larger than (numerical aperture) is trapped in an area larger than the cross-sectional area of the core of the optical fiber 11 for light emission. The light is efficiently received by the incident surface 14a of the element 14. At this time, the light r emitted from the light emitting element 18 is a transparent resin (epoxy resin or the like) or glass sealing body 1 covering the light emitting element 18.
9, the outgoing angle is limited by its refractive index.

As shown in FIG. 3, the light r incident from the incident surface 14a of the light trapping element 14 is totally reflected by the outer peripheral surface 14c due to the difference in the refractive index between the light trapping element 14 and the air covering the outer periphery. It is trapped inside the capture element 14.

Further, most of the light r confined in the light trapping element 14 includes light rays incident at an angle larger than the NA of the light projecting optical fiber 11 (30 degrees or more in air). 15 inside.

The light r that has entered the light guiding element 15 has a lower refractive index in the light capturing element 14 that covers the periphery of the light guiding element 15 and thus has an outer peripheral surface 15b of the light guiding element 15 (the light capturing element 1).
The light is guided to the light emitting surface 15 a side while being totally reflected by the light emitting surface 15 a of the light guiding element 15 while being totally reflected by the light guiding element 15. At this time, the light r emitted from the light emitting surface 15a of the light guiding element 15 is converted to an angle smaller than the NA of the light projecting optical fiber 11.

The light r emitted from the light emitting surface 15a of the light guiding element 15 is applied to the light receiving side end surface 11 of the light projecting optical fiber 11.
The light enters from a and is coupled to the light projecting optical fiber 11.

Therefore, the light r emitted from the light emitting element 18
Most of the light including the light emitted at an angle larger than the NA of the light projecting optical fiber 11 as well as the light emitted at an angle smaller than the NA of the light projecting optical fiber 11 is transmitted to the light projecting optical fiber 11. Join. Therefore, the optical coupling efficiency between the light emitting element 18 and the light projecting optical fiber 11 is improved as compared with the conventional example.

Further, the light r emitted from the light emitting element 18
Is efficiently condensed by the optical element 10, the light r incident on the light projecting optical fiber 11 increases, and the light coupling efficiency between the light emitting element 18 and the light projecting optical fiber 11 is improved. When the light receiving element is connected to the other end, the light receiving intensity at the light receiving element 18 increases, and the detectable distance can be improved.

Further, it is not necessary to process the end face of the light projecting optical fiber 11 with a lens in order to lengthen the detection distance.
The detection distance can be improved at low cost.

Further, the light projecting optical fiber 1 having a small core diameter is used.
Even when the optical fiber 1 is used, the same detection distance as that when a normal optical fiber is used can be obtained, so that it is flexible, easy to handle, and the application of the light emitting optical fiber 11 is expanded.

Alternatively, since the detection distance is improved, it is not necessary to increase the light projection current supplied to the light projector 12, so that the current consumption can be suppressed and the heat generation of the photoelectric switch can be reduced.

(Embodiment) In the optical element 10 of this embodiment, the light guiding element 15 is made of PC (polycarbonate) and the light capturing element 14 is made of PMMA (polymethyl methacrylate). Is set to about 0.1. Even if the refractive index difference is larger than this, the effect of the present invention hardly changes. In addition, as a result of simulating the case where the optical element 10 of the present invention is used between the conventional light emitting element 18 and the light projecting optical fiber 11, the diameter of the light trapping element 14 is changed to the diameter of the light exit surface 15a of the light guiding element 15. It is most effective that the diameter is about 1.5 times, the length is about 1.1 times, and the inclination angle of the outer peripheral surface 15b of the light guiding element 15 is about 6 °.

(Second Embodiment) The optical element 10 of the present embodiment differs from the optical element 10 of the first embodiment in that FIG.
(A) As shown in (b), the outer peripheral surface 1 of the light trapping element 14
An annular, point-like or linear projection 22 is provided on the 4c edge,
The projections 22 ensure an air layer between the housing and the optical element 10 so that the outer peripheral surface 14c of the optical element 10 does not adhere to the housing holding the optical element 10.

