Optical fiber cutting device and optical fiber cutting method

Abstract

The optical fiber cutting device of the present invention includes a pair of gripping parts for gripping an optical fiber having an exposed glass portion, a gripping force applying part capable of changing the gripping force, a tension applying part for applying tension to the optical fiber, a tension measuring sensor for measuring the tension, a control part for controlling the gripping force, and a blade for applying scratches to the optical fiber. The control part determines a set gripping force based on a minimum non-slip gripping force that is the minimum gripping force with which at least one of the pair of gripping parts can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber. At least one of the pair of gripping parts applies tension to the optical fiber while gripping the optical fiber with the set gripping force, and cuts the optical fiber by applying scratches to the optical fiber with the blade.

Description

[Technical Field]

[0001] The present invention relates to an optical fiber cutting device and an optical fiber cutting method. This application claims priority based on Japanese Patent Application No. 2021-086140, filed on May 21, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Patent Document 1 discloses an optical fiber cutting device that holds an optical fiber with two gripping parts, applies tension to the optical fiber, and presses a blade against a glass part to cut the optical fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-90943 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of extensive research by the inventors of the present application, it has been found that if the gripping force on the optical fiber is too strong, the desired cut surface cannot be obtained when cutting, and if the gripping force on the optical fiber is too weak, slippage occurs between the optical fiber and the gripping part, preventing the application of appropriate tension.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an optical fiber cutting device and an optical fiber cutting method that can cut an optical fiber well by holding the optical fiber with an appropriate gripping force. [Means for solving the problem]

[0006] In order to solve the above problems, an optical fiber cutting device according to one aspect of the present invention includes a pair of gripping units that grip an optical fiber having a portion where the glass portion is exposed; a gripping force applying unit that is provided on at least one of the pair of gripping units and is capable of changing the gripping force; a tension applying unit that applies tension to the optical fiber by moving the pair of gripping units away from each other along the longitudinal direction of the optical fiber; a tension measurement sensor that measures the tension; a control unit that controls the gripping force applied by the gripping force applying unit; and a blade that is located between the pair of gripping units in the longitudinal direction and that applies a scratch to the portion of the optical fiber where the glass portion is exposed. The control unit determines a set gripping force based on a minimum non-slip gripping force, which is the minimum gripping force that at least one of the pair of gripping units can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber, and when at least one of the pair of gripping units is holding the optical fiber with the set gripping force, tension is applied to the optical fiber and the optical fiber is scratched by the blade to cut it.

[0007] According to the above aspect, when cleaving an optical fiber, the optical fiber is gripped with a set gripping force determined based on the minimum non-slip gripping force. This prevents the gripping force on the optical fiber from becoming excessively large when cleaving the optical fiber, thereby suppressing an increase in the cut surface angle of the optical fiber. It also prevents slippage of the optical fiber caused by insufficient gripping force during cleaving. Conventionally, the magnitude of the gripping force has sometimes been determined based on the experience and intuition of the operator. In contrast, by determining the set gripping force based on the minimum non-slip gripping force, as in the optical fiber cleaving device of the above aspect, it is possible to suppress variations in cleaving operation between operators, enabling more stable and successful cleaving of the optical fiber.

[0008] Here, the optical fiber cutting device of the above aspect may be provided with a memory unit that stores at least one of the minimum non-slip gripping force, the set gripping force, a control value for applying the minimum non-slip gripping force, and a control value for applying the set gripping force.

[0009] In the optical fiber cutting device of the above aspect, the gripping force imparting unit may include a first gripping force imparting unit capable of changing the gripping force of one of the pair of gripping units, and a second gripping force imparting unit capable of changing the gripping force of the other of the pair of gripping units. The control unit may control the gripping force generated by the first gripping force imparting unit and the gripping force generated by the second gripping force imparting unit.

[0010] Here, in the optical fiber cutting device of the above aspect, the control unit may control the gripping force generated by the first gripping force applying unit and the gripping force generated by the second gripping force applying unit so that they are equal to each other.

[0011] In this case, by storing the minimum non-slip gripping force, etc. in the memory unit, the minimum non-slip gripping force, etc. can be read out and used in subsequent operations. It is thought that the minimum non-slip gripping force will be approximately the same for optical fibers of the same type. In other words, once the minimum non-slip gripping force is measured, when subsequently cutting optical fibers of the same type, an appropriate gripping force can be obtained by adopting a set gripping force based on the same minimum non-slip gripping force value. This can therefore increase the efficiency of repeated optical fiber cutting.

[0012] In addition, an optical fiber cutting method according to one embodiment of the present invention includes gripping an optical fiber having an exposed glass portion with a first gripping portion and a second gripping portion, and moving the first gripping portion and the second gripping portion away from each other along the longitudinal direction of the optical fiber while changing the gripping force of the first gripping portion to determine a minimum non-slip gripping force, which is the minimum gripping force with which the first gripping portion can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber, and gripping the optical fiber with the first gripping portion at a set gripping force determined based on the minimum non-slip gripping force, and applying a blade to the exposed glass portion of the optical fiber located between the first gripping portion and the second gripping portion to cut the optical fiber.

[0013] According to the optical fiber cutting method of the above aspect, the optical fiber can be gripped and cut with an appropriate gripping force, similar to the optical fiber cutting device described above.

[0014] In the optical fiber cutting method according to the above aspect, the optical fiber may be gripped so as to cause slippage in the first gripping portion, and while increasing the gripping force of the first gripping portion, the first gripping portion and the second gripping portion are moved away from each other along the longitudinal direction of the optical fiber, and the gripping force when the tension applied to the optical fiber reaches a predetermined threshold may be defined as the minimum non-slip gripping force.

[0015] In this case, when measuring the minimum non-slip gripping force, it is possible to prevent a large gripping force from being applied to the optical fiber coating, which would cause plastic deformation. Therefore, after measuring the minimum non-slip gripping force, it is possible to cut the optical fiber directly and reuse the cut optical fiber.

[0016] Furthermore, in the optical fiber cutting method according to the above aspect, the optical fiber may be gripped by the first gripping portion so as not to cause slippage, and the first gripping portion and the second gripping portion may be moved away from each other along the longitudinal direction of the optical fiber while reducing the gripping force of the first gripping portion, and the gripping force when slippage occurs between the first gripping portion and the optical fiber may be defined as the minimum non-slip gripping force.

[0017] In this case, the stroke required to separate the pair of gripping sections from each other when measuring the minimum non-slip gripping force can be reduced. More specifically, once the slack in the optical fiber between the pair of gripping sections is eliminated and tension is applied to the optical fiber, there is no need to move the gripping sections relative to each other any further. Therefore, the longitudinal size of the optical fiber cutting device can be reduced, and the time required to measure the minimum non-slip gripping force can also be shortened.

