JP2011150287A - Optical transmitting and receiving device using one pof, and optical transmitting and receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitting and receiving device, configured to facilitate positioning and to be inexpensively constituted by using a general-purpose or commercially available light-emitting element or light-receiving element, a general-purpose or commercially available reflective photosensor or the like; and to provide an optical transmitting and receiving system using the same. <P>SOLUTION: One end 8 of a POF 5 is made into an inclined end surface having an angle to a plane vertical to a central axis 9 of the POF, a light-emitting element 1 and a light-receiving element 3 are arranged near the inclined end surface, and a detection object 6 is arranged near the other end 13 of the POF. Light from the POF is incident on the POF through the inclined end surface thereof by use of a light condensing means 2, transmitted inside the POF, and outputted from the other end of the POF. At least part of the outgoing light is caused to enter the POF again from the other end thereof by the detection object set near the other end. The incident light from the detection object is transmitted inside the POF and outputted from the inclined end surface. The outgoing light is detected by the light-receiving element by use of a light condensing means 4, and a signal thereof is digitized and then subjected to digital signal processing including threshold processing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical transmission / reception apparatus and an optical transmission / reception system using a single plastic optical fiber (hereinafter abbreviated as POF), which are suitable for inexpensive detection objects and bidirectional communication apparatuses.

  Various sensors are used for detecting an object, and one of them is an optical fiber sensor that connects an object to be detected and a detection circuit or a light source with an optical fiber. This optical fiber sensor is classified into a transmission type that detects a change in the amount of light due to an object blocking light, and a reflection type that is detected by reflected light from the object. Use of optical fiber maintains the insulation between the light source and the light receiving part and the object to be detected, and has the advantage that the light source and light receiving part can be installed at any position, providing excellent water resistance and environmental resistance. Yes.

  As shown in FIG. 1 of JP-A-2002-71553, a conventional example of a reflection-type optical fiber sensor is provided with a light projecting optical fiber and a detection optical fiber separately, and one end of the light projecting optical fiber. An LED element as a light source is installed in the vicinity, and the other end is installed in the vicinity of the detection target. In addition, a light receiving element is installed near one end of the detection optical fiber, and the other end is installed in the vicinity of the detection target, and an optical fiber sensor is constituted by two optical fibers as a whole.

  When a reflection type optical sensor is constituted by such two optical fibers, two optical fibers are required, which is disadvantageous in terms of cost and space, and an optical fiber from a light projecting element / light receiving element to a detector. There is a drawback that the pair becomes thicker and the flexibility of this part becomes worse.

  As shown in FIG. 1 of Japanese Utility Model Laid-Open No. 02-90540, FIG. 1 of Japanese Patent Laid-Open No. 07-98384, and FIG. One end of the optical fiber is converted into a single optical fiber by an optical coupler, an optical isolator or the like. The other ends of the two optical fibers are installed in the vicinity of the light projecting element and the light receiving element, respectively, and the other end of the converted one fiber is installed in the vicinity of the detector. Although the flexibility of one optical fiber portion is maintained, the two optical fiber portions and the portions such as the optical coupler and the optical isolator are less costly than the aforementioned Japanese Patent Laid-Open No. 2002-71553 FIG. Further disadvantages are disadvantageous.

As shown in FIG. 7 of Japanese Patent Laid-Open No. 2004-45825, the conventional example of bidirectional communication using a single-core fiber is flat when the end face of a POF having a diameter of about 1 mm has a spherical end face. In the case of having a surface, a transmitting unit having a lens and a light emitting element and a receiving unit having a lens and a light receiving element are arranged in the vicinity of the end surface, and the receiving efficiency of the receiving unit in the two cases is compared. . In both cases, the receiving unit is arranged so that a part of the receiving unit exists on the central axis of the optical fiber, and the light from the transmitting unit traverses the central axis of the optical fiber and transmits to the central axis of the optical fiber. In order to improve the reception efficiency, the light is incident on the peripheral portion on the opposite side of the end face of the optical fiber on the side away from the optical fiber.
The embodiment of this known example uses a relatively thin POF having a diameter of about 1 mm, and requires high precision for setting the optical system of the transmitter, and the elements to be used are special and expensive. Have disadvantages.

  Other conventional examples of bidirectional communication using a single-core fiber are shown in FIG. 1 (a) and FIG. 10 in JP-A-2003-262765, in the vicinity of the end face of a POF having a diameter of about 1 mm. The configuration is such that the transmission light is incident on a narrow area in the peripheral portion of the enlarged POF with an enlarged diameter. In this example. In the vicinity of the end face, the diameter increases, and the end face shape has a special shape for avoiding circular end reflection, and there is a disadvantage that it is expensive.

Another conventional example of bidirectional communication using a single-core fiber is an end face of an optical fiber having a diameter of about 1 mm or less, as shown in FIGS. 1, 2 and 12 of Japanese Patent Laid-Open No. 11-308179. Is provided at an angle with respect to the center axis of the optical fiber, and light from the semiconductor laser is passed through this end face through a waveguide for transmitting light having a core portion and a clad portion installed in parallel to the center axis of the optical fiber. The core portion and the clad portion, which are incident on the peripheral portion of the optical fiber and have an end face densely arranged on the end face of the optical fiber and installed parallel to the central axis of the optical fiber, An example in which light is received by a photodiode via a received light waveguide is described. In this example, as shown in FIG. 2 and the like, the arrangement of the light emitting element and the light receiving element needs to be within the diameter of the optical fiber. In addition, there is a drawback that optical alignment requires accuracy and is expensive.
In this publication, as an advantage of forming the end face of the optical fiber with an inclination, only the point that the reflected light of the transmitted light at the inclined end face is not easily input to the reception light waveguide is described. However, in this publication, it is assumed that the distance between the outgoing side end face of the transmitting optical waveguide or the incoming side end face of the receiving optical waveguide and the inclined end face of the optical fiber is set to be close or short. The effect that the central axis of the outgoing light of the light propagated in this way is bent at the inclined end surface is not described.

JP 2002-71553 A Japanese Utility Model Publication No. 02-90540 JP 07-98384 A JP 2002-94107 A JP 2004-45825 A JP 2003-262765 A JP-A-11-308179

However, in Patent Document 1 to Patent Document 4, at least a part of the optical fiber is composed of two, which is not preferable in terms of cost and flexibility.
In Patent Document 5 to Patent Document 7, POF having a diameter of about 1 mm or less is used and single-core bidirectional communication is performed. However, accuracy is required for optical axis alignment, and a dedicated light emitting element or light receiving device is used. It is not preferable in terms of cost, for example, it is assumed that an element or an optical fiber is used.

  In view of the above problems, the object of the present invention is easy to align, and can use general-purpose or commercially available light-emitting elements, light-receiving elements or general-purpose or commercially available reflective photosensors, and can be configured at low cost. An optical transmitter / receiver and an optical transmitter / receiver system using the same are provided.

  The technical means for solving the above-described problem is that at least a part of one end of a single POF having a numerical aperture of 0.4 to 0.7 and a core portion having a diameter of 1.8 mm to 5 mm. , Composed of an oblique end surface having an angle δ (10 degrees to 40 degrees) from a plane perpendicular to the central axis of the POF, and a symmetrical plane [the angle formed by the outline in the length direction of the POF and the oblique end surface portion is the acute angle. A plane that is perpendicular to a perpendicular line extending from the apex portion (hereinafter abbreviated as the sharpest angle portion of the oblique end surface) to the central axis of the POF and includes the central axis of the POF. The same applies to the following], the optical axes of the light receiving element and the light receiving condensing means are arranged on the sharpest angle side of the oblique end surface, and the POF opening angle is opposite to the acute angle portion of the oblique end surface with respect to the symmetry plane. The optical axes of the light emitting element and the light collecting condensing means are arranged inside, and at least part of the light from the light emitting element is incident from the one end of the POF using the light emitting condensing means and is transmitted through the POF. The emitted light from the oblique end surface of the received light is collected using a light receiving condensing means and detected by a light receiving element, and the output is passed through an AD converter, and signal processing having threshold processing It is a technical feature of the optical transmission / reception apparatus to input to the apparatus and output from the signal processing apparatus after the signal processing.