The light r that has entered the light trapping element 14 and has reached the outer peripheral surface 14c of the light trapping element 14 is totally reflected due to the difference in the refractive index from the air layer, so that the light trapping element 14 can be efficiently produced. Trapped inside.

As described above, the light r incident on the light capturing element 14 from the light incident surface 14a is totally reflected by the difference in the refractive index on the outer peripheral surface 14c which is the boundary surface with the air layer 24, so that the light r is efficiently emitted. r can be captured, the light coupling efficiency of the light projecting optical fiber 11 is further improved, and the detection distance is further improved. Alternatively, when it is not necessary to extend the light projecting distance, it is possible to reduce the amount of power to the light emitting element 18 to reduce power consumption.

(Third Embodiment) In this embodiment, as shown in FIG. 8, a housing 2 for fixing the optical element 10 is used to secure an air layer outside the outer peripheral surface 14c of the light capturing element 14.
A plurality of ring-shaped, dot-shaped, and linear-shaped projections 24 are provided on the inner side of 3.

When the optical element 10 is press-fitted into the housing 23, the projection 24 is slightly collapsed so that the optical element 10
If the optical element 10 is firmly fixed to the housing 23, there is no concern that the optical element 10 is firmly fixed and shifts in position. Alternatively, the light trapping element 14 is formed by injection molding using a translucent resin, and the parting line is formed by the projection 24.
Alternatively, an air layer may be secured between the outer peripheral surface 14c of the light capturing element 14 and the housing 23.

(Fourth Embodiment) As shown in FIG. 9, a connection structure 25 between an optical fiber and an optical fiber according to the present embodiment includes a first optical fiber 26 having a large core diameter connected to a light projector. An optical fiber-to-optical fiber connection structure 25 for connecting a second optical fiber 27 having a small core diameter via the optical element 10, comprising the optical element 10 of the first embodiment, wherein the first optical fiber 26 One end surface 26a of the second optical fiber 27 is close to or close to the incident surface 14a of the light capturing element 14, and one end surface 27a of the second optical fiber 27 is close to or close to the light exit surface 15a of the light guide element 15. .

By the way, when installing an optical fiber type photoelectric switch, it may be difficult to lay the optical fiber because the optical fiber is easily broken and the allowable bending radius is large. For this reason, a small-diameter fiber having a small core diameter and a small allowable bending radius may be used. However, when the cross-sectional area of the core of the optical fiber is reduced, the optical coupling efficiency with the light emitting element is further reduced, and the diameter is 0.5 m.
m about 2% for plastic fiber.

Therefore, the first optical fiber 26 having a large diameter is coupled to the light projector 12, and the optical fiber is required to have flexibility because of difficulty in laying. When converted to the second optical fiber 27 having a diameter, the installation is facilitated while suppressing a decrease in optical coupling efficiency. Here, the diameter of the optical element 10 is the first optical fiber 2
6 and larger than the diameter of the second optical fiber 27, the diameter d of the light exit surface 15a of the light guiding element 15 is made substantially equal to the diameter of the second optical fiber 27.

As a result, most of the light r from the first optical fiber 26 is made incident on the light trapping element 14 and collected by the light guiding element 15 having a high refractive index. Almost all light is incident on the optical fiber 27.

As described above, since the optical fiber can be converted into a smaller diameter optical fiber depending on the facility location, the facility space can be reduced, and the condition of the facility location can be flexibly handled.

(Fifth Embodiment) In the present embodiment, the fourth
In the embodiment, the second optical fiber 27 and the optical element 1
As shown in FIG. 10, an adhesive 28 such as an ultraviolet curing (UV) type or an anaerobic adhesive, which is transparent and has a refractive index close to that of the second optical fiber 27 or the light guiding element 15, as shown in FIG. It is fixed at. The adhesive 28 serves as a refractive index matching agent and can reduce Fresnel loss. As shown in FIG. 6, the other optical coupling parts such as the boundary between the light projector 12 and the optical element 10 are also made of an ultraviolet curable or anaerobic adhesive 28 having a refractive index close to the refractive index of the optical coupling part. The same operation and effect can be expected if they are bonded together.