[0018] Here, in the optical fiber cutting method according to the above aspect, the minimum non-slip gripping force may be determined by varying the gripping force of the first gripping portion and the gripping force of the second gripping portion while moving the first gripping portion and the second gripping portion away from each other along the longitudinal direction of the optical fiber.

[0019] Here, in the optical fiber cutting method according to the above aspect, the gripping force of the first gripping portion and the gripping force of the second gripping portion may be changed so that the gripping force of the first gripping portion and the gripping force of the second gripping portion are equal to each other. [Effects of the Invention]

[0020] According to the above aspects of the present invention, it is possible to provide an optical fiber cutting device and an optical fiber cutting method that can cut an optical fiber well by gripping the optical fiber with an appropriate gripping force. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view showing an optical fiber cutting device according to a first embodiment. [Figure 2] 10 is a flowchart showing a gripping force deriving process according to the first embodiment. [Figure 3] 10 is a graph showing the relationship between the gripping force and the end face angle of the cleaved optical fiber. [Figure 4] 10 is a flowchart showing a gripping force deriving process according to the second embodiment. [Figure 5] FIG. 10 is a perspective view showing an optical fiber cutting device according to a third embodiment. [Figure 6] 11 is a flowchart showing a gripping force deriving process according to the third embodiment. [Figure 7] 10 is a flowchart showing a gripping force deriving process according to the fourth embodiment. [Figure 8] 13 is a flowchart showing a gripping force deriving process according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) The optical fiber cutting device of the first embodiment will be described below with reference to the drawings. 1, the optical fiber cutting device 1 includes a base 2, a tension applying unit A, a tension measuring sensor 6, a blade 7, a control unit 8, a first gripping unit 10, and a second gripping unit 20. The first gripping unit 10 and the second gripping unit 20 are each configured to grip a single optical fiber F at different locations.

[0023] The optical fiber F has a glass portion f1 and a coating f2 that covers the glass portion f1. The coating f2 is made of a material such as resin. In the portion of the optical fiber F located between the first gripping unit 10 and the second gripping unit 20, the coating f2 is removed from at least a portion of the optical fiber F, exposing the glass portion f1. With the first gripping unit 10 and the second gripping unit 20 applying a predetermined tension to the optical fiber F, the blade 7 is brought into contact with the glass portion f1, thereby cutting the optical fiber F.

[0024] (direction definition) In this embodiment, the longitudinal direction of the optical fiber F is simply referred to as the longitudinal direction X. The longitudinal direction X is also the direction in which the first gripping portion 10 and the second gripping portion 20 are arranged. With respect to the positions in the longitudinal direction X where the two gripping portions are arranged, the first gripping portion 10 side is referred to as the +X side, and the second gripping portion 20 side is referred to as the -X side. A direction perpendicular to the longitudinal direction X is referred to as the vertical direction Z. One side (+Z side) in the vertical direction Z is referred to as the upper side, and the opposite side (-Z side) is referred to as the lower side.

[0025] The first gripping portion 10 and the second gripping portion 20 are arranged at an interval in the longitudinal direction X. The first gripping portion 10 is movable in the longitudinal direction X relative to the base 2, and the second gripping portion 20 is fixed to the base 2. Therefore, the first gripping portion 10 is movable in the longitudinal direction X relative to the second gripping portion 20.

[0026] The first gripping unit 10 includes a first mounting table 11, a first lid 12, a first hinge 13, and a first gripping force applying unit 14. The first lid 12 is rotatably connected to the first mounting table 11 by the first hinge 13. The first mounting table 11 and the first lid 12 are configured to grip the optical fiber F by a gripping force generated by the first gripping force applying unit 14. A fiber groove extending along the longitudinal direction X and recessed downward is formed in the first mounting table 11. The first gripping force applying unit 14 includes a pressing actuator (not shown) such as a motor and a gear train that transmits the power of the pressing actuator to the first lid 12. Although detailed description will be omitted, when the pressing actuator of the first gripping force applying unit 14 is activated, the power is transmitted to the first lid 12 via the gear train, and a downward force is applied to the first lid 12. This force becomes the gripping force with which the first gripping portion 10 grips the optical fiber F. The configuration of the first gripping force imparting portion 14 is not limited to the configuration of this embodiment and can be modified as appropriate as long as it can change the gripping force.

[0027] The second gripping unit 20 has a second mounting table 21, a second lid 22, and a second hinge 23. The second lid 22 is rotatably connected to the second mounting table 21 by the second hinge 23. The second mounting table 21 and the second lid 22 are configured to grip the optical fiber F with a predetermined gripping force. The gripping force of the second mounting table 21 and the second lid 22 may be generated by, for example, a spring, or may be generated by a pressure-applying actuator and a gear train similar to those of the first gripping unit 10. The second mounting table 21 has a fiber groove formed therein that extends along the longitudinal direction X and is recessed downward.

[0028] 1, in this embodiment, the coating f2 is removed from the entire optical fiber F from the end on the -X side to the portion between the first gripping part 10 and the second gripping part 20. The first gripping part 10 grips the coating f2. The second gripping part 20 grips the glass part f1.

[0029] The tension applying unit A has a gripper movement actuator 3, a shaft 4, and a movable base 5. The gripper movement actuator 3 is fixed to the base 2 and can move the shaft 4 in the longitudinal direction X. For example, a linear motor can be used as the gripper movement actuator 3. The shaft 4 extends along the longitudinal direction X. The movable base 5 is fixed to the end of the shaft 4 on the -X side. When the gripper movement actuator 3 is actuated, the shaft 4 and the movable base 5 slide relative to the base 2 in the longitudinal direction X. A slide rail or the like may be provided between the movable base 5 and the base 2.

[0030] The movable base 5 supports a first mounting table 11. A slide rail 5a is provided between the movable base 5 and the first mounting table 11. This allows the first mounting table 11 to move relative to the movable base 5 along the longitudinal direction X. In this embodiment, the tension measuring sensor 6 is sandwiched between the first mounting table 11 and the movable base 5. A specific type of tension measuring sensor 6 may be, for example, a load cell. When the gripper movement actuator 3 moves the shaft 4 toward the +X side, a force toward the +X side acts on the first mounting table 11 via the tension measuring sensor 6. At this time, if the first gripper 10 and the second gripper 20 are gripping the optical fiber F, the optical fiber F is pulled between the first gripper 10 and the second gripper 20. A compressive force corresponding to the tension in the optical fiber F is then applied to the tension measuring sensor 6. Therefore, the tension in the optical fiber F can be calculated based on the compressive force measured by the tension measuring sensor 6. As long as the tension of the optical fiber F can be measured, the structure and arrangement of the tension measuring sensor 6 may be changed as appropriate.