If the angle formed by the center of the outgoing light emitted from the oblique end surface of the light transmitted through the POF with respect to the central axis in the longitudinal direction of the POF is γ (degrees) (see FIG. 1),
sin [(δ−γ) π / 180] = n · sin [δπ / 180] (1)
Where n = index of optical fiber core (eg POF = 1.49)
δ = An angle (degree) formed by the oblique end surface of the POF with respect to a plane perpendicular to the central axis of the POF
(Hereinafter referred to as “emitted light central axis equation”).
That is, the central axis of the light emitted from the oblique end surface of the POF has a property of bending toward the sharpest angle side of the oblique end surface with respect to the central axis of the POF.
The sign of the clockwise angle is indicated by plus, and the sign of the counterclockwise angle is indicated by minus (the same applies hereinafter).

  A preferred first additional technical means for solving the above-described problem is that the optical axis of the light receiving condensing means is set to plus or minus 10 of the central axis of the outgoing light from the oblique end face of the light transmitted through the POF. And the optical axis of the light condensing means of the light emitting element is set within the opening angle of the one end of the POF.

  A preferred second additional technical means for solving the above-mentioned problems is that the optical axis of the light-emission condensing means is set within ± 10 degrees of the normal direction of the oblique end surface of the POF or the oblique end surface method of the POF. It is to set to the optical axis side of the condensing means of a light receiving element with respect to a line direction.

  A preferred third additional technical means for solving the above-mentioned problem is a combination of a light-emitting element, a light-collecting condensing means, a light-receiving element, and a light-receiving condensing means, which is integrated with the POF. It is in the point installed near this one end including a slant end face.

  A preferred fourth additional technical means for solving the above-described problem is that a collimating lens is used as the light-emission condensing means so that the light emitted from the light converging means becomes parallel light or approximate light.

  A fifth preferred additional technical means for solving the above-mentioned problem is to appropriately measure the output amount from the light receiving element in a state where there is no object to be detected or in a state where no communication signal exists, and the signal processing device measures them. The amount is stored, and the detection threshold of the output amount of the light receiving element is determined by reflecting the stored amount.

  A sixth preferred additional technical means for solving the above-mentioned problem is to appropriately measure the output amount from the light receiving element in both the presence / absence of the detected object and the presence / absence of the communication signal, and measure them in the signal processing device. The amount is stored, and the detection threshold value and the calibration value of the output amount of the light receiving element are determined based on the stored amount.

  A seventh preferred additional technical means for solving the above-mentioned problem is that a part of one end of the POF is a first oblique end surface having an angle of not less than 10 degrees and not more than 40 degrees from a plane perpendicular to the central axis of the POF. A symmetric plane that is perpendicular to the perpendicular from the sharpest portion of the outline of the POF parallel to the central axis of the POF and the first oblique end surface to the central axis of the POF and includes the central axis of the POF On the other hand, the optical axis of the light receiving element and the light collecting condensing means is arranged on the side of the sharpest angle portion, and the optical axis of the light emitting element and the light collecting condensing means is arranged on the side opposite to the sharpest angle portion. A second oblique end surface or an end surface perpendicular to the central axis of the POF having an angle opposite to the first oblique end surface with respect to a plane perpendicular to the central axis of the POF is formed on the other part of the one end. A second oblique end surface or an end surface perpendicular to the central axis of the POF and the first oblique end surface; A light shield is installed near the field, and at least part of light from the light emitting element is incident on the POF via the second oblique end face or the end face perpendicular to the central axis of the POF. The optical axis of the light means and the optical axes of the light emitting element and the light collecting condensing means are respectively located on opposite sides with respect to the symmetry plane and the light shielding body.

  A preferred eighth additional technical means for solving the above-mentioned problem is that a portion optically connected to a POF having a core diameter of 1.5 mm or less is provided in the POF via the POF diameter conversion section. There are points to include.

By using a large-diameter POF with a core portion having a diameter of 1.8 mm or more and 5 mm or less, high accuracy is not required for axial alignment or the like. Further, by making the end face of the POF a bevel end face, the central axis of the light emitted from the POF is bent in the direction of the sharpest apex of the bevel end face as shown in the equation (1). By installing the light receiving element and the optical axis of the light receiving condensing means on the region side including the sharpest angle portion, efficient light reception is possible. In addition, the optical axis of the light emitting element and the light collecting condensing means can be installed on the opposite side of the light receiving element with respect to the plane of symmetry, and a POF having a large opening angle of 0.4 to 0.6 is used as the POF opening angle. As a result, an optical transmission / reception apparatus can be obtained in which the light reflected from the oblique end surface of the light from the light emitting element is not easily incident on the light receiving condensing means and the light from the light emitting element is efficiently incident on the POF. There are advantages to being
However, since it is difficult to completely prevent unnecessary light including light reflected from the oblique end face of the light emitting element and diffused light from entering the light receiving element, the present invention detects the light receiving element. After the signal is converted into a digital signal by an AD converter, signal processing for removing an unnecessary signal portion is performed by a signal processing device. The AD conversion and the signal processing unit can be handled by a general-purpose one-chip microcomputer that can be obtained for several tens of yen to several hundreds of yen, so that there is no particular problem in terms of cost.

  In addition, the present invention solves the above problems as compared with a conventional method in which an optical fiber for a light emitting element and an optical fiber for a light receiving element are used and coupled to one optical fiber using an optical coupler. By means of technical means, a light emitting element, a light receiving element and these light condensing means may be arranged near one end of one flexible POF, so that it is much smaller, cheaper and more flexible than the conventional method. There is an advantage that an optical transmission / reception system capable of detecting an object to be detected at the other end of the POF can be obtained. Needless to say, the POF portion possesses insulating properties, dustproof properties, waterproof properties, and the like.

  The optical axis of the light collecting condensing means is set within plus or minus 10 degrees of the central axis (Equation (1)) of the emitted light transmitted through the POF, and the optical axis of the light collecting condensing means is According to a preferred first additional technical means for solving the above-mentioned problem, which is installed in a range satisfying the transmission condition in the POF, the amount of light with respect to the outgoing light from the oblique end surface of the light transmitted through the POF Since the optical axis of the condensing means of the light receiving element is installed near the central axis of the emitted light having a large size, there is an advantage that an optical transmission / reception apparatus in which the amount of received light increases can be obtained.

  The above-mentioned problem is that the optical axis of the light collecting condensing means is set within plus or minus 10 degrees in the normal direction of the oblique end surface of the POF or on the optical axis side of the light receiving condensing means with respect to the normal direction of the end face of the POF. According to the second preferred additional technical means for solving the above problem, the light directly reflected by the POF end face from the light emitting element is reflected as it is by the substantially same optical path (within plus or minus 10 degrees). However, it is reflected at an angle away from the light receiving element. Therefore, there is an advantage that an optical transmission / reception apparatus that makes it easy to prevent the light directly reflected by the oblique end surface of the POF from entering the light receiving condensing means can be obtained.

A light emitting element, a light collecting condensing means, a light receiving element, and a light receiving condensing means are integrally connected to each other in the vicinity of the one end of the POF. According to the additional technical means, if the optical axes and positions of the light-emitting element, the light-collecting light-collecting means, the light-receiving element, and the light-receiving light-collecting means are coupled together in a preferable state in advance, It is not necessary to adjust the optical axis and position of the light collecting means, light receiving element, and light receiving light collecting means individually, and it is only necessary to match the optical axis and position of this integrated unit with POF, so it is inexpensive and has high performance. There is an advantage that becomes possible.
Furthermore, if an appropriate angle between the optical axis of the light-collecting condensing means and the optical axis of the light-receiving condensing means is selected, a commercially available integrated reflective photosensor can be used to By installing it near the one end of the POF, there is an advantage that an optical transmission / reception apparatus and optical transmission / reception system capable of detecting an object to be detected and single-core bidirectional communication can be obtained in a compact, easy and inexpensive manner.

  According to a fourth preferred additional technical means for solving the above-mentioned problem, a collimating lens in which the light emitted from the condensing means becomes parallel light or light similar thereto is used as the light condensing means. Therefore, the amount of light incident on the POF can be increased and the amount of light emitted from the other end of the POF can be increased. When detecting an object to be detected near the other end of the POF, the amount of light incident again from the other end of the POF can be increased. As a result, the amount of light emitted from the oblique end surface of the POF is also increased. The signal-to-noise ratio of the optical signal detected by the light receiving element can be greatly improved, and the presence / absence of an object to be detected can be reliably detected, or the optical signal can be reliably transferred in single-core bidirectional communication. There is an advantage that an optical transmission / reception apparatus and an optical transmission / reception system that can be obtained are obtained.

