Optical fiber preform manufacturing apparatus and method

Abstract

To provide a manufacturing apparatus and a manufacturing method of an optical fiber preform, capable of adjusting freely the position of a burner, while securing airtightness in a reaction vessel.SOLUTION: A manufacturing apparatus of an optical fiber preform includes a reaction vessel in which a starting base material is arranged, a burner inserted from an opening of the reaction vessel, for spraying glass soot to the starting base material in the reaction vessel, and a seal member having an internal space for storing the burner, stretchable according to the position of the burner, and connecting airtightly the opening to the internal space.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for manufacturing an optical fiber preform. [Background technology]

[0002] Patent Document 1 discloses a VAD apparatus for manufacturing an optical fiber preform by depositing glass soot ejected from a burner onto the outer periphery of a starting substrate in a reaction vessel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-9142 A Summary of the Invention [Problem to be solved by the invention]

[0004] If there is a gap between the burner and the reaction vessel in the VAD device, foreign matter in the outside air may be drawn into the reaction vessel through the gap and become mixed into the glass soot. If a sintering process is performed to create an optical fiber preform in this state, air bubbles will be generated from the foreign matter, which may cause the optical fiber to break when the preform is drawn into optical fiber. In addition, as the deposition of the glass soot progresses, the distance between the burner and the optical fiber preform becomes narrower. However, if the distance between the burner and the optical fiber preform changes, the quality of the deposited glass soot also changes, which is a problem. To address these problems, the device in Patent Document 1 has a structure that ensures airtightness while allowing the position of the burner to be adjusted by filling the gap between the reaction vessel and the burner with a V-shaped seal member. However, in this device, in order to move the burner, it is necessary to insert or remove the burner between the seal members or tilt the burner, and there is a risk that a small gap will be generated in the seal member and the airtightness will be reduced.

[0005] In view of the above problems, an object of the present invention is to provide an apparatus and method for manufacturing an optical fiber preform, which can freely adjust the position of a burner while ensuring airtightness inside a reaction vessel. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a method for manufacturing a glass substrate, comprising: a reaction vessel in which a starting substrate is placed; a burner that is inserted from an opening of the reaction vessel and sprays glass soot onto the starting substrate within the reaction vessel; and a seal member that has an internal space for accommodating the burner, is expandable and contractable according to a position of the burner, and airtightly connects the opening and the internal space. The seal member includes at least a first connecting portion that connects to the opening and a second connecting portion that connects to the burner. The present invention provides an apparatus for manufacturing an optical fiber preform.

[0007] According to another aspect of the present invention, a method for producing a glass substrate includes the steps of: arranging a starting substrate in a reaction vessel; airtightly connecting an opening of the reaction vessel to the internal space by a seal member having an internal space for accommodating a burner and capable of expanding and contracting according to a position of the burner; spraying glass soot from the burner inserted from the opening onto the starting substrate; and adjusting the position of the burner. The seal member includes at least a first connecting portion that connects to the opening and a second connecting portion that connects to the burner. The present invention provides a method for producing an optical fiber preform. Effect of the Invention

[0008] According to the present invention, there is provided an apparatus and method for manufacturing an optical fiber preform, which can freely adjust the position of a burner while ensuring airtightness inside a reaction vessel. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an overall configuration of a manufacturing apparatus according to a first embodiment. [Diagram 2] 3 is an enlarged cross-sectional view showing a support structure and a seal structure for a burner in the manufacturing apparatus according to the first embodiment. FIG. [Diagram 3] 2 is a block diagram showing a schematic configuration of a control system of the manufacturing apparatus according to the first embodiment. FIG. [Figure 4] 4 is a flowchart showing an example of a process during glass soot formation in the manufacturing apparatus according to the first embodiment. [Diagram 5] 4 is a schematic cross-sectional view showing a state of a burner before position / angle adjustment in the manufacturing apparatus according to the first embodiment. FIG. [Figure 6] 3 is a schematic cross-sectional view showing a state in which an optical fiber preform is pulled up in the manufacturing apparatus according to the first embodiment. FIG. [Figure 7] 10 is a flowchart showing an example of a process during glass soot formation in a manufacturing apparatus according to a second embodiment. [Figure 8] 13 is a flowchart showing an example of a process during glass soot formation in a manufacturing apparatus according to a third embodiment. [Figure 9] 13 is a flowchart showing an example of a process during glass soot formation in a manufacturing apparatus according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings described below, parts having the same functions are designated by the same reference numerals, and repeated description thereof will be omitted.