[0031] The blade 7 is supported by a support (not shown) and can move in a direction perpendicular to the longitudinal direction X relative to the optical fiber F. That is, the blade 7 can move toward or away from the optical fiber F. In the example shown in FIG. 1 , the blade 7 moves in a direction perpendicular to both the longitudinal direction X and the vertical direction Z. However, the blade 7 may also move in the vertical direction Z or in a direction oblique to the vertical direction Z.

[0032] The control unit 8 controls the gripper movement actuator 3 and the first gripping force imparting unit 14. As the control unit 8, for example, an integrated circuit such as a microcontroller, an IC (Integrated Circuit), an LSI (Large-scale Integrated Circuit), or an ASIC (Application Specific Integrated Circuit) can be used.

[0033] The control unit 8 can control the gripping force with which the first gripping unit 10 grips the optical fiber F by driving the pressure-imparting actuator of the first gripping force imparting unit 14. When controlling the gripping force, the control unit 8 may, for example, calculate the gripping force by back-calculating from the drive amount of the pressure-imparting actuator. Alternatively, a pressure sensor may be provided in the first gripping unit 10, and feedback control may be performed based on the output from the pressure sensor.

[0034] Next, a method for cutting the optical fiber F by the optical fiber cutting device 1 will be described.

[0035] When cutting the optical fiber F using the optical fiber cutting device 1, a gripping force deriving step, a gripping step, and a cutting step are performed. In the gripping force deriving step, a minimum non-slip gripping force is derived. The minimum non-slip gripping force is the minimum value of the gripping force required to grip the coating f2 in order to apply a predetermined tension to the optical fiber F. In the gripping step, the optical fiber F is gripped by the first gripping unit 10 and the second gripping unit 20. At this time, at least the first gripping unit 10 grips the coating f2 of the optical fiber F with a set gripping force determined based on the minimum non-slip gripping force. The second gripping unit 20 grips the glass portion f1 exposed by removing the coating f2 of the optical fiber F. In other words, the optical fiber F has a portion where the glass portion f1 is exposed. The portion where the glass portion f1 is exposed may be referred to as the exposed glass portion. In the cutting process, the optical fiber F is held by the first gripping unit 10 and the second gripping unit 20, and the blade 7 is pressed against the glass portion f1 while a predetermined tension is applied to the optical fiber F. This causes an initial flaw in the glass portion f1, which then breaks from this initial flaw, thereby cutting the optical fiber F.

[0036] Next, the gripping force deriving step in this embodiment will be described with reference to FIG. First, the glass portion f1 of the optical fiber F is gripped by the second gripping portion 20 (step S1). The gripping force at this time is set to a sufficiently strong force (hereinafter referred to as the "non-slip gripping force") that prevents slippage between the second gripping portion 20 and the glass portion f1 of the optical fiber F when tension is applied to the optical fiber F. The magnitude of the non-slip gripping force can be determined by a preliminary experiment, for example. For example, if the outer diameter of the glass portion f1 is 250 μm, the non-slip gripping force can be set to 3 kgf. Note that the glass portion f1 has a higher rigidity than the coating f2 and is less likely to deform. For this reason, it is easy to set a non-slip gripping force that prevents slippage and deformation of the glass portion f1.

[0037] Next, the optical fiber F is gripped by the first gripping unit 10 (step S2). The gripping force at this time is set to be sufficiently weak (hereinafter referred to as "micro-gripping force") that causes slippage between the first gripping unit 10 and the coating f2 of the optical fiber F when tension is applied to the optical fiber F. The micro-gripping force is generated by the control unit 8 controlling the pressure-imparting actuator of the first gripping force imparting unit 14. The magnitude of the micro-gripping force may be the minimum value that can be set (for example, approximately 0 gf).

[0038] Next, the control unit 8 drives the gripping unit movement actuator 3 to move the first gripping unit 10 in a direction (+X side) away from the second gripping unit 20 (step S3). At this point, the first gripping unit 10 grips the coating f2 with a small gripping force, causing slippage between the first gripping unit 10 and the coating f2. Therefore, no tension acts on the optical fiber F, or a small tension acts on the optical fiber F due to friction between the first gripping unit 10 and the coating f2. The tension on the optical fiber F is measured by the tension measurement sensor 6 at any time.

[0039] Next, the control unit 8 drives the pressure applying actuator of the first gripping force applying unit 14 so that the gripping force of the first gripping unit 10 on the coating f2 gradually increases (step S4). As the gripping force of the first gripping unit 10 increases, the friction between the first gripping unit 10 and the coating f2 increases, and the tension acting on the optical fiber F increases. In other words, the magnitude of the tension of the optical fiber F measured by the tension measuring sensor 6 increases. The increase in the gripping force of the first gripping unit 10 continues until it is stopped in step S6, which will be described later.

[0040] Next, the control unit 8 determines whether the tension (reading value) of the optical fiber F measured by the tension measuring sensor 6 has reached a predetermined threshold (step S5). The "predetermined threshold" is the appropriate magnitude of tension to be applied to the optical fiber F when cutting the optical fiber F. The magnitude of the "predetermined threshold" varies depending on the type of optical fiber F (e.g., the optical fiber type, product model number, specifications, etc.) and can be determined through preliminary experiments, etc. For example, for an optical fiber F made of quartz glass without a cavity and having an outer diameter of the glass portion f1 of 125 μm, the "predetermined threshold" should be 200 gf. Furthermore, for an optical fiber F having an outer diameter of the glass portion f1 of 400 μm, the "predetermined threshold" should be 1 kgf.

[0041] If the tension of the optical fiber F measured by the tension measuring sensor 6 is smaller than the predetermined threshold value (step S5: NO), the control unit 8 repeatedly performs the determination of step S5. As time passes, the gripping force of the first gripping unit 10 increases, and therefore the tension of the optical fiber F measured by the tension measuring sensor 6 also increases. If the tension of the optical fiber F measured by the tension measuring sensor 6 reaches the predetermined threshold value (step S5: YES), the process proceeds to step S6. The magnitude of the gripping force by the first gripping unit 10 at this time is the minimum gripping force with which the first gripping unit 10 can grip the optical fiber F without slipping when a tension of the predetermined threshold value is applied to the optical fiber F (hereinafter referred to as the "minimum non-slip gripping force").

[0042] In step S6, the control unit 8 stops the pressure applying actuator and the gripping unit movement actuator 3 of the first gripping force applying unit 14 and maintains (holds) this state. This stops the movement of the first gripping unit 10 toward the +X side and the increase in the gripping force of the first gripping unit 10. Therefore, the increase in the tension acting on the optical fiber F also stops.

