JPH11142687A - Ferrule and optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrule and optical connector which can easily be assembled while given high reliability by suppressing the extreme bending or buckling of an internal fiber at the time of assembly. SOLUTION: The ferrule has a ferrule substrate 21 which has a front half part 21b and a rear half part 21c so that a fixation hole 21d for the internal fiber 22 is formed in the front half part 21b and the rear half part 21c has its upper half made open, a fiber groove 21e for positioning an optical fiber FOP on the top surface of the rear half part coaxially with the axis of the fixation hole 21d, and has the internal fiber 22 fixed from the tip of the fixation hole 21d to part of the fiber groove 21e, a lid member which is made to cover the rear half part of the ferrule substrate 21, and a hold member which elastically holds the ferrule substrate and lid member. In this case, a hollow part 21g is formed from the rear end part 21j of the fixation hole 21d to the end part 21k of the fiber groove 21e and the length L of the hollow part 21g is 2.5 to 8 (mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferrule and an optical connector used for mechanically connecting optical fibers.

[0002]

2. Description of the Related Art To manufacture an optical connector used for mechanically connecting an optical fiber, an optical fiber core wire is bonded and fixed to a ferrule, and the connection end surface of the ferrule where the tip of the optical fiber is exposed is mirror-polished by a polishing machine. Is required.

[0003] For this reason, a polishing machine,
A special machine such as a heating machine for curing the adhesive is required.

[0004]

In recent years, with the widespread development of optical communication networks in general homes and the like, it has been required to assemble and process optical connectors at sites where optical fibers are laid. .

However, assembling an optical connector requires a high level of technical skill, and requires a plurality of tools and a large amount of time (about one hour per terminal of an optical fiber).

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a ferrule and an optical connector which enable anyone to easily connect an optical fiber with a simple tool without a processing facility. Aim.

In particular, it is an object of the present invention to prevent the built-in fiber from being extremely bent or buckled during assembly, and to provide the ferrule and the optical connector with high reliability.

[0008]

According to the present invention, there is provided a ferrule having a first half portion and a second half portion, wherein a fixing hole for an optical fiber is formed in the front half portion, and The upper half of the section is open, and the upper half of the section is coaxial with the axis of the fixing hole, and at least one of the optical fibers is
A positioning groove for positioning more than one is formed, and a ferrule substrate to which a built-in fiber whose rear half portion has been mirror-cut in advance over a part of the positioning groove from the tip of the fixing hole is fixed, and a rear half portion of the ferrule substrate. A ferrule having a cover member that is attached and provided with a notch that forms a recess between the ferrule substrate and the outer edge of the ferrule substrate when attached, and a holding member that elastically holds the ferrule substrate and the cover member. A hollow portion is formed between the rear end of the fixing hole and the end of the positioning groove, and the length L of the hollow portion is set in a range of 2.5 (mm) ≦ L ≦ 8 (mm). This is the configuration that has been implemented.

According to another aspect of the present invention, there is provided an optical connector having a front half and a rear half, wherein the front half has an optical fiber fixing hole, and the rear half has an upper part. A half is opened, and a positioning groove for positioning at least one or more optical fibers is formed on the upper surface of the rear half portion coaxially with an axis of the fixing hole, and a positioning groove is formed in advance from a tip of the fixing hole to a part of the positioning groove. A ferrule substrate to which a built-in fiber whose rear half is mirror-cut is fixed, and a lid member which is attached to the rear half of the ferrule substrate and has a cutout which forms a concave portion between the ferrule substrate and an outer edge of the ferrule substrate when the ferrule substrate is attached. And a holding member for elastically holding the ferrule substrate and the lid member, wherein a hollow portion is formed from a rear end of the fixing hole to an end of the positioning groove, and Length L is A predetermined clearance is provided between the ferrule set in the range of 5 (mm) ≦ L ≦ 8 (mm) and the ferrule, a stop ring inserted through a spring, and a stop ring attached to the stop ring. It is configured to have a plug frame for wearing and holding the ferrule.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of a ferrule and an optical connector which can be easily assembled will be described below in detail with reference to FIGS.

First, the ferrule 10 is used by being incorporated into an optical connector 1 to be described later, and has a ferrule substrate 11, holding lids 13 and 14, and spring pins 15 as shown in FIG.