(Sixth Embodiment) FIG. 11 is a diagram showing a connection structure between a light receiver and an optical fiber according to the present embodiment.
In the connection structure between the light receiver and the optical fiber according to the present embodiment, the light receiver 30 and the light receiving optical fiber 35 are coupled by the optical element 10. The light emitting surface 15a of the optical element 10 is joined to the light receiving surface of the light receiver 30 by a transparent adhesive 28. Further, the incident surface 14a of the light capturing element 14 is configured to be close to or close to the base end surface (the core end surface on the light emitting side) of the light receiving optical fiber 35.

The light receiver 30 has a configuration in which a support 31 on which a light receiving element 32 is supported is sealed by a sealing body 33 made of a transparent resin.
A lead 34 for extracting a detection signal from the second 2 protrudes. The light from the light receiving optical fiber 35 is incident on the light receiving surface of the light receiving element 32.

The light capturing element 14 is arranged such that the light incident surface 14a faces the base end face of the light receiving optical fiber 35 in close proximity or close contact, and the light receiving element 3 is disposed on the light emitting surface 14b side.
The two light receiving surfaces are arranged so as to face each other.
The light-emitting surface 14b of the light capturing element 14 is
The area is smaller than or approximately equal to the area of the second light receiving surface.

The light guiding element 15 has a substantially columnar shape in which the diameter of the light emitting surface 15 a is smaller than or substantially equal to the core diameter of the light receiving optical fiber 35, and the conical apex is embedded deepest in the light capturing element 14. The light exit surface 15a is formed flush with the exit surface 14b of the light trapping element 14 and is flat. The light emitting surface 15a faces the light receiving surface of the light receiving element 32 via the adhesive layer 28, and its diameter d is smaller than the outer diameter of the light receiving surface. The other configuration of the optical element 10 is the same as that of the first embodiment.

First, the light r emitted from the base end face of the light receiving optical fiber 35 enters the light capturing element 14 from the incident face 14a. Then, the incident light r is totally reflected by the outer peripheral surface 14c due to a difference in refractive index between the light capturing element 14 and the air covering the outer circumference, and is confined inside the light capturing element 14.

Most of the confined light r enters the light guiding element 15 because the light guiding element 15 has a higher refractive index, and further, the light capturing element r on the outer peripheral surface 15 b of the light guiding element 15. The light is totally reflected by the difference in refractive index between the light guide element 14 and the light guiding element 15. Then, the light r exits the light exit surface 15a of the light guide element 15 at a small exit angle, and
2 is incident on the light receiving surface.

As described above, since the light r from the light receiving optical fiber 35 can be incident on the light receiving element 32 without waste, the light receiving element 32 and the light receiving optical fiber 35
And the efficiency of optical coupling with the substrate can be improved. That is,
The light r emitted from the base end surface of the light receiving optical fiber 35 is efficiently condensed by the optical element 10 and the light r incident on the light receiving surface of the light receiving element 32 increases. And the light receiving intensity is increased, and the detectable distance can be improved.

Further, it is not necessary to process the end face shape of the light receiving optical fiber 35 in order to lengthen the detection distance, and the detection distance can be improved at low cost.

Further, since the optical coupling efficiency is improved, even when an optical fiber having a small core diameter is used, a detection distance equivalent to that when a normal optical fiber is used can be obtained, so that it is flexible and easy to handle. Thus, the use of the optical fiber for transmitting and receiving light is expanded.

Further, since the detection distance is improved, the amplification factor of the light receiving circuit can be suppressed, and malfunction due to various noises can be prevented.

(Seventh Embodiment) The optical fiber device of the present embodiment has a light receiving fiber head 42 provided at the light receiving side end of an optical fiber 41 as shown in FIG. The optical element 10 similar to that of the first embodiment is provided in the light-receiving fiber head 42, and the light-emitting surface 15 a thereof is close to or in close contact with the light-receiving side end surface 41 a of the optical fiber 41.