[0043] Next, the control unit 8 stores the gripping force of the first gripping unit 10 at that time in the memory unit as the minimum non-slip gripping force (step S7). The memory unit may be provided inside the control unit 8 or outside the control unit 8. The memory unit may be a rewritable memory (RAM: Random Access Memory, flash memory, etc.). This completes the gripping force derivation process. Note that in step S7, the minimum non-slip gripping force itself may be stored, or a control value for applying the minimum non-slip gripping force may be stored. For example, if the pressure-applying actuator is a motor, the "control value for applying the minimum non-slip gripping force" is the current value of the motor at the time of step S7. Also, in step S7, the memory unit may store a set gripping force determined based on the minimum non-slip gripping force. Alternatively, the memory unit may store a control value (e.g., a motor current value) for applying the set gripping force. In this specification, "at least one of the minimum non-slip gripping force, the set gripping force, the control value for applying the minimum non-slip gripping force, and the control value for applying the set gripping force" may be simply referred to as "minimum non-slip gripping force, etc."

[0044] After step S7 is completed, the cutting step may be performed in that state. In this case, the gripping step described above is included in the gripping force deriving step. More specifically, step S6 corresponds to the gripping step. Alternatively, after step S7 is completed, another optical fiber F of the same type may be reset in the optical fiber cutting device 1, and the gripping and cutting steps may be performed. In this case, a force greater than the obtained minimum non-slip gripping force may be set as the set gripping force of the first gripping unit 10. The reason for this will be described later. Note that the "set gripping force" in this specification refers to the set value of the gripping force with which the first gripping unit 10 or the second gripping unit 20 grips the optical fiber F, determined based on the minimum non-slip gripping force.

[0045] (Experimental example) Next, the reason why the above cutting method can obtain an appropriate cut surface will be explained using the results of an experiment shown in FIG.

[0046] In this experimental example, multiple optical fibers F were prepared and cut while varying the magnitude of the gripping force applied to the coating f2. The relationship between the gripping force and the inclination angle of the cut surface was investigated. The gripping force was varied from 0 to +2000 gf relative to the minimum non-slip gripping force. The horizontal axis of Figure 3 shows the gripping force applied to the coating f2 as an offset value relative to the minimum non-slip gripping force. The vertical axis of Figure 3 shows the angle of the cut surface (end face) relative to a plane perpendicular to the longitudinal direction X when the optical fiber F was cut while being held with each gripping force. The smaller the end face angle, the smaller the optical connection loss when the optical fiber F is fusion spliced ​​or when the optical fiber F is butted against another optical system.

[0047] As shown in Figure 3, the greater the gripping force, the greater the end face angle. This is thought to be because gripping the coating f2 with excessive force causes the coating f2 to undergo significant compressive deformation and the glass portion f1 of the optical fiber F to bend at an angle relative to the longitudinal direction X. More specifically, when the coating f2 is compressively deformed by, for example, the first gripping unit 10, bending stress is generated in the coating f2 at the boundary between the portion gripped by the first gripping unit 10 and the portion not gripped. The greater the gripping force, the greater this bending stress, making the optical fiber F more likely to bend. As a result, the end face angle becomes larger.

[0048] According to the results in Figure 3, when the gripping force was in the range of 0 to +1000 gf relative to the minimum non-slip gripping force, the end face angle could be kept below 0.5°. Furthermore, when the gripping force was in the range of 0 to +500 gf relative to the minimum non-slip gripping force, the end face angle could be kept below 0.3°. In this way, it was confirmed that the end face angle could be reduced by bringing the gripping force closer to the minimum non-slip gripping force.

[0049] However, due to variations in the mechanical operation of the first gripping unit 10 or the second gripping unit 20, the magnitude of the actual gripping force may not be constant each time the optical fiber F is gripped, even if the set gripping force is the same, and some degree of variation may occur. For this reason, a value somewhat larger than the minimum non-slip gripping force (for example, 50 gf to 220 gf) may be set as the set gripping force. This prevents the actual gripping force from falling below the minimum non-slip gripping force due to variation. Furthermore, as shown in FIG. 3, a gripping force that is smaller than the minimum non-slip gripping force +500 gf can achieve cutting accuracy equivalent to that achieved when gripping is performed with the minimum non-slip gripping force. Therefore, it is preferable that the control unit 8 be configured to determine a value larger than the minimum non-slip gripping force obtained in the gripping force derivation process as the set gripping force.

[0050] As described above, in the optical fiber cutting method of this embodiment, the optical fiber F is gripped by a pair of gripping portions 10, 20 (steps S1, S2), and the pair of gripping portions 10, 20 are moved away from each other along the longitudinal direction X of the optical fiber F while changing the gripping force of at least one of the pair of gripping portions 10, 20 (steps S3, S4). The gripping force when the tension applied to the optical fiber F reaches a predetermined threshold is set as the minimum non-slip gripping force (steps S5 to S7). The optical fiber F is gripped by at least one of the pair of gripping portions 10, 20 with a set gripping force determined based on the minimum non-slip gripping force, and the blade 7 is applied to the glass portion f1 of the optical fiber F located between the pair of gripping portions 10, 20 to cut the optical fiber F.

[0051] The optical fiber cutting device 1 of this embodiment includes a pair of gripping sections 10, 20 that grip the optical fiber F, a gripping force applying section 14 that is provided on at least one of the pair of gripping sections 10, 20 and is capable of changing the gripping force, a tension applying section A that applies tension to the optical fiber F by separating the pair of gripping sections 10, 20 from each other along the longitudinal direction X of the optical fiber F, a tension measuring sensor 6 that measures the tension, a control section 8 that controls the gripping force generated by the gripping force applying section 14, and a pair of gripping sections 10, 20 that are provided in the longitudinal direction X. and a blade 7 that is located between the gripping parts 10, 20 and cuts the glass part f1 of the optical fiber F, and the control part 8 determines a set gripping force based on the minimum gripping force (minimum non-slip gripping force) that allows at least one of the pair of gripping parts 10, 20 to grip the optical fiber F without slipping when a predetermined tension is applied to the optical fiber F, and applies tension to the optical fiber F when at least one of the pair of gripping parts 10, 20 is gripping the optical fiber F with the set gripping force, and cuts the optical fiber F with the blade 7.