As shown in FIGS. 2 and 3, the ferrule substrate 11 has a cylindrical body divided into a front half part 11b and a rear half part 11c by a flange part 11a, and an optical fiber fixing hole 11d is formed at the center of the front half part 11b. Are formed. The ferrule substrate 11 is formed in a semi-cylindrical shape in which the rear half 11c is open at the upper half. The rear half portion 11c is formed such that both side edges are stepped and the cross section in the low width direction is formed in a convex shape. A coating groove 11f for positioning is formed. The shape of the fiber groove 11e and the coating groove 11f is not particularly limited as long as the optical fiber can be positioned. For example, a V groove, a U groove, or the like is preferable. Also,
As shown in FIG. 2, the covering groove 11 f has a right end widened in the width direction and a guide surface 1 for guiding insertion of an optical fiber from outside.
1 g is formed. On the other hand, the front half 11b is slightly projected from the fixing hole 11d toward the fiber groove 11e, and the built-in fiber 12 is bonded and fixed in advance.

Here, the built-in fiber 12 is
The exposed portion from d to the first half 11b, which is the butting end surface, is mirror-polished, and the second half 11c is cut into a mirror surface, and a refractive index matching agent is applied in advance.

The holding lids 13 and 14 are connected to the ferrule substrate 11.
4A and 4B, a holding lid 13 shown in FIGS. 4A and 4B is used to fit an optical fiber connected to the built-in fiber 12 into a fiber groove 11e.
4 (c) and 4 (d), the cover 14 is provided with a coating groove 11f for coating the optical fiber connected to the built-in fiber 12.
Respectively. The holding lid 13 and the holding lid 14 are
Notches 13a and 14a are formed on the sides to form a concave portion H (see FIG. 1) between the outer edge of the ferrule substrate 11 when the ferrule substrate 11 is attached. Further, the holding lid 14 has a tapered guide surface 14b on one side (the right side in FIG. 4D) on which the optical fiber is inserted.

The spring pin 15 is mounted on the ferrule substrate 1.
As shown in FIG. 5, this is a cylindrical pin that is assembled to the ferrule 10 while elastically holding the cover 1 and the holding lids 13 and 14.
A slit 15a is formed in the longitudinal direction.

The ferrule 10 configured as described above
Can be easily assembled as follows.

First, the holding lid 13 is arranged on the side of the flange 11a, and the holding lid 14 is arranged on the rear side of the holding lid 13, and fitted to the rear half 11c of the ferrule substrate 11. As a result, a recess H (see FIG. 1) is formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.

Next, the ferrule 10 shown in FIG. 1 can be assembled very easily by fitting the spring pins 15 into the ferrule substrate 11 from the rear half 11c side where the holding lids 13 and 14 are fitted. In the ferrule 10 assembled in this manner, the ferrule substrate 11 and the holding lids 13 and 14 are elastically held by the spring force of the spring pin 15. At this time, the spring pin 15
Is fitted so as not to cover the concave portion H formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.

Therefore, for example, when an optical connector is manufactured at a site where an optical fiber is laid, the ferrule 10 is easily inserted into the ferrule substrate 11 from the rear half portion 11c side and protrudes from the built-in fiber 12. Can be connected together.

That is, when the optical fiber is inserted into the ferrule 10, the wedges W corresponding to the two concave portions H formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.
A wedge W is inserted into each concave portion H using a jig having the following.
For example, as shown in FIG. 6, in the case of a concave portion H formed between the holding lid 13 and the outer edge of the ferrule substrate 11, the wedge W
Is inserted into the recess H, and the wedge W expands the recess H against the spring force of the spring pin 15.

As a result, the upper surface of the rear half 11c of the ferrule 10 is
4 and a slight gap is formed. Due to this gap,
The ferrule 10 is a second half 11 c of the ferrule substrate 11.
The optical fiber FOP can be inserted from the side through the coating groove 11f and the fiber groove 11e.

Then, after the inserted optical fiber FOP is butted against the built-in fiber 12, the wedge W is released from the concavity H. Then, in the ferrule 10,
Due to the spring force of the spring pin 15, the holding lids 13, 1
4 presses the optical fiber FOP against the upper surface of the ferrule substrate 11.

