JPH07333126A - Strength testing apparatus and method for optical fiber - Google Patents

Abstract

PURPOSE:To provide a testing apparatus which carries out a durable strength property test for an optical fiber by measuring the time until the optical fiber is ruptured in the condition where a prescribed load is applied intermittently to the optical fiber. CONSTITUTION:A strength testing apparatus for optical fibers is provided with at least an upper part chuck 2 and a lower part chuck 3 which fix and hold both end parts of an optical fiber F and extend the optical fiber in the longitudinal direction, a stepping motor 6 to apply twisting force to the optical fiber, and a timer 10 which starts when the optical fiber is twisted a prescribed number of times by the stepping motor, keeps the condition as it is, and corresponds the lower part chuck 3 which moves by rupturing the optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber strength test apparatus and method.

[0002]

2. Description of the Related Art Since an optical fiber has a weak mechanical strength, it is necessary to grasp the strength characteristics of the optical fiber in advance when laying an optical fiber cable using the optical fiber. Therefore, as a conventional twist characteristic test apparatus for examining the strength characteristic of an optical fiber, for example, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent Publication No. -13361. The one disclosed in this publication is movable along one straight line, and one end of an optical fiber to be measured is fixed to one end of a twisting rotating body which is rotatably supported in a plane perpendicular to the straight line, One end of a flexible linear member is attached to the other end of the twisting rotary member, the other end of the optical fiber is fixed, and the optical fiber is greatly variable in the linear direction with respect to the twisting rotary member via the linear member. Is applied to stretch the optical fiber along the straight line, and the optical fiber is twisted around the straight line. The test apparatus is configured to measure the number of twists and the torque around the straight line of the twisting rotating body in a state where the tensile force of the optical fiber is changed by the above configuration.

[0003]

However, in the above-mentioned conventional test apparatus, although various tensions can be changed, the measurement test is conducted under the condition that the tensile force is constant and the number of twists and twists until the optical fiber is broken. The stress (torque) was measured, and the strength was measured against short-term twist of the optical fiber. However, in actual use of the optical fiber, it is essential to measure the long-term strength reliability with aging, and it is not enough to measure the short-term strength as described above. The present invention has been proposed in view of the above circumstances, and long-term strength characteristics of an optical fiber can be obtained by measuring the time until breakage in a state where a predetermined load is continuously applied to the optical fiber. An object is to provide an optical fiber strength test apparatus and method.

[0004]

In order to achieve the above object, the structure of an optical fiber strength test apparatus according to the present invention comprises a fixing means for holding at least both ends of the optical fiber in the longitudinal direction, and the optical fiber. And a timer means that responds to the fixing means that is displaced by twisting the optical fiber a predetermined number of times by the twisting means and holding the state and breaking the optical fiber. Is. Furthermore, the optical fiber strength test apparatus according to the present invention comprises an upper chuck and a lower chuck that hold both ends of the optical fiber in the longitudinal direction, a stepping motor that is connected to the upper chuck and applies a twist to the optical fiber, It can be embodied by a timer equipped with a timer which starts when the optical fiber is rotated a predetermined number of times by the stepping motor, and which stops in response to the lower chuck that falls by holding the state and breaking the optical fiber.

Further, in the strength test method for an optical fiber according to the present invention, both longitudinal ends of the optical fiber are fixedly held by a chuck, and when the optical fiber is rotated a predetermined number of times, a timer is started, Is kept in that state and broken, and the timer is stopped by the breaking of the optical fiber to measure the time.

[0006]

[Operation] With the above structure, both ends of the optical fiber are fixed to the upper chuck and the lower chuck, respectively, and the optical fiber is twisted by the twisting means while the optical fiber is held in the longitudinal direction. Then, when a tensile stress is applied in the longitudinal direction by rotating the optical fiber a predetermined number of times, a timer is started, and the optical fiber is left as it is until it breaks while maintaining that state. When the optical fiber breaks, the timer stops in response to the lower chuck that drops with the break, so that the time from when a constant load is applied to the optical fiber until the break can be measured.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an optical fiber strength test apparatus according to an embodiment of the present invention. The device body 1 is a base 1
a, a pair of columns 1c standing upright on both ends of the base 1a, and a top plate 1b installed on the columns 1c. An upper chuck 2 serving as a fixing means for an optical fiber is rotatably supported on a top plate 1b by being connected to a rotating shaft 6a of a stepping motor 6 described later, and is arranged corresponding to the upper chuck 2. The lower chuck 3, which serves as a fixing means for the optical fiber, is fixed to the mounting plate 5 together with the upper chuck 2. The mounting plate 5 is provided inside the pillar 1c so as to engage with a pair of guide rods 4 projecting from the base 1a and to be vertically movable along the guide rods 4. The mounting plate 5 is provided with a stopper 9 at an engaging portion with the guide rod 4, and the stopper 9 serves as the mounting plate 5.
The upward movement at a predetermined position on the guide rod 4 is restricted, and the downward movement is allowed. The upper chuck 2 and the lower chuck 3 hold both ends of the optical fiber F as a sample, and hold the optical fiber F in a fixed manner.

On the top plate 1b, connected to the upper chuck 2,
A stepping motor 6 as a twisting means for twisting the optical fiber F is provided. The stepping motor 6 applies a stress to the optical fiber F in the twisting direction, and at the same time, the mounting plate 5 whose upward movement is restricted has a reaction force against the optical fiber F contracting in the longitudinal direction due to the twisting. Therefore, a tensile stress action in the longitudinal direction can be applied to the optical fiber F. A controller 12 is connected to the stepping motor 6, and a counter 7 and a rotary encoder 8 provided near the rotating shaft 6a are connected to the controller 12. The counter 7 can set the twisting rotation speed for the optical fiber F in advance, and the controller 12 constantly compares the rotation speed measurement value of the rotary shaft 6a detected by the rotary encoder 8 with the counter setting value to set the stepping motor 6. Is configured to control. When the rotation speed measurement value of the rotation shaft 6a connected to the upper chuck 2 reaches the counter setting value, the stepping motor 6
Is controlled to stop rotating.