[0052] According to such an optical fiber cleaving method or optical fiber cleaving device 1, the optical fiber F is gripped with a set gripping force determined based on the minimum non-slip gripping force. As a result, when cleaving the optical fiber F, an excessively large gripping force on the optical fiber F is avoided, and an increase in the cut surface angle of the optical fiber F can be suppressed. It is also possible to suppress slippage of the optical fiber F caused by insufficient gripping force during cleaving. In the past, the magnitude of the gripping force was sometimes determined based on the experience and intuition of the worker. In contrast, by determining the set gripping force based on the minimum non-slip gripping force, as in the optical fiber cleaving device of the above embodiment, variation between workers in the cleaving operation can be suppressed, making it possible to cleave the optical fiber more stably and successfully.

[0053] Furthermore, the optical fiber cleaver 1 of this embodiment may be equipped with a storage unit that stores at least one of the minimum non-slip gripping force, the set gripping force, the control value for applying the minimum non-slip gripping force, and the control value for applying the set gripping force. In this case, the minimum non-slip gripping force, etc., can be read out and used for subsequent operations. It is believed that the minimum non-slip gripping force will be approximately the same for optical fibers F of the same type. In other words, if the minimum non-slip gripping force is measured once and the set gripping force is determined, the same set gripping force can be used to ensure an appropriate gripping force when cleaving optical fibers F of the same type thereafter. Therefore, the efficiency of repeated cleaving of optical fibers F can be improved.

[0054] Furthermore, in this embodiment, the optical fiber F is gripped so that slippage occurs in at least one of the pair of gripping portions 10, 20, and while increasing the gripping force of at least one of the pair of gripping portions 10, 20, the pair of gripping portions 10, 20 are moved away from each other along the longitudinal direction X of the optical fiber F, and the gripping force at which the tension applied to the optical fiber F reaches a predetermined threshold is defined as the minimum non-slip gripping force. With this configuration, when measuring the minimum non-slip gripping force, it is possible to prevent the coating f2 from being plastically deformed due to a large gripping force being applied. Furthermore, in an optical fiber F having a cavity in the glass portion f1, it is possible to prevent damage to the cavity portion due to excessive gripping force. Therefore, after measuring the minimum non-slip gripping force, the optical fiber F can be cut directly and the cut optical fiber F can be reused.

[0055] (Second embodiment) Next, a second embodiment of the present invention will be described, but the basic configuration is the same as that of the first embodiment. Therefore, the same components are given the same reference numerals and their description will be omitted, and only the differences will be described.

[0056] Fig. 4 is a flowchart showing the gripping force deriving step in the second embodiment. As shown in Fig. 4, in this embodiment, first, the optical fiber F is gripped by the second gripping part 20 (step S11). The gripping force at this time is set to a non-slip gripping force, similar to step S1 in the first embodiment. Next, the optical fiber F is gripped by the first gripping part 10 (step S12). The gripping force at this time is set to be a very small gripping force, similar to step S2 in the first embodiment.

[0057] Next, the control unit 8 drives the gripper movement actuator 3 to move the first gripper 10 in a direction (+X side) away from the second gripper 20 (step S13). This is also the same as step S3 in the first embodiment. Next, the control unit 8 determines whether a predetermined time has elapsed. Alternatively, the control unit 8 determines whether the gripper movement actuator 3 has been driven a predetermined amount (step S14). If the predetermined time has not elapsed, or if the gripper movement actuator 3 has not been driven a predetermined amount, step S14 is repeated (step S14: NO). If the predetermined time has elapsed, or if the gripper movement actuator 3 has been driven a predetermined amount, the process proceeds to step S15 (step S14: YES).

[0058] In step S15, the control unit 8 stops the gripper-moving actuator 3. Next, the control unit 8 determines whether the reading of the tension measuring sensor 6 has reached a predetermined threshold value (step S16). The "predetermined threshold value" is as described in step S5 of the first embodiment. If the reading of the tension measuring sensor 6 has not reached the predetermined threshold value (step S16: NO), the process proceeds to step S17.

[0059] In step S17, the control unit 8 controls the pressure applying actuator of the first gripping force applying unit 14 to increase the gripping force of the first gripping unit 10 by one step (step S17). The magnitude of this "step" can be set arbitrarily, but the smaller the "step," the more accurate the measurement of the minimum non-slip gripping force and the longer the measurement time for the minimum non-slip gripping force. For example, by setting the magnitude of this "step" within the range of 10 gf to 50 gf, it is possible to achieve both high measurement accuracy and long measurement time for the minimum non-slip gripping force.

[0060] After step S17, control unit 8 repeats steps S13 to S16 again. As a result, the gripping force of first gripping unit 10 increases stepwise, and the tension of optical fiber F measured by tension measuring sensor 6 also increases. In step S16, if the reading of tension measuring sensor 6 reaches the predetermined threshold value (step S16: YES), the process proceeds to step S18. In step S18, the control unit 8 stores the gripping force of the first gripping unit 10 at that time in the memory unit as the minimum non-slip gripping force. As in step S7 in the first embodiment, the memory unit may store the minimum non-slip gripping force itself, or may store a control value for applying the minimum non-slip gripping force. The memory unit may also store a set gripping force, or may store a control value for applying the set gripping force.

[0061] According to this embodiment, the determination in step S16 is performed with the gripper-moving actuator 3 stopped. Therefore, even if there is a large difference between the kinetic friction force and the static friction force acting between the first gripper 10 and the optical fiber F, the minimum non-slip gripping force can be measured with high accuracy.

[0062] (Third embodiment) Next, a third embodiment of the present invention will be described, but the basic configuration is the same as that of the first embodiment. Therefore, the same components are given the same reference numerals and their description will be omitted, and only the differences will be described. In the first and second embodiments, the first gripping portion 10 grips the coating f2, and the second gripping portion 20 grips the glass portion f1. In contrast, in this embodiment, as shown in Fig. 5, both the first gripping portion 10 and the second gripping portion 20 grip the coating f2. The coating f2 of the optical fiber F is removed in the portion between the first gripping portion 10 and the second gripping portion 20, exposing the glass portion f1.

[0063] As shown in Fig. 5, the optical fiber cutting device 1A of this embodiment has a second gripping force imparting unit 24. The second gripping force imparting unit 24 includes a pressing actuator (not shown) such as a motor, and a gear train that transmits the power of the pressing actuator to the second lid 22. Although a detailed description will be omitted, when the pressing actuator of the second gripping force imparting unit 24 is activated, the power is transmitted to the second lid 22 via the gear train, and a downward force is applied to the second lid 22. This force becomes the gripping force with which the second gripping unit 20 grips the optical fiber F. Note that the configuration of the second gripping force imparting unit 24 is not limited to the configuration of this embodiment and can be modified as appropriate as long as it can change the gripping force.