As a result, the inserted optical fiber FOP is very easily optically connected to the built-in fiber 12 in a stable and low-loss state. Moreover, the ferrule 10 allows anyone to easily connect the optical fiber by using a simple tool such as the wedge without any special processing facility. Then, the connected optical fiber can be easily pulled out from the ferrule 10 by prying the recess H with the wedge W in the same manner as described above.

Here, the ferrule 10 has a second half 11c.
In the case where the diameter of the outer circumference is small, as shown in FIG.
A semi-cylindrical auxiliary member 16 is arranged and a spring pin 15
Insert and assemble.

When an optical fiber is inserted into or pulled out of the ferrule 10 shown in FIG. 7, a wedge W is inserted into a concave portion H formed by the notch 13a of the holding cover 13 and the auxiliary member 16. In the same manner as above, the optical fiber can be easily inserted and the built-in fiber 12 can be inserted.
Can be connected or pulled out.

Next, the optical connector will be described. The optical connector 1 is constituted by using a ferrule 10, and as shown in FIG.
A spring 3 and a plug frame 4 are provided. Except for the structure of the ferrule 10, other components are JIS C 597.
3 Compatible with F04 type single core optical fiber connector.

The stop ring 2 is, as shown in FIG.
A cylindrical member having a slit 2a opened on the front edge side and a slit-shaped opening 2b formed substantially at the center in the longitudinal direction, and two circumferentially extending protrusions on the outer periphery adjacent to the slit 2a. 2c is provided. The stop ring 2 has a stepped portion 2d serving as a stopper for the spring 3 formed therein, and a knurled portion 2e provided on the outer periphery behind the stepped portion 2d.

The spring 3 has the shape shown in FIG.
It is manufactured based on the S standard and inserted into the stop ring 2. The spring 3 has a slit 2 a in the stop ring 2.
After the ferrule 10 is inserted from the side, the ferrule 10 is
When the ferrule 10 is inserted from the rear half 11c side, it is locked by the step 2d and urges the ferrule 10 toward the front slit 2a.

The plug frame 4 is a quadrangular prism-shaped member.
As shown in FIG. 11, a flange 11a of the ferrule substrate 11 is locked on the inner front side, a ridge 4a is formed so that a front half 11b protrudes forward, and a slit 4b is formed at a position corresponding to a slit at the rear. It is provided in. The plug frame 4 has slit-shaped locking holes 4 in the width direction on the upper and lower sides shown in FIG. 11 where the slits 4b are not formed.
c is formed.

The optical connector 1 configured as described above is
Assembled as shown in FIG.

That is, first, after the holding lid 13 and the holding lid 14 are fitted to the rear half 11c of the ferrule substrate 11 as described above, the spring pins 15 are fitted from the rear side.
The ferrule 10 shown in FIG. 1 is assembled.

Next, after the spring 3 is inserted into the stop ring 2 from the slit 2a side, the ferrule 10 is inserted from the rear half portion 11c side of the ferrule substrate 11.

Next, while pushing the ferrule 10 into the stop ring 2, the plug frame 4 is
Fit the stop ring 2 from the front side from the b side. Then, the plug frame 4 is fitted to the stop ring 2 in a state where the projections 2c are locked in the respective locking holes 4c, and the optical connector 1 is easily assembled.

Accordingly, the ferrule 10 is disposed between the ferrule substrate 11 and the stepped portion 2d of the stop ring 2 because the flange portion 11a of the ferrule substrate 11 is locked by the ridge 4a of the plug frame 4 so as to prevent the ferrule 10 from projecting forward. The optical connector 1 is held in a stable assembled state because it is urged toward the plug frame 4 by the spring 3.

At this time, when the optical fiber is connected to the assembled optical connector 1, as described above, the two concave portions H formed between the holding lids 13 and 14 of the ferrule 10 and the outer edge of the ferrule substrate 11 are wedges. If the optical fiber is inserted using the small gap formed between the holding lids 13 and 14, the connection with the built-in fiber 12 can be made extremely easily. Also, when pulling out the optical fiber, pull out by the reverse operation,
The optical fiber can be easily pulled out from the optical connector 1.

