JP2006184271A - Method and apparatus for measuring eccentricity of core, and method for manufacturing optical connector plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relatively easily measure the core eccentricity of a ferrule. <P>SOLUTION: The method for measuring the core eccentricity of the ferrule with a plurality of keyways comprises a step of measuring an insertion loss for each of a plurality of keyways, by connecting a ferrule to be measured opposed to an eccentric master ferrule of which core eccentricity in the core center of an optical fiber is known, and in which an eccentric direction thereof is combined in an eccentricity reference direction where the projection of an optical connection is positioned, and then rotating either the eccentric master ferrule or the ferrule to be measured about an axis; a step of calculating the core eccentricity of a position shift from the core center of the ferrule to be measured to a reference position assuming that a center position to the periphery of the ferrule to be measured is the reference position, based on the shift length, and a length shifted from the core center of the eccentric master ferrule from an insertion loss value; and a step of calculating the eccentric angle of a core between a direction from the reference position to the core center of the ferrule to be measured and the eccentricity reference direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a core eccentricity measuring device and measuring method for a ferrule, which is a plug-side component constituting an optical connector, and a method for manufacturing an optical connector plug.

  2. Description of the Related Art Conventionally, for example, a detachable optical connector is used for connection of an optical fiber cable or an optical fiber cord used for wiring in a building or equipment, that is, optical connection between optical fibers.

  Such an optical connector is generally composed of an optical connector plug to which a ferrule that inserts and holds the tip of an optical fiber is fixed, and an optical connector adapter that is fitted from both opposite sides of the optical connector plug. .

  6 is an exploded perspective view of a general optical connector plug, FIG. 7 is a schematic view of a plug ferrule, (a) is a perspective view, (b) is a cross-sectional view, (c ) Is a plan view of the end face side of the optical fiber.

  As shown in the figure, the optical connector plug 1 holds a plug housing 2 fitted into an SC type optical connector adapter, a plug frame 3 fitted into the plug housing 2, and an optical fiber 7 for optical connection. A flanged ferrule 4 inserted from the rear of the plug frame 3, a stop ring 5 whose front end engages with a rear end of the plug frame 3, and a flange held between the flanged ferrule 4 and the stop ring 5. And an urging spring 6 for urging the ferrule 4 toward the tip end in the axial direction. In this embodiment, the ferrule 4 with a flange includes a ferrule cylinder 4a that holds the optical fiber 7, and a flange cylinder 4b that is fixed to one end of the ferrule cylinder 4a.

  The ferrule cylindrical body 4a has a substantially cylindrical shape, and an optical fiber insertion hole 4c that penetrates in the axial direction and holds the optical fiber 7 is provided therein. A tapered portion 4d having an inner diameter that gradually increases toward the opening is provided at the rear end of the optical fiber insertion hole 4c. By providing such a tapered portion 4d, when the optical fiber 7 is inserted into the optical fiber insertion hole 4c, the tip of the optical fiber 7 comes into contact with the end face of the ferrule cylindrical body 4a, and is chipped or broken. Can be prevented.

  Examples of the material of the ferrule cylindrical body 4a include ceramic materials such as zirconia, plastic materials, and glass materials such as crystallized glass, borosilicate glass, and quartz.

  Here, the optical fiber 7 described above is a single mode (SM), and includes a core 7a of the optical fiber 7 and a clad 7b covering the core 7a as shown in FIG. 7C. Such an opposing connection between the optical fibers 7 is performed by bringing the cores 7a into contact with each other.

  On the other hand, the flange cylinder 4b has a flange recess 4e for fitting one end of the ferrule cylinder 4a and an optical fiber core insertion hole 4f for inserting and holding the optical fiber core 7c coated on the outer periphery of the optical fiber 7. And a flange 4g provided on the outer periphery of the opening side of the flange recess 4e so as to project a predetermined amount in the radial direction over the circumferential direction.

  The flange 4g is provided with four key grooves 4h that can determine the eccentric reference direction of the core of the optical fiber 7 at 90 ° intervals in the circumferential direction. Here, the eccentric reference direction of the core of the optical fiber 7 is a direction indicating the position of the key groove 4h closest to the core 7a of the optical fiber 7 in this embodiment.

  The number, position, depth, shape, and the like of the key grooves 4h are not particularly limited, and may be determined as appropriate according to the plug frame 3 that positions the ferrule 4 with a flange. Moreover, as a material of the flange cylinder 4b, metal materials, such as stainless steel, brass, iron, can be mentioned, for example, In this embodiment, stainless steel was used.