The light receiving fiber head 42 has the optical element 10 housed in a cylindrical casing 43.
Is provided with a concave portion 44 for embedding the optical element 10 in the center of the end surface 43a on the light incident side, and the end surface 43a on the opposite side.
At the center of b, a concave portion 45 for inserting the light receiving side end of the optical fiber 41 is provided. Then, both recesses 44,
Numeral 45 communicates inside the casing 43, and light r having entered the optical element 10 is transmitted to the light receiving side end surface 41 a of the optical fiber 41 from this communication portion. In addition,
As in the first embodiment, the incident surface 14 of the light trapping element 14
“a” is larger than the core diameter of the light receiving optical fiber 41 so that the incident light r is efficiently received.

Thus, the light r is transmitted to the receiving fiber head 42.
When the light r enters the light trapping element 14 from the incident surface 14a of the optical element 10 inside, the light r is confined in the light trapping element 14 and further penetrates the light guiding element 15, and is similar to the first embodiment. Most of the light r including the light beam projected at an angle larger than the NA of the light receiving optical fiber 41 is coupled to the light receiving optical fiber 41.

As described above, the light receiving fiber head 42 having the optical element 10 at the light receiving side end of the light receiving optical fiber 41
Is provided, the light receiving area can be increased, so that the light receiving amount can be increased and the detection distance can be improved as compared with the related art. Further, by adopting such a configuration, it is easier to adjust the optical axis than when a spherical or aspherical lens is arranged, and there is no need for spherical processing.

(Eighth Embodiment) In the light emitting device of the present embodiment, as shown in FIG. 13, the optical element 10 of the first embodiment is integrated with a projector 55 having a light emitting element 18, and The light emitting surface of the light emitting element 18 is sealed in the light capturing element 14.

Some of the sealing bodies 19 of the light emitting elements 18 in the conventional light emitting device are of a shell type for condensing the light r.
It is preferable that the end face of the light emitting optical fiber 11 and the light emitting surface of the light emitting element 18 be in close contact with each other, so that the shell type is not suitable for connecting the light emitting optical fiber 11.

Therefore, in the light emitting device of the present embodiment, the sealing body 19 of the light emitting element 18 is a light trapping element 14 of a cylindrical shape, and a transparent conical high refractive index is provided in front of the light emitting element 18. The light guiding element 15 is embedded.

Therefore, when the light is directly connected to the light projector as in the prior art, the light r
Also, since the light is totally reflected by the outer peripheral surface 14c of the light capturing element 14 and guided to the light guiding element 15 and enters the light projecting optical fiber 11, a light emitting device with high light coupling efficiency of the light projecting optical fiber 11 is realized. it can.

(Ninth Embodiment) As shown in FIG. 14, a light emitting device according to this embodiment has a cylindrical light trapping element 14.
Is adhered to the light emitting surface of the light projector 12 molded by the sealing body 19 with a transparent adhesive 29 to form a single component. Therefore, the light emitting element 1 sealed in the light projector 12
8, no large thermal stress is applied, and the reliability is improved.

(Tenth Embodiment) As shown in FIG. 15, a light-receiving device in an optical fiber photoelectric sensor according to the present embodiment includes a light-receiving device 51 having a light-receiving element 50 and an optical element 10 according to the first embodiment. Are integrated, and the light receiving surface of the light receiving element 50 is close to or close to the light emitting surface 15a of the light guiding element 15.

The light receiving device comprises a light receiver 51 and an optical element 10. In the light receiver 51, the light receiving element 50 is fixed to the support body 52, and the light receiving surface of the light receiving element 50 and the light emitting surface 15a of the light guiding element 15 face each other closely or closely. On the other hand, the incident surface 14 a of the light capturing element 14 is exposed on the front surface of the light receiver 51.

The light receiving element 50 is provided on the bottom of the support 52.
A lead 34 for taking out a detection signal from is projected. The light incident on the light incident surface of the light receiver 51 is
The light is collected on the light receiving surface of the light receiving element 50 by the optical element 10, and the light receiving efficiency is improved.