Further, in this strength test apparatus, the continuity sensor 11 is arranged on the base 1a below the mounting plate 5. The continuity sensor 11 responds to the mounting plate 5 that drops downward due to the breakage of the optical fiber F when the breakage of the optical fiber F occurs due to the optical fiber F being rotated a predetermined number of times and being kept in that state. It outputs a conduction signal and is connected to a timer 10 as a timer means for measuring the time until the mounting plate 5 is displaced. The timer 10 is also connected to the stepping motor 6 and the stepping motor 6
Is started and the rotation is stopped, the clocking is started, and the clocking is stopped in response to the conduction signal. A general micro switch, a photoelectric switch, or the like can be used as the continuity sensor 11.

Next, a test method based on the strength test apparatus according to the present invention will be described. FIG. 2 is a flow chart showing the measurement procedure of the test apparatus according to the present invention. First,
The counter 7 is set to a specified number of times, for example, about 5 to 50 times, and the set value of the number of twists of the optical fiber F is input (step 110). Upon completion of inputting the set value, the optical fiber F having a predetermined length as a sample is attached to the upper chuck 2
And the lower chuck 3 are fixedly held (step 120). When the start button is turned on (step 130), the operation of the stepping motor 6 is started, and the stepping motor 6 is rotated at a constant speed to twist the optical fiber F (step 140). The rotary encoder 8 constantly measures the rotation speed of the upper chuck 2 (step 150). The controller 12 compares the set value input in advance to the counter 7 with the measured value from the rotary encoder 8 and drives the stepping motor 6 until both values match (step 16).
0). When the set value and the measured value match, the stepping motor 6 is stopped (step 170). When the motor stops, the fracture measurement starts, and the timer 10 starts counting time (step 180). The optical fiber F is continuously maintained in the above state until it is broken. Breakage of the optical fiber F is detected by the lower chuck 3 dropping and the continuity sensor 11 outputting a continuity signal (step 190).
The above state is further continuously maintained while the conduction signal is not detected, and when it is detected, the timer 10 is stopped (step 2).
00). Through the series of steps, the break time of the optical fiber F clocked by the timer 10 is recorded (step 210). The above steps 120 to 210 are
The measurement is performed on 15 or more samples, that is, the breaking time of each sample is repeatedly measured under the same number of twists (step 220). Further, in the above series of measurements, the number of twists is changed, that is, the number of times the counter 7 is set is reset to, for example, four conditions or more, and 1
Repeat for 5 or more samples each.

The above steps 130 to 200 are carried out by automating the apparatus, whereby the error of the measurer can be prevented and the labor can be saved.

FIG. 3 is a graph showing the measurement result of the above-mentioned breaking time, and the long-term reliability is evaluated by obtaining the slope of the straight line.
In that case, log ΔT (sec) / Δ number of times = 0.3 to
If it is 0.8, it can be evaluated as usable.

[0013]

According to the optical fiber strength testing apparatus and its testing method of the present invention, both ends of the optical fiber are fixedly held by the upper chuck and the lower chuck, which are fixing means, and the optical fiber is twisted by the twisting means. By applying a twist, a tensile force is applied in the longitudinal direction. And
The optical fiber is rotated a predetermined number of times to continuously maintain its state, and the time from when the load is applied to the optical fiber to when the optical fiber is broken is measured by a timer means. As a result, this strength tester can evaluate the long-term reliability of strength against the complicated load applied to the optical fiber,
This is useful for ensuring the long-term reliability of the optical fiber cable. Further, since the device configuration is simple, the size can be easily reduced, and the test can be performed under a special environment such as low temperature.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical fiber strength test apparatus according to the present invention.

FIG. 2 is a flowchart showing a measurement procedure of the optical fiber strength test method of the present invention.

FIG. 3 is a diagram showing an evaluation method by the test apparatus of the present invention.

[Explanation of symbols]

 2 Upper chuck 3 Lower chuck 5 Mounting plate 6 Stepping motor 7 Counter 8 Rotary encoder 10 Timer 11 Continuity sensor F Optical fiber

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[Procedure amendment]

[Submission date] September 29, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The steps 140 to 200 are carried out by automating the apparatus, which can prevent the error of the measurer from occurring and save labor.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (3)

[Claims] 1. A fixing means for holding at least both ends of an optical fiber in a longitudinal direction, a twisting means for applying a twist to the optical fiber, and the twisting means for twisting the optical fiber a predetermined number of times and holding the state. And a timer means that responds to the fixing means that is displaced by breaking the optical fiber. 2. An upper chuck and a lower chuck that hold both ends of the optical fiber in a longitudinal direction, a stepping motor that is connected to the upper chuck and twists the optical fiber, and the optical fiber is predetermined by the stepping motor. An optical fiber strength test apparatus, comprising: a timer that starts when it is rotated a number of times, and that stops in response to the lower chuck that drops by holding and breaking the state. 3. The longitudinal ends of the optical fiber are fixedly held by an upper chuck and a lower chuck, respectively, and a timer is started when the optical fiber is rotated a predetermined number of times, and the optical fiber is held in that state and broken. A method for testing the strength of an optical fiber, wherein the timer is stopped and the time is measured by breaking the optical fiber.