  Here, the assembly process of the ferrule 4 with a flange mentioned above is demonstrated. First, the ferrule cylinder 4a is press-fitted into the flange recess 4e of the flange cylinder 4b. Next, after passing the stop ring 5, the urging spring 6 and the like through the optical fiber core 7c, the optical fiber 7 from which the coating at the tip of the optical fiber core 7c has been removed is placed in the optical fiber insertion hole 4c with an adhesive ( (Not shown). At this time, the optical fiber core wire 7c is also fixed in the optical fiber core wire insertion hole 4f with an adhesive. Thereafter, the end face of the ferrule cylindrical body 4 a is polished together with the end face of the optical fiber 7. Thereby, the ferrule 4 with a flange mentioned above is completed. After that, the flanged ferrule 4 selected by the flanged ferrule 4 selection method, which will be described later, is fixed to the plug frame 3 and the plug housing 2 to form the optical connector plug 1.

  Recently, when the optical fibers of the optical connector plug described above are connected to each other via an optical connector adapter, optical connection with a relatively low insertion loss is desired.

  Here, the loss factors at the time of optical connection between the optical fibers include, for example, the angle deviation between the optical fibers, the core eccentricity, the gap, the optical fiber end face quality, the end face reflection, and the like. It is generally known that the amount of eccentricity between the cores causes the largest insertion loss.

  For example, in the case of the optical connector plug 1 having the single-mode optical fiber 7, the core eccentricity between the optical fibers is determined by the position of the center of the cross section relative to the outer diameter of the ferrule 4 a serving as a reference at the time of optical connection This is a value generated by a positional shift from the core center.

  For this reason, conventionally, in order to guarantee the low-loss optical connector plug 1, for example, the core eccentricity of each optical connector plug 1 is measured using a measuring device such as a core eccentricity measuring device or a core eccentricity measuring system, The amount of core eccentricity is provided to the user as a standard value.

  In such a core eccentricity measuring device, first, light is passed through the ferrule 4a in a state where the ferrule 4a is fixed between the V groove and the pressing member, and the core center of the optical fiber 7 is enlarged by the lens. And import it into the image processing apparatus. Next, the ferrule 4a is removed from the V-groove, rotated by a predetermined angle and fixed to the V-groove again, and the core center of the optical fiber is again magnified by the lens and taken into the image processing apparatus. Normally, the core center of the optical fiber 7 is estimated by performing such an operation four times and performing image processing on the core center of the optical fiber 7 for each rotation using an image processing device. From this, the amount of core eccentricity is measured (see Non-Patent Document 1).

In the second conventional example, the measured ferrule is oppositely connected to the eccentric master ferrule whose core center of the optical fiber 7 is at a predetermined reference position, and the measured ferrule is rotated around its axis to reduce the insertion loss. The position of the reference direction where the insertion loss value becomes the minimum value is determined as the eccentric reference direction, and the coordinates of the estimated position of the core 7a for each rotational position with the reference position as the coordinate center are defined as the estimated position and the coordinate center. And the rotation center of the ferrule to be measured is calculated from the coordinates of the estimated position for each rotation position, and the estimated position of the core 7a of the non-measurement ferrule with respect to the rotation center is calculated as the core center. Calculated as information, the axis deviation angle with respect to the eccentric reference direction of the core 7a of the measured ferrule calculated from the eccentric reference direction and the core center information, and the core deviation from the rotation center. By sorting on the basis of the amount, sorting method and a manufacturing method of the optical connector adapter ferrule can be screened flanged ferrule 4 of low loss relatively easily has been proposed (see Patent Document 1).
NTT-AT, “core eccentricity measurement system CENTROC”, [online], [searched on August 27, 2002], Internet <URL: http: // www. keytech. ntt-at. co. jp / optic1 / prd_0028. html> JP 2004-117656 A

  However, in the conventional method for measuring the amount of core eccentricity in the first example, since the ferrule 4a is fixed and measured between the V-groove and the holding member for each rotation, the workability is very poor. For example, dust or the like adheres to the end face, and it takes much time and effort to obtain a stable core eccentricity.

  That is, conventionally, in order to measure a stable core eccentricity, the core eccentricity is measured only when the core center for each rotation of the ferrule 4a enters a predetermined estimation range. However, as described above, the core center for each rotation often does not fall within the predetermined estimation range because of poor workability when measuring the amount of core eccentricity. In such a case, measurement must be repeatedly performed until the core center falls within the estimated range, and it takes much time to measure a stable core eccentricity.