(Eleventh Embodiment) FIG. 16 is a perspective view showing the appearance of an optical fiber type photoelectric sensor according to this embodiment.
The optical fiber type photoelectric sensor has a sleeve 61 shown in FIG.
Thereby, the light emitting side end of the light receiving optical fiber 35 is connected to the photoelectric sensor main body 60, and the light receiving side end of the light emitting optical fiber 11 is similarly connected to the photoelectric sensor main body 60 by the sleeve 61B. Has become.

By the way, if the optical coupling efficiency of the optical fiber can be improved without modifying the conventional optical fiber photoelectric sensor,
Development and capital investment can be reduced. Therefore, in the present embodiment, the conventional photoelectric sensor main body 60 is used as it is, and the light receiving optical fiber 35 and the light projecting optical fiber 11 are connected via the sleeves 61 and 61B.
Are connected to the optical fiber connection openings 60b, 60a. Accordingly, the light receiving optical fiber 35 and the light projecting optical fiber 11 and the light emitting element 1 in the photoelectric sensor main body 60 are disposed.
8 and the light coupling efficiency with the light receiving element 67 are increased, and the detection distance is improved.

The sleeve 61 is formed in a cylindrical shape, and an insertion port 61c for inserting the light receiving optical fiber 35 is pierced at one end thereof, and the optical element 10 is mounted on the photoelectric sensor main body side end face 61a on the opposite side. The insertion hole 61c and the concave portion are in contact with the sleeve 61.
It communicates internally. The emission surface 14b of the optical element 10 and the end surface 61a of the sleeve 61 on the photoelectric sensor side are also provided.
Means that the end surface of the sleeve 61 is substantially in the same plane or slightly outside. And the sleeve 61
Of the conventional optical fiber jacket (4 in FIG. 12).
1b).

The fixing of the optical element 10 to the sleeve 61
A concave portion provided on the photoelectric sensor side end surface 61a of the sleeve 61 is provided on the incident surface 14a side of the light trapping element 14 (the optical element 10).
This can be realized by press-fitting the optical element 10 from the (light incident surface). Further, when the light receiving optical fiber 35 is inserted into the sleeve 61, the end face thereof and the light incident surface of the optical element 10 (the incident surface 14 a of the light capturing element 14) are close to or in close contact with each other. , The light receiving surface of the light receiving element is arranged to be close to or close to the light emitting surface 15a of the light guiding element 15.

The optical element 10 and the light-receiving optical fiber 35 are joined by inserting the light-receiving optical fiber 35 into the insertion port 61 c of the sleeve 61 having a split pin structure.
2, the female screw 63a of the nut 62 is screwed to the male screw 63b of the sleeve 61 to be joined and fixed. At this time, since the outer diameter of the optical element 10 is smaller than the jacket diameter of the light receiving optical fiber 35, even if the jacket of the light receiving optical fiber 35 is peeled off and only the core wire is inserted into the insertion port 61 c of the sleeve 61. Since the light receiving optical fiber 35 does not come into contact with the end face 61b of the sleeve 61 and the light receiving optical fiber 35 is not inserted more deeply than necessary, the optical element 10 is pushed out of the light receiving optical fiber 35 and falls off. I will not do it. That is, it can be easily fixed in the same manner as the conventional optical fiber fixing method.

Although the detailed structure of the optical fiber 11 for light projection is not shown, the sleeve 61 is attached to its light receiving end.
A sleeve 61B having the same structure as that described above is connected. However, the optical element 10 in the concave portion of the sleeve 61B is placed in the opposite direction to the case for light reception.

The optical fiber type photoelectric sensor is the same as the conventional one, and an optical fiber connection opening 60a for connecting the light projecting optical fiber 11 to the light emitting element 18 therein is provided on the front surface of the rectangular photoelectric sensor main body 60. An optical fiber connection opening 60 for connecting the light receiving optical fiber 35 to the internal light receiving element 67.
b is opened, and a processing circuit for controlling measurement is provided in the photoelectric sensor main body 60. In the figure, 60c is
Lock release buttons for the sleeves 61 and 61B inserted into the optical fiber connection openings 60a and 60b,
Power cable.