Measure the output amount from the light receiving element when there is no detected object or no communication signal, store the measured amount in the signal processing device, and reflect the stored amount to output the light receiving element. According to a fifth preferred additional technical means for solving the above-mentioned problem for determining the detection threshold value, there is an unnecessary light amount that cannot be ignored, and the value gradually changes over time. In addition, there is an advantage that an optical transmission / reception apparatus and an optical transmission / reception system capable of reliably detecting the presence / absence of an object to be detected and performing reliable transmission / reception of optical signals in bidirectional communication can be obtained.

  Measure the output amount from the light receiving element in both the presence / absence of the detected object and the presence / absence of the communication signal, and store the measured amount in the signal processing device. Further, according to a sixth additional technical means for determining the output threshold value and the calibration value of the light receiving element, which is preferable for solving the above-mentioned problem, the magnitude of the reflected light from the object to be processed Therefore, there is an advantage that an optical transmission / reception apparatus and an optical transmission / reception system can be obtained.

  A part of one end of the POF is constituted by a first oblique end surface having an angle of 10 degrees or more and 40 degrees or less from a plane perpendicular to the central axis of the POF, and an outline of the POF parallel to the central axis of the POF A light receiving element and a light collecting condensing means on the side of the acute angle portion with respect to a symmetrical plane perpendicular to a perpendicular line from the sharpest angle portion to the first oblique end surface to the central axis of the POF and including the central axis of the POF The light axis of the light emitting element and the light collecting condensing means are arranged on the opposite side of the sharpest angle portion, and the other portion of the one end of the POF is in a plane perpendicular to the central axis of the POF. And an end surface perpendicular to the central axis of the second oblique end surface or POF having an angle opposite to the first oblique end surface, and the second oblique end surface or the end surface perpendicular to the central axis of the POF; A light shield is installed near the boundary with the first oblique end surface, and at least one of the light from the light emitting element is provided. Is incident on the POF via the second oblique end face or the end face perpendicular to the central axis of the POF, the optical axis of the light receiving element and the light receiving condensing means, and the optical axis of the light emitting element and the light collecting condensing means According to a seventh preferred additional technical means for solving the above-mentioned problem, wherein the second oblique end surface or the second oblique end surface or It is possible to greatly reduce the possibility that reflected light or diffused light at the other part of the POF from the light emitting element installed near the end face perpendicular to the central axis of the POF is incident on the light receiving element. The signal-to-noise ratio of the detected optical signal can be greatly improved, the presence / absence of the detected object can be reliably detected, and the optical signal can be reliably transferred in two-way communication, and can be transmitted by POF. The incident light to the other part of the one end Because it can increase the range of the angle of incidence, there is the advantage that the light emitting element and the light receiving device and an optical transmission and reception system a light emission focusing means it is possible to widen the range of installation can be obtained.

  According to a preferred 8th additional technical means for solving the above-mentioned problem, the POF has a POF aperture conversion portion for converting into a POF having an aperture of 1.5 mm or less or an optical fiber portion in the POF. There is an advantage that the flexibility in the POF or optical fiber portion having a diameter of 1.5 mm or less is further improved, and a low-cost optical transmission / reception apparatus and optical transmission / reception system can be obtained.

The figure which shows the example (slope end surface angle = (delta)) of the optical transmission / reception apparatus and optical transmission / reception system in other embodiment of this invention. Dependence of incident and outgoing light angles satisfying POF transmission conditions on numerical aperture (tilt face angle = 0) The figure which shows the setting example of the optical axis of the incident light and the outgoing light angle which satisfy | fill the POF transmission condition with respect to a bevel end surface angle, and the light-emission condensing means and the optical axis of the light-receiving condensing means (numerical aperture = 0.5, oblique (End face angle = δ, θ = 25 degrees) The figure which shows the structural example of the control apparatus in an optical transmitter / receiver. The figure which shows the example (slope end surface angle = (delta)) of the optical transmission / reception apparatus and optical transmission / reception system in other embodiment of this invention. The figure which shows the example (slope end surface angle = (delta)) of the optical transmission / reception apparatus and optical transmission / reception system in other embodiment of this invention. The figure which shows the example (the oblique end surface angle (light-receiving condensing means side) = δ, the light emission condensing means side oblique end surface angle = δ ′) of the optical transmission / reception apparatus and the optical transmission / reception system in another embodiment of the present invention. In the example of FIG. 7, a diagram showing an incident light / emission light angle range satisfying the POF transmission condition with respect to the light receiving element side oblique end face angle (numerical aperture = 0.5, light receiving element side oblique end face angle = δ, light emitting element side oblique face). (End face angle = δ ', θ = 25 degrees)

FIG. 1 shows an example of an optical transmission / reception device 20 and an optical transmission / reception system 21 according to an embodiment of the present invention. The light emitting element 1, the light emitting condensing means 2, the light receiving element 3, and the light receiving condensing means 4 are arranged near one end 8 of one POF 5, and the object 6 to be detected is moved near the other end 13 of the POF 5. Place. The light emitting element 1 and the light receiving element 3 are controlled by the control device 7. Since it is composed of only one POF 5, there is an advantage that the system configuration is simple and inexpensive, considering the flexibility of the POF portion.
In FIG. 1, one end 8 of POF 5, POF 5, light emitting element 1, light emitting condensing means 2, light receiving element 3, light receiving condensing means 4, and control device 7 constitute an optical transceiver 20.
Further, the optical transceiver 20 includes the other end 13 of the POF 5 and the movable body 6 to constitute an optical transceiver system 21 for detecting a movable body.

One end 8 of the POF 5 is cut obliquely with respect to a plane perpendicular to the central axis 9 of the POF 5 (hereinafter abbreviated as a bevel end surface). The other end 13 of the POF 5 is cut perpendicular to the shaft 9 of the POF 5. The optical axis of the light collecting condensing means 2 has an angle of α degrees with respect to the central axis 9 of the POF 5 or a symmetry plane 22 described later, and the optical axis of the light receiving condensing means 4 is the central axis 9 or symmetrical of the POF 5. It has an angle of β degrees with respect to the plane 22. In all the following descriptions, the clockwise angle is positive, and the counterclockwise angle is negative. Further, in the following explanatory diagrams, for the sake of explanation, the diameter dimension of the POF 5 is shown enlarged as compared with the diameter of the condensing means and the distance between the optical fiber and each condensing means.
In view of the efficiency of light incidence and the flexibility of the POF 5, the diameter dimension of the POF 5 is 1 mm to 10 mm, preferably 1.8 mm to 5 mm. Further, the distance between the oblique end surface of the one end 8 of the POF 5 and the light collecting condensing means 2 or the light receiving condensing means 4 is usually about 1 mm or more and about 15 mm or less, and preferably about POF core diameter or more and 5 times the core diameter. The range is less than about.

In FIG. 1, the end face of one end of the POF 5 is cut obliquely with a slant end face angle of δ from the direction perpendicular to the axis 9 of the POF 5. When the angle formed by the central axis of the outgoing light emitted from the oblique end surface of the light transmitted through the POF 5 with respect to the central axis 9 in the longitudinal direction of the POF 5 is γ (degrees), the relationship of the above formula (1) (hereinafter, Then, “the expression of the central axis of the emitted light” is established. That is, the central axis of the emitted light is bent in a direction farther from the normal direction of the oblique end surface (the sharpest angle portion P side of the oblique end surface described below) with respect to the central axis 9 of the POF 5.
In the following description, the angle formed by the contour line parallel to the central axis 9 of the POF 5 and the oblique end surface portion is lowered from the apex portion P (FIG. 1, abbreviated as the acute angle portion) to the central axis of the POF 5. A plane perpendicular to the vertical line and including the central axis of the POF 5, that is, a plane passing through the central axis of the POF 5 and perpendicular to the paper surface in FIG. Note that Q in FIG. 1 indicates a vertex portion where the angle formed by the outline in the length direction of the POF 5 and the oblique end surface portion has the most obtuse angle.
As described above, the central axis of the outgoing light emitted from the oblique end surface 8 of the POF 5 is bent to the above-described P side with respect to the central axis 9 of the POF 5, so By installing near the central axis (within plus or minus 10 degrees), the emitted light can be detected efficiently, on the side opposite to the optical axis of the light receiving condensing means 4 with respect to the symmetry plane 22, and in the POF 5 Since the optical axis of the light collecting condensing means 2 can be installed within the incident range that satisfies the transmission condition, the light emitting element 1, the light condensing means 2 and the light receiving element are used in a state where the utilization efficiency of incident light and outgoing light is increased. There is an advantage that the element 3 and the light receiving condensing means 4 are easily installed.