[0011] [First embodiment] Fig. 1 is a schematic cross-sectional view showing the overall configuration of a manufacturing apparatus 100 according to this embodiment. Fig. 2 is an enlarged cross-sectional view showing a support structure and a seal structure of a burner 103 in the manufacturing apparatus 100 according to this embodiment.

[0012] As shown in FIG. 1, the manufacturing apparatus 100 includes a reaction vessel 101, a burner 103 arranged to protrude into the reaction vessel 101 from an opening 102 provided in an inclined surface spanning the side wall 101a on the air supply side and the bottom 101d of the reaction vessel 101, and an exhaust mechanism 104 provided via an exhaust port 104a provided in a side wall 101b (side wall 101b on the exhaust side) opposite the side wall 101a.

[0013] The exhaust mechanism 104 has a pump and a valve 104b (not shown), and by driving the pump in accordance with instructions from the control unit 200 (described later), a flow of gas (exhaust gas G2) is formed from the intake side (opening 102) of the reaction vessel 101 to the exhaust side (exhaust port 104a), thereby enabling the inside of the reaction vessel 101 to be exhausted.

[0014] The manufacturing apparatus 100 also includes a rotation and elevation mechanism 106 on the ceiling 101c side of the reaction vessel 101. The rotation and elevation mechanism 106 is connected to a target rod 107 serving as a starting substrate. The rotation and elevation mechanism 106 rotates the target rod 107 in a rotation direction R with the longitudinal direction of the target rod 107 as the rotation axis in accordance with an instruction from a control unit 200, which will be described later. Furthermore, the rotation and elevation mechanism 106 drives the target rod 107 in the vertical direction in accordance with an instruction from the control unit 200, thereby raising and lowering the optical fiber preform 10.

[0015] The burner 103 is supplied with a combustion gas from a combustion gas supplying device 114a via a combustion gas supplying line 114b, and is supplied with a glass frit gas (a gas that becomes glass particles by hydrolysis due to combustion) from a glass frit gas supplying device 114c via a glass frit gas supplying line 114d.

[0016] The combustion gas supply device 114a supplies combustion gas, the flow rate of which is independently controlled according to instructions from a control unit 200 described below, to the burner 103. The combustion gas contains, for example, at least one of hydrogen (H2) and oxygen (O2).

[0017] The glass raw material gas supply device 114c supplies a flow-controlled glass raw material gas (eg, SiCl4) to the burner 103 as a raw material for synthesizing an optical fiber preform, according to an instruction from a control unit 200 described later.

[0018] The burner 103, in accordance with instructions from a control unit 200 described later, forms a flame using a combustion gas supplied from a combustion gas supply device 114a, hydrolyzes a glass raw material gas supplied from a glass raw material gas supply device 114c in the flame to form glass soot, and blows the flame (gas G1) containing glass particles onto a target rod 107 to deposit the glass particles and form an optical fiber preform 10.

[0019] The optical fiber preform (glass soot preform) 10 manufactured by the manufacturing apparatus 100 is formed on the outer periphery of a target rod 107 as a starting substrate, and is composed of an inner deposition soot 10a formed on the inside and an outer deposition soot 10b formed on the outside of the inner deposition soot 10a. The inner deposition soot 10a corresponds to the core of the optical fiber, which is the final product. On the other hand, the outer deposition soot 10b corresponds to the cladding of the optical fiber.

[0020] As shown in Figs. 1 and 2, the burner 103 is disposed such that one end thereof protrudes from the opening 102 toward the inside of the reaction vessel 101. The other end of the burner 103 is supported in a state where it is gripped by a gripping portion 112a of a burner support member 112. The gripping portion 112a is connected to a plate-shaped first fixing member 112b at an end opposite to the gripping position of the burner 103. The first fixing member 112b is connected to a plate-shaped second fixing member 112d by a fastening metal fitting 112c. The second fixing member 112d is placed on the inclined surface 113a of the base 113 in parallel with the surface direction of the inclined surface 113a.

[0021] A burner position adjustment device 115 capable of adjusting the position and angle of the burner 103 by driving the burner support member 112 and the inclined surface 113a of the pedestal 113 is installed inside the pedestal 113. The inclined surface 113a of the pedestal 113 is composed of a plate-like member that can be driven about an axis Q independently of the main body of the pedestal 113.

[0022] In this embodiment, the burner position adjustment device 115 drives the burner support member 112 in a direction along the inclined surface 113a (direction A in the figure), whereby the burner 103 moves so that the gas discharge port is located at a predetermined position.