Here, the time required after assembling the optical connector 1 to obtain the pigtail type optical connector 1 to which the optical fiber was connected was measured. As a result, the assembly was easy within 2 minutes. Then, 100 pigtail type optical connectors 1 to which optical fibers were connected were prepared, and the connection loss and return loss of signal light transmitted from the outside were measured. The average was 0.3 dB or less and the average was 50 dB, respectively. It was confirmed that the above high characteristics were obtained, and characteristics not inferior to those of the conventional optical connector were obtained.

In addition, the optical connector 1 can be properly connected to another optical connector because the ferrule 10 is always urged forward by the spring 3 toward the connection side with a predetermined urging force.

On the other hand, like the ferrule 10 shown in FIG. 14, the holding cover 13 is formed so that both sides sandwiching the connection point C between the built-in fiber 12 and the inserted optical fiber FOP have the same length. I do. When the holding lid 13 is formed in this manner, it is preferable that when the holding lid 13 is fitted to the ferrule substrate 11, a pressing force acts uniformly from the spring pin 15 on the built-in fiber 12 and the inserted optical fiber FOP.

Further, as shown in FIG. 15A, the holding lid 13 may be formed with a recess 13b at a position corresponding to the position of the ferrule substrate 11 adjacent to the flange 11a on the upper surface of the rear half 11c. By providing the concave portion 13b, the pressing lid 13 can reduce the pressing force acting on the built-in fiber 12, thereby suppressing an increase in bending loss due to bending of the built-in fiber 12. On the other hand, the holding lid 14 is
(B) As shown in FIG.
4b may be formed. When the holding lid 14 is formed with the concave portion 14b, the holding lid 14 relaxes the optical fiber FOP to be inserted after being assembled to the ferrule 10 or the optical connector 1 so as not to exert an excessive pressing force, and reduces the tensile strength of the inserted optical fiber FOP. Can be increased.

On the other hand, the ferrule substrate 11 and the holding lid 13,
The holding member for elastically holding the spring 14 may be, for example, a spring pin 15 formed in a cylindrical shape, a shape slightly crushed in the vertical direction like a spring pin 17 shown in FIG. As in the case of the spring pin 18 shown in (b), in addition to the slit 18a formed over the entire length in the longitudinal direction, a part of the slit 18b may be formed so as to realize an appropriate pressing force. . FIG.
As in the case of a spring pin 19 shown in FIG. 6 (c), it may be formed into a semi-cylindrical shape, and a ridge 19a may be provided at a position where it comes into contact with the outer surfaces of the ferrule substrate 11 and the holding lids 13, 14.

Incidentally, in the ferrule 10, the axis of the fixing hole 11d and the axis of the fiber groove 11e may be shifted. When the built-in fiber 12 is inserted into the fiber groove 11e in such a state, the built-in fiber 12 is extremely bent, which may cause a bending loss. In order to suppress the occurrence of such bending loss,
As shown in FIGS. 13A and 13B, the ferrule substrate 11 preferably has a concave groove 11h formed at a position adjacent to the flange 11a on the upper surface of the rear half 11c. If the concave groove 11h is provided, the built-in fiber 12 located in the concave groove 11h portion
Becomes free. For this reason, ferrule 10
Even if the built-in fiber 12 is inserted into the fiber groove 11e in a state where the axes of the fixing hole 11d and the fiber groove 11e are not coincident, the displacement can be absorbed.
However, extreme bending is suppressed, and occurrence of bending loss can be suppressed.

Here, when the groove 11h is provided, the groove 1
If the length along the axis of the built-in fiber 12 of 1 h, that is, the length from the rear end of the fixing hole 11 d to the end of the fiber groove 11 e is short, the built-in fiber 12 is extremely bent, and the bending loss is reduced. The effect of suppressing is not so much exhibited.
For this reason, the fiber groove 11e extends from the rear end of the fixing hole 11d.
Is preferably set to be as long as possible.

However, in the ferrule 10, when the optical fiber FOP is inserted and butt against the built-in fiber 12 and both are connected by a mechanical splice method, the butt is confirmed by applying a pressing force to the built-in fiber 12. Therefore, even if the length from the rear end of the fixing hole 11d to the end of the fiber groove 11e is set too long, the built-in fiber 12 may buckle, bend, and be broken.