Even if the portion where the oblique end surface of the one end 8 of the POF 5 and the optical axis of the light receiving condensing means 4 intersect is slightly located on the opposite side of the light receiving element 3 with respect to the symmetry plane 22, If the main part (90% or more) of the optical axis of the light receiving condensing means 4 between the one end 8 and the light receiving condensing means 4 satisfies the above conditions, there is no particular problem, and the above advantages are preserved. The Similarly, with respect to the optical axis of the light collecting means 4, the main part (90%) of the light axis of the light collecting means 4 between the oblique end surface of the one end 8 of the POF 5 and the light collecting means 2. If the above conditions satisfy the above conditions, there is no particular problem and the above advantages are preserved. Therefore, these states are also included in the description of [0035] above.
Further, the light receiving element 3 and the light receiving condensing means 4, and the light emitting element 1 and the light emitting condensing means 2 can be located on the opposite side with respect to the symmetry plane 22 and can be installed almost symmetrically. By using a commercially available reflective photosensor 11, the conventional method does not require a troublesome setting of the optical axis, and it is possible to easily set a state of high light utilization efficiency and to easily construct a system with uniform characteristics. There are advantages.

  Note that a collimating lens that condenses light from the light emitting element 1 and converts it into substantially parallel light can be used as the light emission condensing means 2 instead of a normal lens. Since most of the light input to the collimating lens can be incident from one end of the POF 5 under conditions that satisfy the transmission conditions in the POF 5, there is an advantage that the amount of light incident on the light receiving element 3 is further increased. In addition, when a collimating lens is used as the light receiving condensing means, only the emitted light at a predetermined angle from the POF 5 can be condensed, so that the light incident on the end face of the one end 8 of the POF 5 from the light emitting condensing means There is an advantage that it is difficult to receive the direct reflected light.

FIG. 2 shows the condition of the angle of incident light on the POF 5 and the light emitted from the POF 5 under the condition that the POF 5 can be transmitted through the POF 5 when one end of the POF 5 is cut perpendicular to the axis 9 of the POF 5. Indicates the range of light angles. When the end 8 of the POF 5 has a beveled end surface, the light existence range slightly increases with respect to the central axis of the emitted light or incident light, but the basic tendency remains the same.
In order for the light receiving element 3 to detect light from the detected object 6 efficiently and stably, the optical axis of the light collecting condensing means 2 and the optical axis of the light receiving condensing means 4 are emitted from at least the POF 5. It should be installed within an angle where there is light. That is, in FIG. 2, it is necessary to set the optical axis of the light receiving condensing means 4 in the range of the gray portion where the outgoing light exists.

  It is not impossible to arbitrarily design the relationship between the optical axis of the light collecting condensing means 2 and the optical axis of the light receiving condensing means 4. However, in order to make a significant part of the light from the light emitting element 1 enter the POF 5 and to make a considerable part of the light emitted from the POF 5 enter the light receiving element 3, the light collecting condensing means 2 and the light receiving condensing means. The means 4 requires a certain size, and is an angle (hereinafter abbreviated as θ. | Α−β |) formed by the optical axis of the light collecting condensing means 2 and the optical axis of the light receiving condensing means 4. It has been found that it takes at least about 15 degrees to use a general-purpose light-receiving element, light-emitting element, reflection type photosensor, or the like. As a preferable condition that the light directly reflected from the end face of the POF 5 of the light from the light-collecting light collecting unit 2 is less likely to be incident on the light-receiving light condensing unit 4, the optical axis of the light-emitting light collecting unit 2 or the light collecting light collecting When the optical axis of the means 4 is substantially coincident with the axis 9 of the POF 5, the numerical aperture of the optical fiber 5 that satisfies the above two conditions is about 0.3 or more from FIG.

Note that a part of the light incident on the end face of the POF 5 is directly reflected, but a part of the direct reflected light may become diffusive reflection depending on the unevenness and surface state of the end face part. In order to reduce the unnecessary light incident on the light receiving element 3 and increase the amount of light incident on the light receiving condensing means 4 even if there is diffusive reflection in this way, It has been found that the angle θ formed by the optical axis and the optical axis of the light receiving condensing means 4 is preferably about 20 degrees or more. In this case, the numerical aperture of the POF 5 is preferably about 0.4 or more from FIG.
On the other hand, when the numerical aperture is 0.7 or more, the light emitted from the POF 5 spreads too much to reduce the amount of light per unit solid angle, which is not preferable because the amount of light incident on the light receiving element also decreases. Therefore, the numerical aperture is set to 0.7 or less, more preferably 0.6 or less.

  In FIG. 1, the light directly reflected from the oblique end surface of the one end 8 of the POF 5 of the light from the light emitting element 1 is reflected in the light emission condensing means 2 or the vicinity thereof, or the oblique end surface of the one end 8 of the POF 5 is reflected. The optical axis of the light-emission condensing means 2 is within plus or minus 10 degrees in the normal direction of the oblique end surface of the one end 8 of the POF 5 so that it is reflected to the opposite side to the light-receiving condensing means 4 with respect to the normal line. Or, it is installed on the light receiving condensing means 4 side with respect to the normal direction of the oblique end surface of the one end 8 of the POF 5.

FIG. 3 shows the incident light incident on the oblique section satisfying the transmission condition in the optical fiber 5 with respect to the oblique axis angle δ when the aperture angle is 0.5, the central axis of the emitted light, the normal direction of the oblique face angle. The range of the angle α (degrees) with respect to the POF5 axis and the range of the angle β (degrees) of the incident light from the oblique section with respect to the POF5 axis are shown in gray. In addition,
| Α (degrees) −δ (degrees) | ≧ 90, or | β (degrees) −δ (degrees) | ≧ 90 In the case of Equation (2), the incident light enters or exits the POF 5. It becomes impossible. In FIG. 7, the case of the equal sign in equation (2) is abbreviated as | α, β−δ | = 90.
Further, in the case of 90> | α, β−δ | ≧ 80, the angle between the incident or outgoing light and the end face of the oblique section is 10 degrees or less, and the solid angle for looking at the end face of the POF 5 becomes extremely narrow. It is difficult to receive incident light and to receive outgoing light.

  Note that the transmission conditions with respect to the oblique end face angle when the numerical aperture is other than 0.5 show a tendency similar to that in FIG. That is, the width of the existing range of incident light and outgoing light existing above and below the central axis of the outgoing light is the same as the width of the existing range in FIG. Increases with increasing value.

  In FIG. 3, when the angle formed by the optical axis of the light collecting condensing means 2 and the optical axis of the light receiving condensing means 4 = θ (degrees) = | α−β | An angle formed by the optical axis of the light collecting condensing means with respect to the central axis 9 or symmetrical plane 22 of the POF 5 is indicated by a black circle, and the optical axis of the light receiving condensing means is the central axis 9 or symmetrical plane of the POF 5. An angle formed with respect to 22 = β (degrees) is indicated by a vertex of an arrow, and a case number is given to a black circle portion.

When the oblique end face angle δ is 0 (that is, when the end face is perpendicular to the central axis of the POF 5), A0, A1, and A2 in FIG. 3 can be set. In both A0 and A1, the optical axis of the light collecting condensing means is installed near the central axis of the POF 5, and the optical axis of the light receiving condensing means is installed near the limit of the existing range of incident light and outgoing light. . In these cases, there is a drawback that the amount of light incident on the light receiving element is significantly reduced.
On the other hand, in A2, the optical axis of the light-collecting condensing means is installed near the limit of the existence range of incident light and outgoing light, and the optical axis of the light-receiving condensing means is installed near the central axis of POF5. In these cases, the amount of light to the light receiving element is increased, but the optical axis of the light-emission condensing means is installed near the limit of the existence range of incident light and outgoing light, and the optical portion of the optical axis component outside this limit is POF5 In order to allow a predetermined amount of light to be incident on the POF 5, it is necessary to install the optical axis of the light-emission condensing means with high accuracy, resulting in an increase in cost and the amount of light transmitted through the POF 5. There are downsides.