[0064] That is, the optical fiber cutting device 1A has a gripping force imparting unit composed of a first gripping force imparting unit 14 and a second gripping force imparting unit 24. In other words, the optical fiber cutting device 1A has a pair of gripping force imparting units. The first gripping force imparting unit 14 is configured to be able to change the gripping force of the first gripping unit 10, which is one of the pair of gripping units. The second gripping force imparting unit 24 is configured to be able to change the gripping force of the second gripping unit 20, which is the other of the pair of gripping units.

[0065] The control unit 8 of this embodiment can control the gripping force with which the second gripping unit 20 grips the optical fiber F by driving the pressure applying actuator of the second gripping force applying unit 24. When controlling the gripping force, the control unit 8 may, for example, calculate the gripping force by back-calculating from the drive amount of the pressure applying actuator. Alternatively, a pressure sensor may be provided in the second gripping unit 20, and feedback control may be performed based on the output from the pressure sensor.

[0066] That is, the control unit 8 can control the gripping force (first gripping force) generated by the first gripping force application unit 14 and the gripping force (second gripping force) generated by the second gripping force application unit 24. In particular, the control unit 8 can control the gripping force generated by the first gripping force application unit 14 and the gripping force generated by the second gripping force application unit 24 so that they are equal to each other.

[0067] Next, the gripping force deriving step in this embodiment will be described with reference to FIG. 6, in this embodiment, first, the optical fiber F is gripped by the first gripping portion 10 and the second gripping portion 20 (step S21). At this time, the gripping forces of the first gripping portion 10 and the second gripping portion 20 are equal to each other and are minute gripping forces, as in step S1 of the first embodiment.

[0068] Next, the control unit 8 drives the gripper movement actuator 3 to move the first gripper 10 in a direction (+X side) away from the second gripper 20 (step S22). At this point, the grippers 10, 20 grip the coating f2 with a small gripping force, and slippage occurs between the grippers 10, 20 and the coating f2. Therefore, no tension acts on the optical fiber F, or a small tension acts on the optical fiber F due to friction between the grippers 10, 20 and the coating f2. The tension on the optical fiber F is measured by the tension measurement sensor 6 at any time.

[0069] Next, while maintaining the gripping forces of the gripping units 10, 20 equal to each other, the control unit 8 drives the pressure applying actuators of the gripping force applying units 14, 24 so that the respective gripping forces gradually increase (step S23). As the gripping forces of the gripping units 10, 20 increase, the friction between the gripping units 10, 20 and the coating f2 increases, and the tension acting on the optical fiber F increases. In other words, the magnitude of the tension of the optical fiber F measured by the tension measuring sensor 6 increases. The increase in the gripping forces of the gripping units 10, 20 continues until it is stopped in step S25, which will be described later.

[0070] Next, the control unit 8 determines whether the tension (reading value) of the optical fiber F measured by the tension measuring sensor 6 has reached a predetermined threshold value (step S24). The "predetermined threshold value" is as described in step S5 of the first embodiment. If the tension of the optical fiber F measured by the tension measuring sensor 6 is smaller than the predetermined threshold value (step S24: NO), the control unit 8 repeatedly performs the determination in step S24. As time passes, the gripping force of the gripping units 10, 20 increases, and therefore the tension of the optical fiber F measured by the tension measuring sensor 6 also increases.

[0071] If the tension of the optical fiber F measured by the tension measuring sensor 6 reaches the predetermined threshold value (step S24: YES), the process proceeds to step S25. The magnitude of the gripping force by the gripping units 10, 20 at this time is the minimum non-slip gripping force. That is, the minimum non-slip gripping force is determined by moving the first gripping unit 10 and the second gripping unit 20 away from each other along the longitudinal direction of the optical fiber while changing the gripping force of the first gripping unit 10 and the gripping force of the second gripping unit 20. In particular, the gripping force of the first gripping unit 10 and the gripping force of the second gripping unit 20 are changed so that the gripping force of the first gripping unit 10 and the gripping force of the second gripping unit 20 become equal to each other.

[0072] In step S25, the control unit 8 stops the pressure applying actuators and the gripping unit movement actuator 3 of the gripping force applying units 14, 24 and maintains (holds) this state. This stops the movement of the first gripping unit 10 toward the +X side and the increase in the gripping forces of the gripping units 10, 20. Therefore, the increase in tension acting on the optical fiber F also stops.

[0073] Next, the control unit 8 stores the gripping force of the gripping units 10, 20 at that time in the memory unit as the minimum non-slip gripping force (step S26). As in step S7 in the first embodiment, the control unit 8 may store the minimum non-slip gripping force itself in the memory unit, or may store a control value for applying the minimum non-slip gripping force. The memory unit may also store a set gripping force, or may store a control value for applying the set gripping force.

[0074] According to this embodiment, it is possible to prevent plastic deformation of the coating f2 due to application of a large gripping force in both of the gripping portions 10 and 20. Therefore, after measuring the minimum non-slip gripping force, the optical fiber F can be cut directly, and both of the cut optical fibers F can be used.

[0075] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described, which has the same basic configuration as the third embodiment. Therefore, the same components are denoted by the same reference numerals, and the description thereof will be omitted, and only the differences will be described.

[0076] Fig. 7 is a flowchart showing the gripping force deriving step in the fourth embodiment. As shown in Fig. 7, in this embodiment, first, the optical fiber F is gripped by the first gripping unit 10 and the second gripping unit 20 (step S31). At this time, as in step S21 in the third embodiment, the gripping forces of the first gripping unit 10 and the second gripping unit 20 are set to be equal and minute.

[0077] Next, the control unit 8 drives the gripper movement actuator 3 to move the first gripper 10 in a direction (+X side) away from the second gripper 20 (step S32). This is also the same as step S22 in the third embodiment. Next, the control unit 8 determines whether a predetermined time has elapsed. Alternatively, the control unit 8 determines whether the gripper movement actuator 3 has been driven a predetermined amount (step S33). If the predetermined time has not elapsed, or if the gripper movement actuator 3 has not been driven a predetermined amount, step S33 is repeated (step S33: NO). If the predetermined time has elapsed, or if the gripper movement actuator 3 has been driven a predetermined amount, the process proceeds to step S34 (step S33: YES).

[0078] In step S34, the control unit 8 stops the gripper-moving actuator 3. Next, the control unit 8 determines whether the reading of the tension measuring sensor 6 has reached a predetermined threshold value (step S35). The "predetermined threshold value" is as described in step S5 of the first embodiment. If the reading of the tension measuring sensor 6 has not reached the predetermined threshold value (step S35: NO), the process proceeds to step S36.

[0079] In step S36, the control unit 8 controls the pressure applying actuators of the gripping force applying units 14 and 24 to increase the gripping forces of the gripping units 10 and 20 by one step while maintaining the gripping forces of the gripping units 10 and 20 equal to each other (step S36). The magnitude of this "one step" is the same as in step S17 in the second embodiment.