  Therefore, there is a problem that the working efficiency for measuring the core eccentricity is low and the manufacturing cost is high. For this reason, even if it can cope with cost to sort out the expensive ferrule 4 with flange for master, it is not profitable in cost to sort out cheap standard ferrule 4 with flange. There's a problem.

  As described above, since it takes time to measure a stable core eccentricity, there is a problem that it is relatively difficult to estimate the core center of the optical fiber 7.

  Further, in the conventional method for measuring the amount of core eccentricity in the second example, there are many amounts to be calculated such as the reference position, the eccentricity reference direction, and the rotational position. Therefore, a calculation error from the measurement error occurs, and the correct eccentricity reference is generated. The core eccentric angle with respect to the direction and the amount of core eccentricity from the reference position cannot be obtained, resulting in a problem that it is not adopted.

  In view of such circumstances, an object of the present invention is to provide a core eccentricity measuring apparatus and measuring method for a ferrule 4 with a flange, and a method for manufacturing an optical connector plug, which can relatively easily measure the core eccentricity of the ferrule 4 with a flange. .

  The present invention has been made in view of the above problems, and in the core eccentricity measuring method for a ferrule having a flange having a plurality of keyways, the core eccentricity at the core center of the optical fiber is known, and the optical Connect the measured ferrule opposite to the eccentric master ferrule whose eccentric direction is aligned with the eccentric reference direction where the protrusion of the connector plug is located, and rotate one of the eccentric master ferrule or measured ferrule around its axis to A step of measuring an insertion loss for each of the plurality of key grooves, a step of calculating a deviation amount from the core center of the eccentric master ferrule from the insertion loss value, and a center position with respect to the outer periphery of the ferrule to be measured based on the deviation amount As a reference position, a core eccentricity amount that is a deviation of the position of the measured ferrule from the core center with respect to the reference position, and the reference position It characterized by having a step of calculating the direction and forms the core eccentricity angle of the eccentric reference direction to the core center of the measured ferrule from.

  The core eccentric amount and the core eccentric angle are displayed on a display.

  The key groove position having the smallest core eccentric angle is selected.

  A core eccentricity measuring apparatus for measuring an eccentricity of a core center of an optical fiber with respect to an outer periphery of a ferrule having a flange formed with a plurality of key grooves, wherein an optical adapter having a position fixing protrusion that can be engaged with the key groove of the ferrule. A mounted ferrule holder, a light source for the optical fiber, a photodetector for detecting light from the light source, a data processor for calculating a result of detecting the light, a display for displaying a calculation result, An eccentric master cord having an eccentric master ferrule whose eccentricity at the center of the core of the optical fiber is known at one end is characterized.

  The data processor and the display are integrated.

  The ferrule is assembled using a ferrule measured by the core eccentricity measuring device or the core eccentricity measuring method.

  In view of the above, the present invention relates to a method for measuring the core eccentricity of a ferrule provided with an optical fiber, by passing the measured ferrule and the amount of core eccentricity at the core center of the optical fiber and the eccentric master ferrule whose eccentric direction is known through a split sleeve. Measuring a plurality of insertion loss values L by rotating one of the eccentric master ferrule and the measured ferrule around the axis, and measuring the ferrule to the core center of the eccentric master ferrule from the insertion loss value L A core center deviation amount d, a center position of the measured ferrule with respect to the outer periphery as a reference position O, a core eccentricity δ that is a position deviation from the core center of the measured ferrule, and the reference position The amount of deviation d is defined as the core eccentric angle θ formed by the direction from O to the core center of the ferrule to be measured and the eccentric direction of the eccentric master ferrule. And calculating based on the above.

  Further, the core eccentric amount and the core eccentric angle are displayed on a display.

  Further, the key groove position having the smallest core eccentric angle is selected.

  Also, a position fixing protrusion that can be engaged with the key groove of a ferrule having a flange formed with a plurality of key grooves, a ferrule holder that mounts an optical adapter having a split sleeve, a light source for the optical fiber, and the light source A light detector for detecting light from the light source, a data processor for calculating the result of detecting the light, a display for displaying the result of the calculation, and an eccentric master having a known eccentric amount at the core center of the optical fiber at one end An eccentric master code having a ferrule is provided, and the amount of eccentricity at the core center of the optical fiber can be measured.