In the vicinity of the oblique end face angle δ = 5 degrees, the B0 case having a black circle in the normal direction of the oblique end face of the one end 8 of the POF 5 and the apex of the arrow at minus 20 degrees in the opposite normal direction from the central axis of the emitted light is δ Compared to the A0 case with = 0, the light receiving amount increases because the optical axis of the light receiving condensing means approaches the central axis of the outgoing light, but the light receiving portion is within ± 10 degrees of the central axis of the outgoing light. The value is lower than that in the case of setting the optical axis of the light collecting means. In the case of B2 in which a black circle is set in a direction normal to the central axis of the outgoing light and the vertex of the arrow is on the central axis of the outgoing light, the direct reflected light at the oblique end surface of the one end 8 of the POF 5 of the incident light is Reflected at a position symmetrical with respect to the normal direction 10 of the oblique end surface of the end 8 of the POF 5 and further away from the optical axis of the light receiving condensing means, it is symmetric with respect to the central axis of the POF 5 of the A1 case where δ = 0. The risk of receiving unnecessary light is further reduced as compared with a case (referred to as A2 case). However, it has the same defects as described in the case of A2 when δ = 0.
In the B1 case in which the black circle is placed on the side opposite to the light receiving element from the normal direction 10 of the end face 8 of the POF 5 and the vertex of the arrow is set as the central axis of the emitted light, the incident light at the oblique end face of the one end 8 of the POF 5 Since the directly reflected light approaches the optical axis of the light receiving condensing means 4, it is not preferable.

In the vicinity of the bevel end face angle δ = 10 degrees, the C0 case having a black circle in the normal direction of the bevel end face of the one end 8 of the POF 5 and the vertex of the arrow in the central axis direction of the emitted light is compared with the B0 case of δ = 5 degrees. Since the optical axis of the light receiving condensing means is within or near plus or minus 10 degrees of the central axis of the emitted light, the amount of received light is further increased.
The case of C2 having a black circle in a direction opposite to the central axis of the outgoing light and having the vertex of the arrow on the central axis of the outgoing light has a higher risk of receiving unnecessary light than the B2 case of δ = 5 degrees. However, it has the same drawbacks as described in the case of A2 when δ = 0.
In the C1 case in which the black circle is placed on the side opposite to the light receiving element from the normal direction of the end face of the optical fiber 5 and the vertex of the arrow is set as the central axis of the outgoing light, the incident light at the oblique end face of the one end 8 of the POF 5 Since the directly reflected light approaches the optical axis of the light receiving condensing means, it is not preferable as in the case B1.

In the vicinity of the oblique end face angle δ = 20 degrees, a black circle is set on the center axis side of the outgoing light from the normal direction of the oblique end face of the one end 8 of the POF 5 and the vertex of the arrow is set near the central axis of the outgoing light. Since the direct reflected light of the incident light at the oblique end surface of the one end 8 of the POF 5 is further away from the optical axis of the light receiving condensing means, unnecessary light is received compared to the C0 case where δ = 10 degrees. The risk is further reduced. In addition, since the arrow can be matched to the vicinity of the central axis of the emitted light, the amount of received light increases and the SN ratio increases.
The case of D2 in which a black circle is set in a direction opposite to the normal axis of the outgoing light and the vertex of the arrow is on the central axis of the outgoing light has the same drawbacks as those described in the case of A2 when δ = 0. In addition, the disadvantage of narrowing the angle at which the oblique end surface is viewed from the optical axis of the light-collecting means becomes stronger.

In the vicinity of the oblique end face angle δ = 30 degrees, the cases F1 and F2 have similar characteristics to the cases D1 and D2 when δ = 20 degrees. The case of D1 in which a black circle is set on the central axis side of the outgoing light with respect to the normal direction 10 of the end face of the one end 8 of the optical fiber and the vertex of the arrow is set near the central axis of the outgoing light is one end of the POF 5 of the incident light. Since the directly reflected light at the oblique end surface 8 is further away from the optical axis of the light receiving condensing means, the risk of receiving unnecessary light is further reduced compared to the D0 case where δ = 20 degrees. In addition, since the arrow can be matched to the vicinity of the central axis of the emitted light, the amount of received light increases and the SN ratio increases.
When θ = 25 degrees, there are places where the black circle and the arrow are symmetrical with respect to the central axis 9 of the POF 5 near 20 degrees ≦ δ ≦ 30 degrees (E1). This portion has an advantage that it is easy to set the light-emitting element 1, the light-collecting condensing means 2, the light-receiving element 3, and the light-receiving condensing means 4 when actually performing optical settings.

In the G1 case near the oblique end face angle δ = 40 degrees, light incident on the other end 13 of the POF 5 from the object to be detected is transmitted through the fiber and emitted from one end 8 of the POF 5, but the end face of the one end 8 of the POF 5 is oblique. Therefore, the emitted light is refracted in a direction away from the normal direction of the oblique end surface. For this reason, since the angle θ between the optical axis of the light-emission condensing means 2 and the light-receiving condensing means 4 can be increased as compared with the case where the end face of the POF 5 is perpendicular to the optical axis of the POF 5, Depending on the state, even if a part of the direct reflected light becomes diffusive reflection, the unnecessary light incident on the light receiving element 3 can be greatly reduced. In addition, since the optical axis of the light receiving condensing means 4 can coincide with or be close to the central axis of the outgoing light emitted from one end of the POF 5, the amount of light incident on the light receiving element can be greatly increased. For this reason, there is an advantage that a measurement with a much improved SN ratio becomes possible.
However, as shown in FIG. 3, the position of the central axis of the emitted light from the one end 8 of the POF 5 greatly changes with a slight increase / decrease in the oblique section angle. It is necessary to accurately manage the oblique section angle.

If the oblique end face angle δ in FIG. 3 is too large, the transmission condition of POF 5 will not be satisfied, the position of the central axis of the emitted light will change greatly with a slight increase or decrease in the oblique section angle, or the normal direction of the oblique end face And the central axis direction of the light emitted from the optical fiber 5 becomes wider than necessary, and the effect of the oblique end face angle δ is reduced. Therefore, the oblique end face angle δ is 5 degrees or more and 40 degrees or less, preferably Set to 10 degrees or more and 40 degrees or less.
In FIG. 3, as the position of the arrow, if the portion matched with the central axis of the outgoing light is within plus or minus 10 degrees of the central axis of the outgoing light, the amount of light in the outgoing light is relatively large. Since the portion is input to the light receiving element 3, the same effect as described above can be obtained. In this case, the range of δ in which the black circle and the arrow described in [0049] are symmetrical with respect to the central axis 9 of the POF 5 is expanded to near 13 degrees ≦ δ ≦ 30 degrees.
3 illustrates the case where the angle θ between the black circle and the arrow is 25 degrees, but as described above, the present invention can be applied if it is 15 degrees or more, and preferably 20 degrees. Any degree or more is acceptable. If the angle θ between the black circle and the arrow is too large, as expected from the tendency of FIG. 2, as expected from the tendency of FIG. 2, the POF 5 that can be used to prevent unnecessary reflected light on the oblique end surface of the end 8 of the POF 5 as much as possible. Since the numerical aperture is limited to a large one, the angle θ between the black circle and the arrow is 50 degrees or less, preferably 40 degrees or less.

  FIG. 4 shows a configuration example of the control device 7. In response to the pulse signal from the synchronizing signal generating means 7-2, the light emitting element driving means 7-3 causes the optical element 1 to periodically emit light, and the light emission condensing means 2 introduces light to one end 8 of the POF 5. . Transmits through the POF 5, emits light from the other end 13 of the POF 5, reenters at least a part of the other end 13 of the POF 5, transmits through the POF 5, and radiates from the one end 8 of the POF 5. Light is converted into electricity by the light receiving element 3 via the light means 4. The signal is amplified by the signal amplifying means 7-4, converted into a digital signal by the AD converting means (analog-digital converter) 7-5 by the conversion start pulse signal from the synchronizing signal generating means 7-2, and then the signal The signal is processed by the processing means 7-1 and output to the output signal 12 or the display 7-8. The collected data is stored in the temporary storage means 7-6. The output signal 12 may be a contact output via a relay element or the like. The instruction to the signal processing means 7-1 is given from the input means 7-7 by a switch or a touch panel. The signal processing means 7-1, synchronization signal generating means 7-2, AD converting means 7-5, temporary storage means 7-6, etc. are commercially available general-purpose microcomputers (for example, PIC) as the processing device 7-9. Can be substituted. The AD conversion means 7-5 can include a sample and hold circuit function as required. Further, when a microcomputer or a digital signal processing device is used for other processing, a part of the functions of the microcomputer or the digital signal processing device is used, and the processing device 7-9 in FIG. You can also perform functions.