[0080] After step S36, the control unit 8 repeats steps S32 to S35 again. As a result, the gripping force of the gripping units 10, 20 increases stepwise, and the tension of the optical fiber F measured by the tension measuring sensor 6 also increases. In step S35, if the reading of the tension measuring sensor 6 reaches the predetermined threshold value (step S35: YES), the process proceeds to step S37. In step S37, the control unit 8 stores the gripping force of the gripping units 10, 20 at that time in the memory unit as the minimum non-slip gripping force. As in step S7 in the first embodiment, the memory unit may store the minimum non-slip gripping force itself, or may store a control value for applying the minimum non-slip gripping force. The memory unit may also store a set gripping force, or may store a control value for applying the set gripping force.

[0081] According to this embodiment, the determination in step S35 is performed with the gripper-moving actuator 3 stopped. Therefore, even if there is a large difference between the kinetic friction force and the static friction force acting between the grippers 10, 20 and the optical fiber F, the minimum non-slip gripping force can be measured with high accuracy.

[0082] (Fifth embodiment) Next, a fifth embodiment of the present invention will be described, which has the same basic configuration as the first embodiment. Therefore, the same components are denoted by the same reference numerals, and the description thereof will be omitted, and only the differences will be described. In the first to fourth embodiments, the gripping force by at least the first gripping unit 10 is increased from a small gripping force as a starting point, and the gripping force when the tension of the optical fiber F reaches a predetermined threshold is defined as the minimum non-slip gripping force. In contrast, in this embodiment, the gripping force by the first gripping unit 10 is decreased from a non-slip gripping force as a starting point, and the gripping force when the tension of the optical fiber F falls below the predetermined threshold is defined as the minimum non-slip gripping force. This will be explained in more detail below using FIG. 8.

[0083] 8, in this embodiment, first, the optical fiber F is gripped by the second gripping portion 20 (step S41). The gripping force at this time is the same as the non-slip gripping force in the first embodiment. Next, the optical fiber F is gripped by the first gripping unit 10 (step S42). The gripping force at this time is set to a non-slip gripping force by the control unit 8 controlling the pressure applying actuator of the first gripping force applying unit 14. Note that the gripping forces of the first gripping unit 10 and the second gripping unit 20 may be different as long as the gripping force is such that slippage does not occur in either the first gripping unit 10 or the second gripping unit 20 even when a predetermined tension is applied to the optical fiber F.

[0084] Next, the control unit 8 drives the gripper movement actuator 3 to move the first gripper 10 in a direction (+X side) away from the second gripper 20 (step S43). At this time, since both the first gripper 10 and the second gripper 20 grip the optical fiber F with a non-slip gripping force, tension is quickly applied to the optical fiber F as long as there is no slack in the optical fiber F.

[0085] Next, the control unit 8 determines whether the tension (reading value) of the optical fiber F measured by the tension measuring sensor 6 has reached a predetermined threshold value (step S44). The "predetermined threshold value" is as described in step S5 of the first embodiment. If the reading value of the tension measuring sensor 6 has not reached the predetermined threshold value (step S44: NO), step S44 is repeated. During this time, the first gripping unit 10 is moved toward the +X side by the driving of the gripping unit movement actuator 3, so that the slack in the optical fiber F is eventually eliminated and tension in the optical fiber F is applied.

[0086] If the tension of the optical fiber F measured by the tension measuring sensor 6 reaches the predetermined threshold value (step S44: YES), the process proceeds to step S45. In step S45, the control unit 8 stops driving the gripper movement actuator 3 and maintains (holds) this state, so that the first gripper 10 remains stationary and a predetermined tension is applied to the optical fiber F. Next, the control unit 8 drives the pressure applying actuator of the first gripping force applying unit 14 so as to gradually reduce the gripping force of the first gripping unit 10 on the coating f2 (step S46). When the gripping force of the first gripping unit 10 is reduced, the frictional force between the first gripping unit 10 and the coating f2 gradually decreases.

[0087] Next, the control unit 8 determines whether the reading of the tension measuring sensor 6 has fallen below a predetermined threshold (step S47). If the tension of the optical fiber F measured by the tension measuring sensor 6 is greater than the predetermined threshold (step S47: NO), the control unit 8 repeatedly makes the determination in step S47. As time passes, the gripping force of the first gripping unit 10 decreases, and eventually the frictional force between the first gripping unit 10 and the coating f2 falls below the tension of the optical fiber F. At this time, slippage occurs between the first gripping unit 10 and the coating f2, and the tension of the optical fiber F decreases. When the tension of the optical fiber F measured by the tension measuring sensor 6 falls below the predetermined threshold (step S47: YES), the control unit 8 proceeds to step S48.

[0088] In step S48, the control unit 8 stops driving the pressure applying actuator of the first gripping force applying unit 14. Next, the control unit 8 stores the gripping force of the first gripping unit 10 at that time in the memory unit as the minimum non-slip gripping force (step S49). As in step S7 in the first embodiment, the memory unit may store the minimum non-slip gripping force itself, or may store a control value for applying the minimum non-slip gripping force. The memory unit may also store a set gripping force, or may store a control value for applying the set gripping force.

[0089] As described above, in this embodiment, the optical fiber F is gripped by the pair of gripping units 10, 20 to prevent slippage, and the pair of gripping units 10, 20 are moved away from each other along the longitudinal direction of the optical fiber F while reducing the gripping force of at least one of the pair of gripping units 10, 20. The gripping force at which slippage occurs between the gripping units 10, 20 and the optical fiber F after the reduced gripping force is defined as the minimum non-slip gripping force. With this configuration, the stroke required to move the gripping units 10, 20 away from each other can be reduced when measuring the minimum non-slip gripping force. More specifically, once the slack in the optical fiber F between the first gripping unit 10 and the second gripping unit 20 is eliminated and tension is applied to the optical fiber F, there is no need to move the gripping units 10, 20 any further. Therefore, the size of the optical fiber cleaver 1 in the longitudinal direction X can be reduced, and the time required to measure the minimum non-slip gripping force can also be shortened.

[0090] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0091] For example, in the first to fifth embodiments, only the first gripping portion 10 of the pair of gripping portions 10, 20 moves, but a configuration in which the second gripping portion 20 moves toward the -X side may be adopted. Also, other configurations may be adopted as long as the distance between the first gripping portion 10 and the second gripping portion 20 can be changed. Furthermore, in the gripping force derivation process in the first to fifth embodiments, the derived minimum non-slip gripping force and the like are stored in a memory unit (steps S7, S18, S26, S37, S49). However, it is not essential that the memory unit store the minimum non-slip gripping force and the like. For example, the operator may record and use the minimum non-slip gripping force and the like. Therefore, the optical fiber cutting device 1, 1A does not need to have a memory unit. Also, instead of using the blade 7, a laser may be irradiated onto the glass portion f1 to scratch it.