Further, the position fixing protrusion is made of a material having a higher thermal expansion coefficient than the flange, and the position fixing protrusion in a state of being inserted into the key groove is thermally expanded so that the position fixing protrusion is pressed against the inner surface of the key groove. Thus, the both side surfaces of the fixed projection are engaged with the inner surfaces of the opposing key grooves.
Further, the width of one end of the position fixing projection is made smaller than the opening width of the key groove having a constant width and larger than the opening width of the key groove toward the other end. .
Further, the position fixing protrusion in an elastically deformed state is brought into pressure contact with the inner surface of the key groove, whereby both side surfaces of the position fixing protrusion are engaged with the inner surface of the opposing key groove.
Further, the data processor and the display are integrated.

  Further, it is assembled using a ferrule measured by the above-mentioned core eccentricity measuring method.

  Further, the key groove position having the smallest core eccentric angle is aligned with the direction of the protrusion of the plug housing.

  As described above, according to the present invention, in the method for measuring the core eccentricity of a ferrule having a flange having a plurality of keyways, the amount of core eccentricity at the core center of the optical fiber is known, and the position of the protrusion of the optical connector plug The measured ferrule is oppositely connected to an eccentric master ferrule whose eccentric direction is aligned with the eccentric reference direction, and either one of the eccentric master ferrule or the measured ferrule is rotated about its axis, and each of the plurality of key grooves is A step of measuring an insertion loss, a step of calculating a deviation amount from the core center of the eccentric master ferrule from the insertion loss value, and a center position with respect to the outer periphery of the ferrule to be measured based on the deviation amount as a reference position. The core eccentricity, which is the position deviation of the measured ferrule from the core center with respect to the position, and the measured ferrule from the reference position By comprising the step of calculating the direction and forms the core eccentricity angle of the eccentric reference direction to the core center, it is possible to perform core eccentricity measurement of the ferrule relative ease.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the core eccentricity measuring device 9 of the present invention includes a ferrule 4a that holds an optical fiber, and a ferrule 4a that is fixed to the ferrule 4a and includes a flange 4g that has a plurality of key grooves 4h. In the core eccentricity measuring device of the measured ferrule 8a for measuring the core eccentricity δ of the core center with respect to the outer peripheral center position, a light source 9a equipped with a laser, a photodetector 9d equipped with a light receiving sensor, and a data processing A data processor 9e, a display 9f for displaying measurement results, a ferrule holder 9b having an optical adapter 9h and a position fixing projection 9c for engaging the keyway of the ferrule, and an eccentric master ferrule 8b are provided at one end. The eccentric master code 8c.

  Here, the core eccentricity measuring device 9 is a so-called notebook personal computer in which the data processor 9e and the display 9f are integrated.

  As a measuring method, there are procedures for measuring the insertion loss L1 to Ln for each key groove, measuring the deviations d1 to dn from the insertion loss, and then calculating the core eccentricity and the core eccentric angle.

  2 to 4, the core eccentricity measuring method of the present invention includes a ferrule 4a that holds an optical fiber 7, and a flange 4g that is fixed to the ferrule 4a and has a plurality of key grooves 4h. In the core eccentricity measuring method of the measured ferrule 8a, the core eccentricity δ at the core center of the optical fiber 7 is known and the eccentricity is aligned with the eccentric reference direction 10 where the protrusion of the optical connector plug 1 is located. A process of measuring the insertion loss for each of the plurality of key grooves 4h by causing the measured ferrule 8a to face the master ferrule 8b and rotating one of the eccentric master ferrule 8b or the measured ferrule 8a about its axis. Calculating a deviation amount of the eccentric master ferrule 8b from the core center from the insertion loss value, and measuring the measured ferrule based on the deviation amount. The center position with respect to the outer periphery of the tool 8a is defined as a reference position O, the core eccentricity δ, which is a shift of the position of the measured ferrule 8a from the core center with respect to the reference position O, and the core of the measured ferrule 8a from the reference position O And a step of calculating a core eccentric angle θ formed by the direction toward the center and the eccentric reference direction 10.

  First, an eccentric master ferrule 8b in which the core center of the optical fiber 7 is in the eccentric reference direction 10 is prepared.