In the present invention using a single fiber, depending on the state of the end face at one end 8 of the POF 5, the light emitted from the light emitting element 1 is partially reflected and diffused at the one end 8 or the other end 13 of the POF 5. The risk of being input to the light receiving element 3 is high. By manufacturing the end face of the one end 8 in an oblique cross section, the risk of unnecessary light being input to the light receiving element 3 can be greatly reduced, but it is difficult to make it zero. Therefore, among the light amount input to the light receiving element 3, the signal component resulting from the light emitted from the optical element 1 reentering the optical fiber 5 from the other end of the optical fiber 5 via the detected object 6 and the one end 8 of the POF 5. It is necessary to discriminate between the unnecessary light quantity caused by the light reflected and diffused by the end face of the other end 13 and the other unnecessary light quantity origin.
In the conventional system using another optical fiber or another optical fiber portion, the light emitting optical element 1 is introduced into the optical fiber and the light is emitted from the optical fiber to the light receiving element 3. The reception of unnecessary light due to the light reflected and diffused at the end face of 8 does not normally need to be considered.

In the present invention, the light reflected and diffused from the optical element 1 at the end face such as the one end 8 or the other end 13 of the POF 5 is highly required to grasp unnecessary light incident on the light receiving element 3. Since this unnecessary light also changes depending on the state of the end face such as one end 8 or the other end 13 of the POF 5, it is measured at an appropriate period and the value (hereinafter abbreviated as data due to fiber end face reflection etc.) is temporarily stored. It is preferable to store the data in the storage means 7-6 and, in normal times, first subtract the data due to the fiber end face reflection from the measurement data, and then perform subsequent signal processing. The fiber end surface reflection-related data includes other unnecessary light amount-related components described above, including reflection at a POF aperture converter 5-2, which will be described later.
The timing for measuring the fiber end face reflection data is performed when the detected object 6 is away from the other end 13 of the POF 5. In the single-core bidirectional communication system to be described later, the communication is performed in a state where communication is not performed and the light emitting element is emitting light. In the initial state, in the case where the detected object 6 is separated from the other end 13 of the POF 5 or the case where communication is not performed, the detection can be performed immediately after the power is turned on. Further, a reset position TEST switch is provided in the input means 7-7 so that the operator confirms that the detected body 6 is separated from the other end 13 of the POF 5 or performs communication in a single-core bidirectional communication system. It may be performed when the operator confirms that there is no such event and the operator presses this switch.

  By manufacturing the end face of the one end 8 of the POF 5 in the form of a slant end face, unnecessary light caused by fiber end face reflection or the like input to the light receiving element 3 can be greatly reduced. In this case, the values of a plurality of data whose values after AD conversion are equal to or less than a predetermined value are time-averaged, and the values are stored in the temporary storage means 7-6 at an appropriate period, and the values are reflected on the above-mentioned fiber end face reflection. It can also be used as equivalence data.

  As described above, if the data resulting from reflection at the fiber end face is first subtracted from the data after AD conversion in normal time and then the subsequent signal processing including threshold processing is performed, the data at the time of signal processing is unnecessary. Since a value due to a large amount of light can be eliminated, it is possible to distinguish not only binary measurement of the presence / absence of the detected object 6 but also multi-value of a plurality of gradations. For example, as the relative position between the detection object 6 and the POF 5, it is possible to determine a multi-value of three or more values, such as four steps of the latest, a little closer, a little far, and a far.

Further, by combining a plurality of light emitting elements 1 having different emission spectra (for example, red, green, blue, etc.) and a plurality of these POFs 5 and a plurality of light receiving elements 3 respectively, Detection is also possible. In this case, it can be configured simply by arranging a plurality of systems shown in FIG. The portion surrounded by the dotted line in the control device 7 can be processed in sequence by a single microcomputer with an analog multiplexer, and the input means 7-7 and the display means 7-8 are also a set. When multi-valued determination of three values or more is performed with respect to light emission of three colors, it is possible to determine colors exceeding 10 colors.
If a plurality of light emitting elements having different emission spectra are integrated as one light emitting element 1 and a plurality of light receiving elements having different light reception spectra are integrated as one light receiving element 3, a single light emitting element 1 is used. The color information of the detection object 6 can be detected with a very simple configuration using only one POF 5. Further, a plurality of light emitting elements having different emission spectra are integrated as a single light emitting element 1, and a plurality of light emitting elements incorporated in the light emitting element 1 are turned on in a time-sharing manner, so that a single light having a wide light receiving spectrum is obtained. Even when color information is detected in synchronization with light emission using the light receiving element 3, the color information of the detection target 6 can be detected with a very simple configuration using only a single POF 5.

  In the case of ternary or higher multilevel determination, it is preferable to calibrate the maximum light amount to the light receiving element 3 using a white detection object. Actually, a white object to be detected having a high reflectance is placed near the other end of the POF 5, and the maximum light amount calibration button provided in the input means 7-7 is pressed, so that it enters the light receiving element 3 at this time. The optical signal is AD-converted via the signal amplifying means 7-4, and the above-mentioned data caused by reflection of the fiber end face is subtracted from the value at this time, and the maximum light quantity signal is stored in the temporary storage means 7-6 in the control section 7. Remember. The area between zero and the value of the maximum light quantity signal is divided into three or more areas. In the case of ternary values, it is divided into a non-reflection area, a small reflection area, a mid-reflection area, and a large reflection area. This division may be equally spaced, or the portion where the reflected light is weak may be narrowed and the strong portion may be widened to match the sense of the human eye.

  Until now, in FIG. 1, the POF 5 is arranged in a straight line, but it goes without saying that the present invention can be similarly applied even if it is bent within a range in which the transmission conditions in the POF 5 do not change significantly. When the light emission direction at the other end 13 of the POF 5 and the position of the detected object 6 do not intersect, an optical adapter 14 (not shown) that changes the light emission direction is used at the other end 13 portion of the POF 5. However, the present invention can be similarly applied. The optical adapter 14 may be a bent fiber, a reflection mirror, a prism, or the like.

  In addition, the aperture is converted into a small aperture POF by the same method as the aperture conversion means described later, the aperture in the vicinity of the other end 13 of the POF 5 is narrowed, and the region of the emitted light emitted from the other end 13 of the POF 5 is limited to a narrow range. In addition, it is possible to configure an optical transmission / reception system for detecting a moving body with high positional accuracy.

  FIG. 5 shows another embodiment. Up to now, the case where a POF 5 having a single diameter is used as the POF 5 has been described. However, the present invention is not limited to this. As shown in FIG. 5, a relatively large diameter with an end face processed obliquely. The POF portion 5-1 (for example, the diameter is 1.8 mm-5 mm), the POF portion 5-3 that is a thin diameter (for example, 0.2 mm-1.5 mm), and the POF aperture whose diameter changes between them is changed. It consists of the conversion unit 5-2.

In FIG. 5, the light emitting element 1, the light receiving element 2, the light emitting condensing means 2, and the light receiving condensing means 4 are shown in the case where an integrated reflection type photosensor 11 is used. The integrated reflection type photosensor 11 is also available on the market, and has the advantage of being low in cost and quality.
Further, a light shielding means 16 is installed in the vicinity of the integrated reflection type photosensor 11 portion and one end 8 of the POF 5-1 so that external light is not incident on the end surfaces of the light receiving element 3 and the POF 5-1. . In addition, it is preferable that the inner surface of the light shielding means 16 is coated with a matte black paint or the like so that unnecessary reflection does not occur.
In FIG. 5, the oblique end surface of the one end 8 of the POF 5 is processed obliquely at an oblique section angle δ = 10−40 degrees, preferably 15 degrees−30 degrees. The angle α formed between the central axis 9 or the symmetry plane 22 of the POF 5 and the optical axis of the light collecting means 2 is set to +5 degrees or +30 degrees (preferably +5 degrees or +20 degrees), and the central axis 9 or The angle β formed between the symmetry plane 22 and the optical axis of the light receiving condensing means 4 is set to −5 degrees or −30 degrees (preferably −10 degrees or −20 degrees).
As described with reference to FIG. 3, if the oblique section angle δ is set to an appropriate value of about 13 degrees to 30 degrees in accordance with the integrated reflection type photosensor 11 to be used, the above angle α And β have opposite signs and can be set to substantially the same absolute value, so that there is an advantage that the optical setting is facilitated.