The present invention relates to a ferrule 10 and an optical connector 1.
In order to eliminate the above-mentioned problems and to provide high reliability, the ferrule and optical connector according to the present invention will be described below.

The ferrule of the present invention has the same structure as the ferrule 10 except that a hollow portion 21g is formed in the ferrule substrate 21, as shown in FIG. Therefore, in the following description, only the ferrule substrate 21 will be described, and portions common to the ferrule substrate 11 will be denoted by corresponding reference numerals and detailed description thereof will be omitted.
Also, the optical connector of the present invention has the same configuration as the optical connector 1 except that the ferrule substrate 21 is used.
Description is omitted.

The hollow portion 21g is provided with a concave groove 21h provided at a position adjacent to the flange portion 21a on the upper surface of the rear half portion 21c of the ferrule substrate 21, and a guide provided on the flange portion 21a side of the front half portion 21b of the ferrule substrate 21. It is formed by the hole 21i. Here, the space between the rear end of the fixing hole 21d and the end of the positioning groove 21e is defined as a hollow portion 21g, and the length thereof is defined as the hollow portion length L.

In the ferrule substrate 21, the fixing holes 2
One end of the built-in fiber 22 is inserted into 1d, and is adhesively fixed. The other end of the built-in fiber 22 extends from the fixing hole 21d, and a part of the built-in fiber 22 is placed in the fiber groove 21e. That is, the built-in fiber 22 is bridged between the fixing hole 21d and the fiber groove 21e. Then, the built-in fiber 22 covers the rear half 21c of the ferrule 20 with a holding lid (not shown),
The other end is fixed.

Here, the shaft of the fixing hole 21d and the fiber groove 2
1e, the built-in fiber 22 in the hollow portion 21g has a hollow portion length L, as shown in FIG.
It is assumed that both ends are displaced by the amount of axial deviation S and fixed at the distance of. At this time, the trajectory of the built-in fiber 22 in the hollow portion can be expressed by the following equation based on a model in which both ends of the optical fiber are fixed.

Y = S / 2 {1−cos (πx / L)} (1) On the other hand, the radius of curvature ρ of the built-in fiber 22 at the hollow portion length L can be expressed by the following expression based on a general expression. .

Ρ = {1+ (dy / dx) ² } ^3/2 / | d ² y / dx ² | (2) At this time, since both ends of the built-in fiber 22 are fixed, If one end is the origin on the coordinates,
By substituting x = 0 into the equation (2), the radius of curvature ρ at the origin can be obtained. That, (dy / dx) = ( πS / 2L) sin (πx / L) = 0 (d 2 y / dx 2) = (Sπ 2 / 2L 2) cos (πx / L)
= Sπ ² / 2L ² , so that ρ = 2L ² / Sπ ² (3)

Here, the fixing hole 21d and the fiber groove 21e
Is caused by accumulation of errors in the mold, but the maximum value is 0.02 (mm). Therefore, this value is substituted into the equation (3) to substitute the length L of the hollow portion and the radius of curvature. The relationship with ρ was determined, and the results are shown in FIG.

As is apparent from FIG. 19, the length L of the hollow portion
It can be understood that the radius of curvature ρ becomes larger as the value becomes larger. That is, as the length L of the hollow portion is set larger, the radius of curvature ρ becomes larger, the degree of bending becomes smaller, and the increase in bending loss is suppressed. At this time, according to the measurement by the present inventors, when the radius of curvature ρ is less than 5 (mm), the bending loss increases, so that the radius of curvature ρ is 5 (mm).
It is preferable to set the length of the hollow portion as described above.

However, in the present invention, JIS
In consideration of the structure of the ferrule based on the standard, the rigidity of the optical fiber, and the like, the length L of the hollow portion needs to be 2.5 mm or more. Therefore, the lower limit of the hollow portion length L is 2.5 (m
m). The length L of the hollow part is 2.5 (mm)
If there is, the radius of curvature is about 60 (mm), and the bending loss can be suppressed to a sufficiently low value.

On the other hand, when the value of the length L of the hollow portion increases,
As described above, the built-in fiber 2
2 causes buckling.