  For example, in this embodiment, an eccentric master ferrule 8b having a core eccentricity δ of 0.99 μm is prepared using a core eccentricity measuring device (NTT-AFTY “PSI-101 type”). As shown in FIG. 3A, the core center of the eccentric master ferrule 8b coincides with the position A of the key groove 4h of the flange 4g, that is, is aligned with the closest position A of the key groove 4h. The direction of the position A of the keyway 4h is defined as the eccentric reference direction 10.

  Next, the measured ferrule 8a connected to the light source 9a is fixed by the position fixing protrusion 9c at a predetermined position where the position A of the key groove 4h is in a predetermined direction, and in FIG. Then, as shown in FIG. 2B, the eccentric master ferrule 8b is inserted into the opening on one side of the split sleeve 9g, and then connected to the photodetector 9d at the opening on the other side of the optical connection sleeve 9g. By inserting the eccentric master ferrule 8b, the end faces of the optical fibers are connected to each other.

  Next, the insertion loss when the two are connected to each other via the split sleeve 9g, that is, the magnitude of light (light intensity) at the time of optical connection is measured by the photodetector 9d, and then the ferrule 8a to be measured is predetermined. Rotate each angle and measure each insertion loss.

  For example, in the present embodiment, as shown in FIG. 2 (c), the key grooves 4h are provided at four positions at 90 ° intervals along the circumferential direction of the flange 4g. The ferrule 8a is rotated 90 ° counterclockwise, and the key groove 4h is engaged with the position fixing projection 9c each time, and the rotation is precisely 90 °, so that the optical detector 9d corresponds to the core center for each rotation. The inserted insertion loss values L1, L2, L3, and L4 are read.

Here, a deviation of the rotation angle due to the clearance between the furan 4g and the keyway 4h causes a measurement error, but it can be improved by the following embodiment.
For example, in FIG. 2, the position fixing protrusion 9c is made of a material having a higher thermal expansion coefficient than the flange, and after the position fixing protrusion 9c is inserted into the key groove 4h, the position fixing protrusion 9c is heated to expand. Thus, the core eccentricity measurement can be performed with the key groove 4h being engageable.
Stainless steel is usually used for the flange 4g, and there is no problem if the position fixing projection 9c has a thermal expansion coefficient equal to or higher than that of stainless steel. Even if the clearance between the width of the position fixing protrusion 9c and the opening width of the key groove 4h is slightly increased, if the lower pedestal integrated with the position fixing protrusion 9c expands greatly, tensile stress acts on the position fixing protrusion 9c. Furthermore, the key groove 4h can be engaged with no gap.
As the heating means, a ceramic heater (not shown) or the like capable of rapid heating is preferably incorporated in the lower pedestal integrated with the position fixing protrusion 9c.
Further, the cooling means needs to be rapidly cooled in order to smoothly remove the flange 4g, but it is sufficient if the lower pedestal integrated with the position fixing projection 9c heat sinks to other members.
As another embodiment, as shown in FIG. 3, the width of one end of the position fixing projection 9c is made smaller than the opening width of the key groove 4h, and the width toward the other end is made larger than the opening width of the key groove 4h. By making it large, the core eccentricity can be measured so that there is no deviation of the rotation angle.
3A shows the relationship between the position fixing protrusion 9c and the key groove 4h in the cross section in FIG. 3C, but the key groove 4h is inserted from the position fixing protrusion 9c having a width smaller than the opening width of the key groove 4h. To do.
FIG. 3B shows the relationship between the position fixing projection 9c and the key groove 4h in the cross section in FIG. 3D, but the position is the portion where the opening width of the key groove 4h is equal to the width of the position fixing projection 9c. By engaging the key groove 4h with the fixed protrusion 9c, the core eccentricity can be measured so that there is no deviation of the rotation angle.
As yet another embodiment, the position fixing projection 9c is elastically deformed so as to be smaller than the opening width of the key groove 4h as shown in FIG. By engaging the position fixing projection 9c with the key groove 4h, the core eccentricity can be measured so that there is no deviation of the rotation angle by engaging the position fixing projection 9c and the key groove 4h.
Thereafter, from the respective insertion loss values L1 to L4 read from the photodetector 9d, the following equation (1) showing the relationship between the generally known deviation amount d and the insertion loss value L is modified ( D1 to d4 are calculated from 2). Expression (1): L = L0 × (d / ω) 2 where L: insertion loss (dB), L0: coefficient when only the deviation amount is considered, d: deviation amount (μm), ω: mode field Radius (μm), formula (2): d = (L × ω 2 /4.34) 1/2. In the present invention, the calculation was performed with L0 = 4.34 and ω = 4.7 μm.