As shown in FIG. 18, the processing circuit includes a light emitting circuit 66 for causing the light emitting element 18 to emit light in accordance with the oscillation timing of the oscillation circuit 65, an amplifying circuit 68 for amplifying the detection signal of the light receiving element 67, and an amplifying circuit. A comparison circuit 69 for comparing the measured signal with a set value (threshold value), an indicator lamp 70 for displaying a result of the comparison, an output circuit 71 for outputting a measurement result to an external device or the like, and a power supply to the main body 60. Power supply circuit 72
It is composed of

First, the light receiving optical fiber 35 is inserted from the other end of the sleeve 61 to which the optical element 10 is fixed at one end, and the light receiving optical fiber 35 and the optical element 10 are brought into close or close contact. Then, the nut 62 is tightened, and the light receiving optical fiber 35 is fixed to the sleeve 61. further,
The light projecting optical fiber 11 is similarly fixed to the sleeve 61B. Subsequently, the sleeves 61 and 61B to which the optical fibers are connected are connected to the optical fiber connection openings 60a and 60b of the photoelectric sensor main body 60.

When the measurement is started, the light emitting element 18 emits light in accordance with the oscillation timing of the oscillation circuit 65, and most of the light r enters the light trapping element 14 from the incident surface 14a of the optical element 10 built in the sleeve 61. Invading and light guiding element 1
5 to efficiently couple the light to the optical fiber 11 for light projection.

Further, the light passes through the light receiving optical fiber 35 and enters the incident surface 14 a
From the light trapping element 14, is guided by the light guiding element 15, and efficiently enters the light receiving surface of the light receiving element 67.

As described above, the optical fibers 11 and 35 for projecting and receiving light are connected to the optical fiber type photoelectric sensor main body 60 by the sleeves 61 and 61B in which the optical element 10 is mounted. Without modifying the photoelectric sensor, the light coupling efficiency of the light emitting and receiving optical fibers 11 and 35 can be increased, and the detection distance can be increased.

[0092]

According to the present invention, between the light emitting element and the light projecting optical fiber, the bottom surface of the light guiding area exposed at one end face of the optical element is substantially brought into contact with the light receiving side end face of the optical fiber to capture light. The light emitted from the light-emitting element is efficiently captured from the bottom surface of the light capturing area by making the bottom surface of the region substantially contact the light-emitting surface of the light-emitting element. The optical coupling efficiency between the optical element and the light projecting optical fiber is improved, the light receiving intensity at the light receiving element is increased, and the detectable distance can be improved as compared with the related art.

Further, even if the end face shape of the optical fiber is not processed, the optical coupling efficiency of the optical fiber is improved, the light receiving intensity at the light receiving element is increased, the detectable distance is improved as compared with the conventional one, and the detection can be performed at low cost. The distance can be improved.

Furthermore, even when an optical fiber having a small core diameter is used, the same detection distance as that obtained when an ordinary optical fiber is used can be obtained, so that the use of a flexible and easy-to-handle optical fiber for light emission and reception is expanded.

Further, since the detection distance is improved, the amplification factor of the light receiving circuit can be suppressed, and malfunction due to various noises can be prevented.

Alternatively, by connecting the light projecting element in the optical fiber type photoelectric sensor and the light projecting optical fiber or connecting the light receiving element and the light receiving optical fiber by the sleeve having the built-in optical element, the conventional optical sensor can be used. The detection distance can be increased without modifying the optical fiber photoelectric sensor, and new investment can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a coupling portion between a light projector and a light emitting optical fiber according to a conventional example.

FIG. 2 is a diagram illustrating a state in which a small amount of light emitted from a light emitting element at a large emission angle is incident on an optical fiber.

FIG. 3 is a diagram showing a state in which a light projector and a light emitting optical fiber are coupled by an optical element in a connection structure between a light projector and an optical fiber according to an embodiment of the present invention.

FIG. 4 is a sectional view showing an optical element.

5A is a cross-sectional view and a front view showing another example of the optical element, and FIGS. 5B and 5C are cross-sectional views showing still another example of the optical element.