At the end 8 of the POF 5 that inputs and outputs light through the light collecting means 2 and 4 between the light emitting element 1 and the light receiving element 3, as shown in FIG. The light can be input and output more efficiently when using. In addition, using a POF 5-1 having a relatively large diameter (for example, a diameter of 1.8 mm-5 mm) allows light to be efficiently incident on the POF 5 even if the optical axis is slightly shifted. The light emitted from the light can be received without greatly changing. However, when the diameter of the fiber is increased, the flexibility is deteriorated and the bending radius is increased.
On the other hand, the other end 13 of the POF 5 for which a change in reflected light is to be detected often requires a small installation space or a small optical fiber bending radius, and the diameter near the other end 13 of the POF 5 is preferably narrower. There are many cases. In such a case, as shown in FIG. 5, a portion that gradually changes the diameter of the POF 5 may be provided in the middle of the POF 5, such as the POF aperture conversion unit 5-2.

  The POF aperture conversion unit 5-2 can be obtained by gradually pulling an optical fiber having a relatively large diameter while applying heat from the surroundings while rotating the optical fiber having a relatively large diameter. Alternatively, the vicinity of the tip of an optical fiber having a relatively large diameter may be machined so as to have a tapered shape as shown in the POF aperture converter 5-2 in FIG. 5, and the tip may be bonded to an optical fiber having a small diameter. In this case, it is desirable to use an adhesive having a refractive index close to that of the POF core after fixing, and the machined portion is made of a single layer or a plurality of layers with a low refractive index resin of transparent fluororesin in advance. It is desirable to form a thin single layer or a plurality of clad layers.

  As the POF aperture converting section 5-2, a lens or a substance having a lens action as described or cited in JP-A-2001-350037 is used, or the end surface of the POF 5 on the large aperture side is processed into a convex shape. It is also possible to use a method for efficiently converting the aperture of the POF 5 by, for example.

  Note that, regardless of which POF aperture converter 5-2 is used, some reflection components are generated in the POF aperture converter 5-2, part of which is transmitted through the POF 5 in reverse and emitted from one end 8 of the POF 5, It is detected as unnecessary light by the light receiving element 3. For this reason, when the POF aperture converter 5-2 is used, the signal processing of the fiber end surface reflection and the like data described with reference to FIG.

  In FIG. 5, the light from the light emitting element 1 irradiates the edge part of the end face of the POF 5 and the light shielding means 16 by appropriately condensing the light collecting means 2 and condensing only on a part of the oblique end face 8 of the POF 5. Thus, it is possible to avoid or significantly reduce the unnecessary reflected light from entering the light receiving element 4. A light shield 19 as described later is provided between the light condensing means 2 and the POF 5 so as to limit the light from the light emitting element 1, and the light from the light emitting element 1 is incident on the end face of the POF 5 on the light receiving element 3 side. It is also possible to configure so as not to irradiate the edge or the like, and to prevent the unnecessary reflected light from entering the light receiving element 4.

FIG. 6 shows another embodiment of an optical transmission / reception system in which integrated reflection type photosensors 11a and 11b are installed at both ends of POF 5 and data communication is performed between personal computers 17a and 17b via control devices 7a and 7b. An example is shown. The electric communication paths 12a and 12b can be adapted to low-speed RS-232C standard communication and higher-speed full-duplex communication.
The signal transmitted from the first personal computer 17a drives the light emitting element 1a via the control device 7a. The light is incident on one end of the POF 5 through the issuing condensing means 2a. The incident light propagates through the optical fiber 5, is emitted from the other end of the optical fiber 5, enters the light receiving element 3b via the light receiving condensing means 4b, is converted into an electric signal, and is then controlled by the control device 7b. To the second personal computer 17b via the electric communication path 12b.
Similarly, the signal transmitted from the second personal computer 17b follows the reverse route and is input to the first personal computer 17a. In the POF 5, a wave propagating to the right and a wave propagating to the left coexist, but basically no interference or the like occurs between the light in both directions.
FIG. 6 shows an optical transmission / reception system 21 for single-core bi-directional communication in which the aperture converters 5-2a and 5-2b are provided in the POF 5 portion, and the aperture of the main portion of the POF 5 is narrowed to improve flexibility.
The light emitting elements 1a and 1b have different emission wavelengths, and an optical filter that allows light from the light emitting element 1a to pass but does not pass light from the light emitting element 1b is disposed on the front surface of the light receiving element 3b or its condensing means 4b. By installing an optical filter that allows light of 1b but not light of the light emitting element 1a on the front surface of the light receiving element 3a or its condensing means 4a, it is possible to receive unnecessary light via the end face or edge of the POF 5 or the light shielding means 16. The adverse effect of leakage into the element 3 can also be reduced.

  In FIG. 6, the POF 5 can be attached / detached using the optical connector 15. In FIG. 6, it is desirable to install optical connectors 15a and 15b (not shown) in the 5-1a and 5-1b portions, which are POF portions having a large aperture, without requiring much optical connector joining accuracy. Since the bonding characteristics can be obtained, it is preferable in terms of cost and performance.

FIG. 7 shows an example of an optical transmission / reception device 20 in which one end 8 of the POF 5 is constituted by a plurality of end faces. The oblique end face angle δ of the end face (first end face portion) facing the light receiving condensing means 4 is set to plus, and the oblique end face angle δ of the end face (second end face portion) facing the light emitting condensing means 2 is set. '(See FIG. 7) is set to 0 or minus, the light emitted from the POF 5 is efficiently detected, the incident efficiency to the POF 5 is improved, and unnecessary light from the light emitting element 1 is not incident on the light receiving element 3 It is configured as follows.
In this case, as described with reference to FIG. 1, the central axis of the outgoing light emitted from the oblique end surface of the one end 8 of the POF 5 is bent to the P side with respect to the central axis 9 of the POF 5. By arranging the optical axis 4 near the central axis of the outgoing light (within ± 10 degrees), the outgoing light can be detected efficiently, and the optical axis of the light receiving condensing means 4 with respect to the symmetrical plane 22 Since the optical axis of the light-collecting light collecting means 2 can be installed on the opposite side and in an incidentable range that satisfies the transmission conditions in the POF 5, the light-emitting element 1, the light-emitting light collecting means 2, the light-receiving element 3, and the light-receiving light collecting means 4 is easy to install, and there is an advantage that a commercially available integrated reflection type photosensor can be used.
When the distance between the centers of the light-emission condensing means 2 and the light-receiving condensing means 4 in the integrated reflective photosensor 11 is equal to or wider than the diameter of the POF at one end 8 of the POF 5, The oblique end face angle δ of the end face (second end face portion) facing the light-collecting means 2 is set to be positive by setting the oblique end face angle δ of the end face (first end face portion) facing the light collecting means 4 to be plus. 7) is set to 0 or minus, and the incident light to the POF 5 and the outgoing light from the optical fiber 5 are efficiently input / output to / from the integrated reflection type photosensor 11.
In order to avoid unnecessary light from being incident on the light receiving element 3 due to unnecessary reflected light from the end face of the POF 5 or the light shielding means 16 due to light from the light emitting element 1, the first end face part, the second end face part, A light shielding body 19 is provided between the boundary portion of the light source and the integrated reflective photosensor 11. Further, by providing the gap 18 in the end surface portion of the boundary portion between the first end surface portion and the second end surface portion, unnecessary light through this boundary portion can be greatly reduced.
As a result, it is possible to greatly reduce the risk that unnecessary reflected light from the one end 8 of the POF 5 is incident on the light receiving element 3 due to the light from the light emitting element 1, and the optical axis of the light collecting means 2. The installation range of can be greatly increased. That is, in FIG. 4, it is not necessary to limit the light emitting element to be installed on the light receiving element side from near the normal direction of the fiber end face.

The contour line in the length direction of the POF 5 and the sharpest corners of the first end face part and the second end face part are indicated by P and P ′.
The plane perpendicular to the central axis of the POF 5 from P, which is the sharpest corner of the first end face portion, and including the central axis of the POF 5, that is, the plane that passes through the central axis of the POF 5 in FIG. Is called a plane of symmetry 22 as in FIG.