  Next, as shown in FIG. 4, the core which is the positional deviation between the values of the deviations d1 to d4 and the known eccentricity d0 of the eccentric master ferrule and the core center of the ferrule 8a to be measured with respect to the reference position O. The eccentricity δ and the core eccentric angle θ formed by the direction from the reference position O to the core center of the ferrule 8a to be measured and the eccentric reference direction 10 are calculated.

  Hereinafter, the calculation of the core eccentricity δ and the core eccentric angle θ will be described in detail with reference to FIG.

  A center position with respect to the outer periphery of the ferrule 4a is set as a reference position O, the reference position O is set as a reference coordinate axis, an X-axis direction is set as an eccentric reference direction 10, and a core center of the eccentric master ferrule 8b is set as R. Since the eccentric amount d0 of R is known and the eccentric direction is aligned with the eccentric reference direction 10, the coordinates thereof are R (d0, 0).

  Next, the deviations d1, d2, d3, and d4 calculated from the above equation (2) are values that have been rotated 90 ° to the left with respect to the reference position O. Therefore, the coordinates are P1 (δCOSθ , ΔSINθ), P2 (−δSINθ, δCOSθ), P3 (−δCOSθ, δSINθ), and P4 (δSINθ, δCOSθ).

  Here, from the relation of the trigonometric function, the equation (3): d1 = {(d0−δCOSθ) 2+ (δSINθ) 2} 1/2 is calculated by repeating this operation from d2 to d4. From the formula, formula (4): δ13 = {(d12 + d32-2d02)) / 2} 1/2 is derived.

  Further, from the equations d2 and d4, the equation (5) δ24 = {(d22 + d42-2d02) / 2} 1/2 is derived.

  Let δ be the average value of δ13 and δ24.

  As described above, the core eccentricity δ is obtained. Therefore, when δ is substituted into Equation (6) θ = COS−1 {(d02 + δ2−d12)) / (2d0δ)} obtained by modifying Equation (3), θ is obtained. The core eccentricity δ and the core eccentric angle θ are obtained from the original.

  Here, when x is an allowable variation core eccentricity, if | δ−δ13 |> x or | δ−δ24 |> x, it is desirable to remeasure the connection loss values L1 to L4. This is because the connection loss is largely caused by fluctuations in the measured value due to dust on the ferrule tip. At the time of re-measurement, it is desirable to clean the tip surfaces of both the measured ferrule 8a and the eccentric master ferrule 8b.

  When the single mode optical fiber is connected, the allowable variation core eccentricity x is preferably in the range of 0.1 to 0.5 μm, and if it is less than 0.1 μm, the measurement accuracy is sufficient, and it is necessary to remeasure. If the thickness exceeds 0.5 μm, the error is too large and the reliability of the obtained core eccentricity is lost. Within this range, it is preferably 0.2 to 0.3 μm.

  In addition, when connecting a multimode optical fiber, the range of 0.5 to 3 μm is desirable, and if it is less than 0.5 μm, there is no need to remeasure because the measurement accuracy is sufficient, and if it exceeds 3 μm, This is because the error is too large and the credibility of the obtained core eccentricity is lost. Within this range, it is preferably 1 to 2 μm.

  In the above description, the shift amount d indicates the distance between the core center of the eccentric master ferrule 8b and each of the coordinate points P1, P2, P3, P4, and is a value in the middle of calculation calculated by the above equation (2). Therefore, it is different from the core eccentricity δ, which is the deviation of the center position of the core of the ferrule 8a to be measured from the reference position O that is the true center position of the outer periphery of the ferrule 4a.

  It is a feature of the present invention that the above calculation is performed by a data processor and the calculation result is displayed on the display. However, the effect of the present invention can also be obtained by performing manual calculation using a calculator or the like without using the data processor and the display. Unchanged.

  Note that a low-loss connection loss can be obtained by selecting a key groove position having the smallest core eccentric angle θ.

  Here, the measured ferrule 8a measured by the method described above is based on a mark (not shown) of the key groove 4h indicating the eccentric direction of the core center of the optical fiber 7, as shown in FIG. Then, the plug frame 3 is fitted.

Next, the plug housing 2 having the protrusion 2 a is fitted on the outer periphery of the plug frame 3.

  Thereby, the optical connector plug 1 as shown in FIG. 5B is completed, and the direction of the protrusion 2a of the plug housing 2 and the eccentric reference direction 10 can be aligned.