Therefore, in order to suppress the above problem as much as possible, a load at which buckling starts (hereinafter referred to as a buckling load) in order to determine an appropriate upper limit of the hollow portion length L at which buckling does not occur even when an optical fiber is inserted. The relationship between Pk and the length L of the hollow portion was studied as described below.

That is, first, the buckling load Pk (kg · f)
Is expressed by the following equation based on Euler's equation.

Pk = 4π ² EI / L ² (4) where L: length of hollow part (mm) E: elastic coefficient of optical fiber (7200 kg · f / mm ² ) I: second moment of area of optical fiber (Mm ⁴ ) I = (π / 64) d ⁴ d: diameter of optical fiber (mm) Here, for example, the diameter of the optical fiber is 0.125 (m).
m), the relationship between the length L of the hollow portion and the buckling load Pk was determined. The result is shown in FIG. As is clear from FIG. 20, the buckling load Pk decreases as the value of the length L of the hollow portion increases. That is, it is understood that the longer the hollow portion length L, the more the built-in fiber 22 buckles with a lower load.

According to the experiments of the present inventors, when assembling the optical connector, the optical fiber FOP is mounted on the fiber holder of the assembling apparatus, and the fiber holder is slid to insert the optical fiber FOP into the ferrule. As a result, it was confirmed that the optical fiber FOP was pushed in with a force of about 30 (g · f). Therefore, the built-in fiber 22 has 30
It is assumed that a pressing force of about (g · f) is applied. Here, in the present invention, as the maximum load applied to the built-in fiber 22, the safety factor is set to 1.5, and 30 ×
1.5 = 45 (g · f) was assumed. Therefore, from FIG. 20, when the length L of the hollow portion exceeds 8 (mm), 45 (g · f)
In the present invention, the length L of the hollow portion is set to 8 (mm) or less so that buckling does not occur even when a load of 45 (g · f) is applied. .

Therefore, the length L of the hollow portion in the ferrule or optical connector of the present invention is 2.5 (mm) ≦ L ≦ 8
(Mm).

As described above, when the hollow portion 21g is provided in the ferrule between the rear end portion of the fixing hole 21d and the end portion of the fiber groove 21e, and the length L of the hollow portion 21g is set in the above range, the fixing is performed. Even if the axis of the hole 21d and the axis of the fiber groove 21e are misaligned, the misalignment can be absorbed without increasing the bending loss, and at the time of assembling the optical connector, the built-in fiber is pressed by the inserted optical fiber. Buckling of the optical connector 22 in the hollow portion 21g can also be suppressed, and damage to the optical connector during assembly processing can be prevented. Therefore, the ferrule of the present invention and the optical connector incorporating the ferrule have high reliability because the built-in fiber does not excessively buckle.

The shape of the hollow portion 21g is not particularly limited, and a space capable of absorbing the displacement between the fixing hole 21d of the built-in fiber 22 and the axis of the fiber groove 21e can be secured. Any shape may be used as long as the distance (hollow portion length L) from the fiber groove 21e is within the above range, and a structure having only the guide hole 21i or a structure having only the concave groove 21h may be employed.

[0062]

According to the present invention, even if there is no processing facility,
A ferrule and an optical connector to which anyone can easily connect an optical fiber with a simple tool can be provided. In addition, the ferrule and the optical connector of the present invention are easy to assemble, can suppress excessive bending of the built-in fiber in the ferrule, can reduce bending loss, and can reduce the built-in fiber during assembly processing. Buckling can also be suppressed. For this reason,
A highly reliable optical transmission characteristic comparable to conventional ferrules and optical connectors can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a ferrule.

FIG. 2 is a plan view of a ferrule substrate constituting the ferrule of FIG. 1;

FIG. 3 is a sectional front view of the ferrule substrate of FIG. 2 cut along a longitudinal direction.

FIGS. 4A and 4B are side views (a) and (c) and plan views (b) and (d) of two types of lid members constituting the ferrule of FIG.

FIG. 5 is a perspective view of a holding member constituting the ferrule of FIG. 1;

FIG. 6 is a sectional view illustrating a procedure for inserting an optical fiber into the ferrule of FIG. 1;

FIG. 7 is a cross-sectional view showing a modification of the ferrule of FIG. 1 and illustrating a procedure for inserting an optical fiber.