FIG. 6 is a cross-sectional view showing a connection structure between a light projector and a light emitting optical fiber.

FIGS. 7A and 7B are a side view and a front view showing an optical element having a projection on an outer peripheral surface according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing still another embodiment of the present invention, in which a projection is provided on a housing to which an optical element is fixed.

FIG. 9 is a view showing still another embodiment of the present invention, in which a first optical fiber and a second optical fiber are connected by an optical element.

FIG. 10 is a view showing still another embodiment of the present invention, in which an optical element is fixed to an end face of an optical fiber by an adhesive.

FIG. 11 is a view showing still another embodiment of the present invention, in which an optical element is adhered to a light receiving surface of a light receiver.

FIG. 12 is a sectional view showing an optical fiber head according to still another embodiment of the present invention.

FIG. 13 is a cross-sectional view showing a light emitting device in which an optical element is integrated according to still another embodiment of the present invention.

FIG. 14 is a view showing a light emitting device according to still another embodiment of the present invention, in which an optical element is bonded to a light exit surface of a light projector.

FIG. 15 is a sectional view showing still another embodiment of the present invention, which is a light receiving device in which an optical element is integrated with a sealing body.

FIG. 16 is a perspective view showing an appearance of an optical fiber type photoelectric sensor according to still another embodiment of the present invention.

FIG. 17 is a partially broken side view showing a sleeve and a nut.

FIG. 18 is a block diagram showing a processing circuit of the photoelectric sensor of the above.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 optical element 11 light emitting optical fiber 12 light emitting element 14 light capturing element 15 light guiding element 22, 24 projection 30, 51 light receiving element 35 light receiving optical fiber 60 optical fiber photoelectric sensor 61, 61B sleeve

 ──────────────────────────────────────────────────続 き Continuing from the front page (54) [Title of the Invention] Optical element, connection structure between light emitting element and optical fiber using the optical element, connection structure between optical fiber and optical fiber, light receiving element and optical fiber Connection structure, optical fiber device, light emitting device, light receiving device, and photoelectric sensor

Claims (9)

[Claims] 1. A light trapping region formed of a substantially transparent material, and a light guide formed with a refractive index larger than that of the light trapping region and formed in a substantially cone or substantially truncated cone shape by the substantially transparent material. An outer peripheral surface of the light guiding area is wrapped in the light capturing area,
An optical element, wherein an end surface of the light guiding region on the side with a larger area is exposed from the light capturing region. 2. The optical element according to claim 1, wherein a projection is provided on an outer peripheral surface of the light capturing area. 3. The optical element according to claim 1, wherein the end surface on the side of the light guide region having a larger area faces the end surface of the optical fiber, and is arranged between the light emitting device and the end surface of the optical fiber. A connection structure between a light emitting element and an optical fiber. 4. The optical element according to claim 1, wherein the end surface of the light guide region having a larger area faces the end surface of the optical fiber on the light receiving side, and the end surface of the optical fiber on the light emitting side and the light receiving side. An optical fiber-to-optical fiber connection structure disposed between the optical fiber and an end face of the optical fiber. 5. The optical device according to claim 1, wherein the optical guide region is disposed between the end surface of the optical fiber and the light receiving element such that the end surface of the light guiding region on the side with the larger area faces the light receiving device. Connection structure between the light receiving element and the optical fiber. 6. An optical fiber device comprising the optical element according to claim 1 on an end face of the optical fiber. 7. A light emitting device, comprising: the optical element according to claim 1 such that an end face on a side opposite to a side having a large area of the light guide region faces the light emitting element. . 8. A light receiving device, comprising: the optical element according to claim 1 such that an end surface of the light guiding region on a side having a large area faces the light receiving element. 9. A sensor body having a light projecting element, a light receiving element, and a signal processing circuit, and a photoelectric sensor including light emitting and light receiving optical fibers, wherein the optical element according to claim 1 is: A photoelectric sensor disposed between at least one of a light emitting element and an end face of a light emitting optical fiber or between an end face of a light receiving optical fiber and a light receiving element.