  Thus, in the present invention, the optical connector plug 1 is manufactured by positioning and fixing the flanged ferrule 4 to the plug frame 3 based on the key groove 4h corresponding to the eccentric reference direction 10 of the core eccentricity. When the connector plug 1 is used for facing connection, the core centers of the optical fibers 7 are substantially coincident, and optical connection with low loss can be performed.

  Further, as described above, since the measured ferrule 8a can be measured and mass-produced on the basis of the eccentric master ferrule 8b in which the core of the optical fiber 7 is decentered by a predetermined amount, the optical connector can be manufactured using the ferrule 4 with a flange. By manufacturing the plug 1, it is possible to realize the optical connector plug 1 that can always perform optical connection with stable insertion loss.

  Further, as described above, since the eccentric master ferrule 8b and the measured ferrule 8a are optically connected via the split sleeve 9g, the core eccentricity measuring device or the like is provided between the V groove and the presser member for each rotation. Since the work of fixing the ferrule 8a to be measured can be omitted, workability can be improved and dust or the like does not adhere to the end face of the ferrule 8a to be measured. Accordingly, a relatively stable insertion loss value can be measured. Therefore, the working efficiency of measuring the core eccentricity δ and the core eccentric angle θ can be improved, and the manufacturing cost can be reduced.

  Furthermore, since the optical connector plug 1 can be used not only for manufacturing the optical connector plug 1 for the master but also for manufacturing the optical connector plug 1 for the standard, it is possible to realize the optical connector plug 1 with the same low loss as the master.

  Although the embodiments of the present invention have been described above, the basic configuration of the ferrule measurement method and the optical connector plug manufacturing method is not limited to the above-described ones.

  For example, in the above-described configuration, the SC type optical connector plug 1 is exemplified, but the optical connector plug 1 having the single mode (SM) optical fiber 7 is not limited, and for example, MU type, LC type, FC It may be an optical connector plug 1 of a type or ST type.

  Moreover, in embodiment mentioned above, although insertion loss value L1-L4 when rotating the ferrule 4 with a flange every 90 degrees was measured, it is not limited to this, The ferrule 4 with a flange is at least 2 times, ie, 180. You may make it measure the insertion loss value at the time of rotating for every degree.

  Thus, in the measuring method of this invention, since it can carry out according to the conventional eccentric direction alignment process, the ferrule 4a can be measured without increasing the number of processes.

  In addition, the process of measuring the master ferrule using a core eccentricity measuring device or the like can be replaced with the measurement method of the present invention, and the number of processes for measuring the master ferrule can be reduced. In addition to measuring the master ferrule, the core eccentricity δ can be calculated more stably as compared with a conventional core eccentricity measuring device or the like, and therefore can be applied to measurement of a standard ferrule. Therefore, it is possible to select the flanged ferrule 4 with a low insertion loss of 0.1 dB or less, which is equal to or less than that of the master, regardless of the use of the ferrule such as the master or the standard.

  As an example of the present invention, the core eccentricity δ of the ferrule to be measured was measured by the method of the present invention.

  The core eccentricity δ of the known eccentric master ferrule 8b is 0.91 μm, and the eccentric master ferrule 8b is aligned with the eccentric reference direction 10 to measure connection loss in four directions.

  The connection loss value was calculated using equations (1) to (6) to determine the core eccentricity δ and the core eccentric angle θ, and the above measurement was repeated three times for the same sample.

  As a comparative example, the core eccentricity δ was measured by rotating the ferrule 4a on the V groove. The used sample was measured repeatedly three times using the same sample of the example of the present invention.

The results are shown in Table 1.

  As described above, in the comparative example, only the amount of core eccentricity can be measured, and the results of the three measurements produced a variation of 0.33, 0.23, and 0.31 μm, which is 0.13 μm at the maximum. On the other hand, in the present invention, there was only a variation of 0.018 μm at the maximum of 0.288, 0.292, and 0.274 μm, resulting in stable repeat measurement accuracy.

  Further, the core eccentric angle could not be measured in the comparative example, but the value could be easily obtained in the present invention.

It is a fragmentary sectional view which shows the core eccentricity measuring apparatus of this invention.