FIG. 8 is a front view showing the optical connector in a cross section of a lower half.

FIG. 9 is a front view showing a cross section of a lower half of the stop ring constituting the optical connector of FIG. 8;

FIG. 10 is a front view of a spring used in the optical connector of FIG. 8;

11 is a front view showing a cross section of a lower half of a plug frame constituting the optical connector of FIG. 8;

FIG. 12 is an exploded view for explaining an assembling procedure of the optical connector of FIG. 8;

FIGS. 13A and 13B are a front view and a plan view showing a modified example of the ferrule substrate forming the ferrule and the optical connector.

FIG. 14 is a front view showing a modified example of the lid member constituting the ferrule and the optical connector, with the latter half of the ferrule being in cross section.

FIG. 15 is a perspective view showing another modification of the lid member constituting the ferrule and the optical connector.

FIG. 16 is a view showing a modified example of a holding member constituting a ferrule and an optical connector.

FIG. 17 is a sectional view of a ferrule substrate of the present invention.

FIG. 18 is a schematic configuration diagram showing a configuration of a built-in fiber fixed between a fixing hole whose axis is shifted and a fiber groove.

FIG. 19 is a graph showing the relationship between the length of the hollow portion and the radius of curvature.

FIG. 20 is a graph showing the relationship between the length of the hollow portion and the buckling load.

DESCRIPTION OF SYMBOLS 1 Optical connector 2 Stop ring 3 Spring 4 Plug frame 10 Ferrule 11 Ferrule board 11b First half 11c Second half 11d Fixing hole 11e Fiber groove (positioning groove) 12 Built-in fiber 13 Holding lid (lid member) 13a Notch 14 Holding lid (lid member) 14a Notch 15 Spring pin (holding member) 21 Ferrule substrate 21b First half 21c Second half 21d Fixing hole 21e Fiber groove (positioning groove) 21g Hollow part 22 Built-in fiber FOP Optical fiber H Concave part L Hollow part length W Wedge

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeyuki Nakano 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Takehiro Hayashi 2-6-1 Marunouchi, Chiyoda-ku, Tokyo No. Furukawa Electric Co., Ltd. (72) Kazuo Hokari, inventor 3--19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. No. 2 Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] An optical fiber fixing hole is formed in the front half, an upper half of the rear half is open, and an axis of the fixing hole is formed on a rear half upper surface. A ferrule substrate on which a positioning groove for positioning at least one optical fiber is formed coaxially and a built-in fiber whose rear half portion is mirror-cut in advance from the front end of the fixing hole to a part of the positioning groove is fixed; And a lid member attached to the rear half of the ferrule substrate and provided with a notch that forms a concave portion between the ferrule substrate and the outer edge of the ferrule substrate, and elastically holds the ferrule substrate and the lid member. A ferrule having a holding member, wherein a hollow portion is formed from a rear end of the fixing hole to an end of the positioning groove, and a length L of the hollow portion is 2.5 (mm) ≦ L
A ferrule characterized by being set in a range of ≦ 8 (mm). 2. An optical fiber fixing hole having a front half portion and a rear half portion, wherein the front half portion has an optical fiber fixing hole, and the rear half portion has an upper half opened, and the rear half portion upper surface has an axis line of the fixing hole. A ferrule substrate on which a positioning groove for positioning at least one optical fiber is formed coaxially and a built-in fiber whose rear half portion is mirror-cut in advance from the front end of the fixing hole to a part of the positioning groove is fixed; And a lid member attached to the rear half of the ferrule substrate and provided with a notch that forms a concave portion between the ferrule substrate and the outer edge of the ferrule substrate, and elastically holds the ferrule substrate and the lid member. A hollow portion is formed between the rear end of the fixing hole and the end of the positioning groove, and the length L of the hollow portion is 2.5 (mm) ≦ L ≦ 8 ( mm) A stop ring for inserting the ferrule having a predetermined clearance between the rule and the inner surface of the stop ring via a spring; and a plug frame for attaching the stop ring to the stop ring and holding the ferrule. Optical connector characterized by the above-mentioned.