[0092] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention, and the above-described embodiments and variations may be combined as appropriate. [Explanation of symbols]

[0093] 1, 1A... Optical fiber cutting device 6... Tension measurement sensor 7... Blade 8... Control unit 10, 20... Gripping unit 14... Gripping force applying unit A... Tension applying unit F... Optical fiber f1... Glass unit

Claims

1. a pair of gripping parts for gripping an optical fiber having an exposed glass part; a gripping force applying portion provided on at least one of the pair of gripping portions and capable of changing the gripping force; a tension applying unit that applies tension to the optical fiber by moving the pair of gripping units apart from each other along the longitudinal direction of the optical fiber; a tension measurement sensor for measuring the tension; a control unit that controls the gripping force generated by the gripping force applying unit; a blade positioned between the pair of gripping portions in the longitudinal direction and configured to incision the exposed glass portion of the optical fiber, the control unit determines a set gripping force based on a minimum non-slip gripping force, which is the minimum gripping force at which at least one of the pair of gripping units can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber; applying tension to the optical fiber while at least one of the pair of gripping portions grips the optical fiber with the set gripping force, and cutting the optical fiber by scratching it with the blade; the pair of gripping portions includes a first gripping portion and a second gripping portion, an optical fiber cutting device, wherein the control unit holds the optical fiber so that slippage does not occur with the first gripping unit, moves the first gripping unit and the second gripping unit away from each other along the longitudinal direction while reducing the gripping force of the first gripping unit, and sets the gripping force when slippage occurs between the first gripping unit and the optical fiber to the minimum non-slip gripping force.

2. A pair of gripping parts for gripping an optical fiber having an exposed glass part; a gripping force applying portion provided on at least one of the pair of gripping portions and capable of changing the gripping force; a tension applying unit that applies tension to the optical fiber by moving the pair of gripping units apart from each other along the longitudinal direction of the optical fiber using a gripping unit moving actuator; a tension measurement sensor for measuring the tension; a control unit that controls the gripping force generated by the gripping force applying unit; a blade positioned between the pair of gripping portions in the longitudinal direction and configured to incision the exposed glass portion of the optical fiber; a storage unit, the control unit separates the pair of grippers using the gripper movement actuator while increasing the gripping force from a minute gripping force, and determines whether a predetermined time has elapsed or whether the gripper movement actuator has been driven by a predetermined amount; When a predetermined time has elapsed or when the gripper moving actuator has been driven by a predetermined amount, the control unit stops the gripper moving actuator and determines whether or not the reading of the tension measuring sensor has reached a predetermined threshold value; When the reading value of the tension measuring sensor reaches the threshold value, the control unit stores the gripping force of at least one of the gripping units at that time in the memory unit as a minimum non-slip gripping force, which is the minimum gripping force that can grip the optical fiber without slipping, and determines a set gripping force based on the minimum non-slip gripping force; an optical fiber cutting device that applies tension to the optical fiber while at least one of the pair of gripping parts grips the optical fiber with the set gripping force, and cuts the optical fiber by damaging it with the blade.

3. The gripping force applying unit is a first gripping force applying unit capable of changing the gripping force of one of the pair of gripping units; a second gripping force applying portion capable of changing the gripping force of the other of the pair of gripping portions, The control unit controls the gripping force generated by the first gripping force application unit and the gripping force generated by the second gripping force application unit.

3. The optical fiber cutting device according to claim 1 or 2.

4. The control unit controls the gripping force generated by the first gripping force application unit and the gripping force generated by the second gripping force application unit so that they are equal to each other.

4. The optical fiber cutting device according to claim 3.

5. The gripping force applying unit is a first gripping force applying unit including a pressure applying actuator capable of changing the gripping force of one of the pair of gripping units; a second gripping force applying portion capable of changing the gripping force of the other of the pair of gripping portions, When the reading value of the tension measuring sensor does not reach the threshold value, the control unit controls the pressure applying actuator of the first gripping force applying unit to increase the gripping force of one of the pair of gripping units by one level, and then the control unit determines whether a predetermined time has elapsed or whether the gripper moving actuator has been driven by a predetermined amount; 3. The optical fiber cutting device according to claim 2, wherein when a predetermined time has elapsed or when the gripper movement actuator has been driven a predetermined amount, the control unit stops the gripper movement actuator and determines whether the reading of the tension measuring sensor has reached the threshold value.

6. The optical fiber having the exposed glass portion is held by the first holding portion and the second holding portion; a minimum non-slip gripping force, which is the minimum gripping force at which the first gripping part can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber, by moving the first gripping part and the second gripping part away from each other along the longitudinal direction of the optical fiber while reducing the gripping force of the first gripping part from a non-slip gripping force at which no slippage occurs between the optical fiber and the first gripping part; an optical fiber cutting method, wherein the first gripping unit grips the optical fiber with a set gripping force determined based on the minimum non-slip gripping force, applies tension to the optical fiber, and cuts the optical fiber by applying a blade to a portion of the optical fiber where the glass portion is exposed and located between the first gripping unit and the second gripping unit.

7. 7. The optical fiber cutting method according to claim 6, wherein the gripping force of the first gripping portion and the gripping force of the second gripping portion are changed so that the gripping force of the first gripping portion and the gripping force of the second gripping portion are equal to each other.

8. An optical fiber having an exposed glass portion is gripped by a first gripping portion and a second gripping portion, While increasing the gripping force of the first gripping part from a minute gripping force, a step of moving the first gripping portion and the second gripping portion apart from each other along the longitudinal direction of the optical fiber by a gripping portion moving actuator; a step of determining whether a predetermined time has elapsed or whether the gripper moving actuator has been driven a predetermined amount; and When a predetermined time has elapsed or when the gripper moving actuator has been driven by a predetermined amount, the gripper moving actuator is stopped, and a step of determining whether or not the reading of the tension measuring sensor has reached a predetermined threshold is performed; When the reading of the tension measuring sensor reaches the threshold value, the gripping force at that time is determined as a minimum non-slip gripping force, which is the minimum gripping force with which the first gripping part can grip the optical fiber without slipping when a predetermined tension is applied to the optical fiber, an optical fiber cutting method, wherein the first gripping unit grips the optical fiber with a set gripping force determined based on the minimum non-slip gripping force, applies tension to the optical fiber, and cuts the optical fiber by applying a blade to a portion of the optical fiber where the glass portion is exposed and located between the first gripping unit and the second gripping unit.

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