(A)-(c) is the figure which showed the procedure of the core eccentricity measuring method of this invention. (A) is a cross-sectional view showing the relationship between the position fixing protrusion and the key groove in the cross section in (c), (b) is a cross-sectional view showing the relationship between the position fixing protrusion and the key groove in the cross section in (d), (c) Is a position where the key groove is inserted into the position fixing protrusion, (d) is a position where the key groove is engaged with the position fixing protrusion, (e) is a state before the key groove is engaged with the position fixing protrusion, ( f) shows a state after the key groove is engaged with the position fixing protrusion. It is a schematic diagram explaining the relationship between the amount of shaft eccentricity and a shaft offset angle of the present invention. (A) And (b) is the exploded view and assembly sectional drawing of the optical connector plug of this invention, respectively. It is a perspective exploded view of a general optical connector plug. (A), (b) is the perspective view and partial sectional view of a general plug ferrule, respectively, (c) is a top view of an optical fiber.

Explanation of symbols

1: optical connector plug 2: plug housing 2a: protrusion 3: plug frame 4: flanged ferrule 4a: ferrule 4b: flange cylinder 4c: optical fiber insertion hole 4d: taper portion 4e: flange recess 4f: optical fiber core wire insertion Hole 4g: Flange 4h: Key groove 5: Stop ring 6: Biasing spring 7: Optical fiber 7a: Core 7b: Clad 7c: Optical fiber core wire 8a: Measuring ferrule 8b: Eccentric master ferrule 8c: Eccentric master cord 8d: Measurement code 9: Core eccentricity measuring device 9a: Light source 9b: Ferrule holder 9c: Position fixing projection 9d: Photo detector
9e: Data processor 9f: Display 9g: Split sleeve 9h: Optical adapter 10: Eccentric reference direction O: Reference position R: Eccentric master ferrule core center

Claims (10)

In the method of measuring the core eccentricity of a ferrule provided with an optical fiber, a ferrule to be measured and an eccentric master ferrule whose core eccentricity at the core center of the optical fiber and the eccentric direction are known are connected to each other through a split sleeve, and the eccentric master Rotating one of the ferrule or the measured ferrule about the axis to measure a plurality of insertion loss values L, and a deviation d of the core center of the measured ferrule from the core center of the eccentric master ferrule from the insertion loss value L A center position with respect to the outer periphery of the measured ferrule is a reference position O, a core eccentricity δ that is a position deviation from the core center of the measured ferrule, and a core of the measured ferrule from the reference position O A process for calculating the core eccentric angle θ formed by the direction toward the center and the eccentric direction of the eccentric master ferrule based on the deviation d. A core eccentricity measuring method characterized by comprising: The core eccentricity measuring method according to claim 1, wherein the core eccentricity amount and the core eccentric angle are displayed on a display. 3. The ferrule core eccentricity measuring method according to claim 1, wherein a key groove position having the smallest core eccentric angle is selected. A position fixing protrusion capable of engaging with the key groove of a ferrule having a flange formed with a plurality of key grooves, a ferrule holder equipped with an optical adapter having a split sleeve, a light source for the optical fiber, and the light source , A data processor for calculating the result of detecting the light, a display for displaying the calculation result, and an eccentric master ferrule whose eccentric amount at the core center of the optical fiber is known at one end A core eccentricity measuring apparatus, characterized in that it can measure the amount of eccentricity at the core center of an optical fiber. The position fixing protrusion is made of a material having a higher thermal expansion coefficient than the flange, and the position fixing protrusion in a state of being inserted into the key groove is thermally expanded, so that the position fixing protrusion is pressed against the inner surface of the key groove. 5. The core eccentricity measuring apparatus according to claim 4, wherein both side surfaces of the fixed projection are engaged with the inner surface of the key groove facing each other. The width of one end of the position fixing projection is made smaller than the opening width of the key groove having a constant width and larger than the opening width of the key groove toward the other end. Item 5. The core eccentricity measuring device according to Item 4. 5. The position fixing protrusion in an elastically deformed state is brought into pressure contact with the inner surface of the key groove, whereby both side surfaces of the position fixing protrusion are engaged with the inner surface of the opposing key groove. Core eccentricity measuring device. 8. The core eccentricity measuring apparatus according to claim 4, wherein the data processor and the display are integrated. A method for manufacturing an optical connector plug, wherein the optical connector plug is assembled by using a ferrule measured by the core eccentricity measuring method according to claim 1. 10. The method of manufacturing an optical connector plug according to claim 9, wherein the key groove position having the smallest core eccentric angle is aligned with the direction of the protrusion of the plug housing.

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