FIG. 8 shows the range of emitted light and the possible range of incident light that satisfy the transmission conditions in POF 5 with respect to FIG. Note that the black circles and arrows in FIG. 8 are the same as those used for the explanation of FIG.
In FIG. 8, the negative part of the vertical axis indicates the range of the emitted light from the first end face of the one end 8 of the POF 5, and this range corresponds to the lower half of FIG.
In FIG. 8, the vertical axis indicates a possible range of incident light on the second end face portion of the one end 8 of the POF 5. In this case, it becomes irrelevant to the oblique section angle (δ) of the first end face, and depends only on the oblique section angle (δ ′) of the second end face. When δ ′ = 0, the upper limit of β is about 30 degrees, and when δ ′ = 10 degrees, the upper limit of β is about 37 degrees, and the oblique section angle (δ ′) of the second end face increases. , Β also increases.
Further, even if light from the light emitting element 1 is incident on the second end face of the one end 8 of the POF 5 and a reflection component is generated at the end face, it is shielded by the light shielding means 19 and is not input to the light receiving element 3. There is an advantage that a signal with a high S / N ratio can be received even in the case of 3 of B1 and C1.

1: light-emitting element, 2: light-collecting means, 2 ′: light-emitting collimator lens,
3: light receiving element, 4: light receiving condensing means, 4 ′: light receiving collimator lens,
5: POF, 6: detected object, 7: control device, 8: one end of POF,
9: POF central axis, 10: normal line of one end face of POF, 11: integrated reflection type photosensor, 12: output signal of control device, 13: other end of POF, 14: optical adapter, 15: light Connector: 16: light shielding means, 17: personal computer, 18: air gap, 19: light shielding body, 20: optical transceiver, 21: optical transceiver system, 22: plane of symmetry

Claims (11)

  At least part of one end of a single POF having a numerical aperture of 0.4 to 0.6 and a core diameter of 1.8 mm to 5 mm is 10 degrees from a plane perpendicular to the central axis of the POF. It is composed of a beveled end surface having an angle of 40 degrees or less, and is perpendicular to the perpendicular line drawn from the sharpest portion between the outline of the POF parallel to the central axis of the POF and the oblique end surface to the central axis of the POF and the POF The optical axis of the light receiving element and the light collecting condensing means on the most acute angle portion side, and the light axis of the light emitting element and the light collecting condensing means on the opposite side to the sharpest angle portion with respect to the plane including the central axis of And at least part of the light from the light emitting element is incident on the POF, the light emitted from the POF is detected by the light receiving element via the light receiving condensing means, and the output is passed through the AD converter, Input signal processing device with threshold processing, signal processing Optical transceiver using a single POF, characterized in that the output from the signal processing apparatus.   The optical axis of the condensing means for receiving light is set within plus or minus 10 degrees of the central axis of the light emitted from the oblique end surface of the POF, and the optical axis of the condensing means for emitting light is transmitted through the POF. The light source condensing means is installed in a position that does not enter the light receiving condensing means within a range that satisfies a condition and that directly reflects light at the cut surface of the one end of the POF from the light emitting condensing means. 2. An optical transmission / reception apparatus using the single POF described in 1.   The optical axis of the light collecting condensing means is set within plus or minus 10 degrees of the normal direction of the oblique end face of the POF or on the light receiving condensing means side with respect to the normal direction of the oblique end face of the POF. The single POF according to claim 1 or 2, wherein the optical axis of the light receiving condensing means is set within a range where the light emitted from the one end of the optical fiber exists. The optical transceiver used.   A part of one end of one POF is constituted by a first oblique end surface having an angle of not less than 10 degrees and not more than 40 degrees from a plane perpendicular to the central axis of the POF, and the POF parallel to the central axis of the POF A light receiving element and a light receiving collector are disposed on the side of the acute angle portion with respect to a plane perpendicular to the perpendicular line extending from the sharpest portion of the outline and the first oblique end surface to the central axis of the POF and including the central axis of the POF. The optical axis of the light means is arranged on the side opposite to the sharpest angle portion, the light axis of the light emitting element and the light collecting condensing means, and the first oblique end surface with respect to a plane perpendicular to the central axis of the POF A second oblique end surface having an opposite angle or an end surface perpendicular to the central axis of the POF, and a boundary between the second oblique end surface or the end surface perpendicular to the central axis of the POF and the first oblique end surface A light-shielding body is installed in the vicinity, and at least part of the light from the light-emitting element is supplied to the second oblique end surface or the P The light is incident on the POF via the end face perpendicular to the central axis of F, and light emitted from the first oblique end face of the POF is detected by the light receiving element via the light receiving condensing means. An optical transceiver using the single POF according to claim 1.   5. An optical transmission / reception using a single POF according to claim 1, wherein a light emitting element, a light collecting condensing means, a light receiving element, and a light receiving condensing means are integrated. apparatus.   Use a signal processing device that stores the received light amount signal immediately after power-on or during a predetermined operation, and normally performs signal processing including threshold processing after subtracting the stored received light amount signal from the received light amount signal. An optical transmission / reception apparatus using a single POF according to claim 1 or 4, characterized in that:   The received light amount signal when the received light amount signal is equal to or less than a predetermined value is averaged and stored, and in normal times, after the stored received light amount signal is subtracted from the received light amount signal, signal processing including threshold processing is performed. An optical transceiver using a single POF according to claim 1 or 4. A light emitting element, a light emitting condensing means, a light receiving element, and a light receiving condensing means are arranged near one end of one POF, and the POF is irradiated again with light emitted from the other end of the POF, and then again the POF. An optical transmission / reception system arranged to be incident on
At least part of one end of the POF having a numerical aperture of 0.4 to 0.6 and a core portion having a diameter of 1.8 mm to 5 mm is at least 10 degrees from a plane perpendicular to the central axis of the POF. A slanted end surface having an angle of 40 degrees or less, perpendicular to a perpendicular line extending from the sharpest part of the slanted end surface and the outline of the POF parallel to the central axis of the POF to the central axis of the POF, and the With respect to a plane including the central axis of the POF, the optical axis of the light receiving element and the light collecting condensing means is on the most acute angle portion side, and the light axis of the light emitting element and the light emitting condensing means is on the opposite side of the sharpest angle portion. And at least a part of the light from the light emitting element is incident on the POF and the light emitted from the POF is detected by the light receiving element through the light receiving condensing means, and the output is passed through the AD converter. And input to a signal processing device having threshold processing. Optical transmission and reception system using a single POF, characterized in that the output from the signal processing device after processing. A first light emitting element, a first light emitting condensing means, a first light receiving element, and a first light receiving condensing means are arranged near one end of one POF, and near the other end of the POF, An optical transmission / reception system in which a second light emitting element, a second light emitting condensing means, a second light receiving element, and a second light receiving condensing means are arranged to perform single-core bidirectional communication,
At least a part of each of the one end and the other end of the POF having a numerical aperture of 0.4 to 0.6 and a core diameter of 1.8 mm to 5 mm is a plane perpendicular to the central axis of the POF. The angle is 10 degrees or more and 40 degrees or less from the oblique end face and is perpendicular to the perpendicular line from the most acute angle portion between the oblique end face and the outline of the POF parallel to the central axis of the POF to the central axis of the POF. And the optical axis of the light receiving element and the light collecting condensing means on the side of the sharpest angle portion and the light emitting element and the light collecting condensing means on the side opposite to the sharpest angle portion with respect to a plane including the central axis of the POF. An optical axis is arranged, and at least a part of the light from the light emitting element is incident on the POF, and the light emitted from the POF is detected by the light receiving element via the light receiving condensing means, and the output is AD converted. Signal processing with threshold processing via Optical transmission and reception system using a single POF, characterized in that input to the location is output from the signal processing unit after the signal processing.     One POF has a POF portion having a diameter of 1.5 mm or less in the core portion coupled by the diameter changing means, and stores the received light amount signal immediately after power-on or during a predetermined operation, 10. The optical transmission / reception according to claim 8, further comprising a signal processing device that performs signal processing including threshold processing after subtracting the stored light reception amount signal from the light reception amount signal. system     The optical transmission / reception system according to claim 9, further comprising one or a plurality of detachable optical connection portions in the middle of one POF.