[0023] Moreover, the burner position adjustment device 115 rotates the plate-like member constituting the inclined surface 113a of the pedestal 113 about the axis Q, thereby driving the burner support member 112 placed on the inclined surface 113a. This adjusts the angle between the axial direction (vertical downward direction) of the target rod 107 and the axial direction of the burner 103. Note that the method of adjusting the distance and angle of the burner position adjustment device 115 in this embodiment is merely an example and is not limited to this. For example, instead of rotating the inclined surface 113a of the pedestal 113 about the axis Q, the burner support member 112 may be structured to rise and fall as a whole in the Y direction.

[0024] The burner 103 is inserted into the internal space of a seal member 108 which is formed into a generally cylindrical shape. The seal member 108 is made of a material which is heat-resistant, airtight and stretchable. The material of the seal member 108 is, for example, a synthetic resin, but is not limited to this.

[0025] In this embodiment, both ends of the seal member 108 are formed into a flange shape. One end of the seal member 108 is connected to the peripheral region of the opening 102 of the reaction vessel 101 by using a flange 110 and a fixing screw 111 with a heat-resistant packing 109 sandwiched therebetween.

[0026] Similarly, the other end of the seal member 108 is connected to a gripping portion 112a of a burner support member 112 by using a flange 110 and a fixing screw 111 with a heat-resistant packing 109 sandwiched between them. As a result, an airtight internal space Z is formed in the seal member 108 around the burner 103.

[0027] In this embodiment, the main body of the seal member 108 is formed in a bellows shape in the longitudinal direction. This allows the seal member 108 to freely deform while maintaining the airtightness of the internal space Z of the seal member 108 and the inside of the reaction vessel 101 even if the burner 103 and the burner support member 112 are driven in the A direction or the Y direction.

[0028] Furthermore, in this embodiment, the manufacturing apparatus 100 includes a tip detection sensor 105. The tip detection sensor 105 detects the tip position of the optical fiber preform 10 in the reaction vessel 101. The tip detection sensor 105 includes a laser emitter 105a and a laser receiver 105b. The laser emitter 105a irradiates a laser toward the laser receiver 105b disposed facing the opposite side wall 101b in the reaction vessel 101 in accordance with an instruction from the control unit 200. The laser receiver 105b receives the laser irradiated from the laser emitter 105a.

[0029] When glass soot accumulates on the surface of the optical fiber preform 10 to a certain extent, the laser irradiated from the laser emitter 105a hits the tip of the optical fiber preform 10 and is blocked. In such a case, the laser receiver 105b cannot receive the laser, and the tip detection sensor 105 outputs a detection signal of the tip position of the optical fiber preform 10. Conversely, when the laser irradiated from the laser emitter 105a reaches the laser receiver 105b on the opposite side without hitting the tip of the optical fiber preform 10, i.e., an obstacle, the tip detection sensor 105 does not output a detection signal of the tip position of the optical fiber preform 10.

[0030] 3 is a block diagram showing a schematic configuration of a control system according to this embodiment. The control unit 200 has a CPU (Central Processing Unit) 201 that executes various processing operations such as calculations, controls, and determinations, and a ROM (Read Only Memory) 202 that stores various control programs executed by the CPU 201. The control unit 200 further has a RAM (Random Access Memory) 203 that temporarily stores data during processing operations of the CPU 201, input data, and the like, and a non-volatile memory 204 such as an HDD (Hard Disk Drive) or SSD (Solid State Drive).

[0031] In addition, the control unit 200 is connected to an input operation unit 205 including a keyboard or various switches for inputting predetermined commands or data, and a display unit 206 (e.g., a liquid crystal display or an organic EL display) for displaying various information including the input / setting status of the manufacturing equipment 100.

[0032] The control unit 200 is connected to the rotary lifting mechanism 106, the burner 103, the combustion gas supply device 114a, the glass raw material gas supply device 114c, the exhaust mechanism 104, the burner position adjustment device 115, and the tip detection sensor 105 via drive circuits 207a to 207g, respectively.

[0033] Hereinafter, the operation of the manufacturing apparatus 100 configured as described above will be described with reference to the drawings.

[0034] 4 is a flow chart showing an example of a process for forming glass soot in the manufacturing apparatus 100 according to the present embodiment. Note that this process is only an example and can be arbitrarily changed.

[0035] First, the control unit 200 acquires the lot information of the optical fiber preform 10 to be manufactured, which is inputted from the input operation unit 205 (step S101).

[0036] Next, the control unit 200 controls the rotary lift mechanism 106 to place the optical fiber preform 10 at a predetermined position in the reaction vessel 101 (step S102). For example, the control unit 200 causes the rotary lift mechanism 106 to carry the optical fiber preform 10 into the reaction vessel 101 from an upper opening (not shown) and to move it down inside the vessel, and detects the tip position of the optical fiber preform 10 with the tip detection sensor 105. Then, the control unit 200 causes the rotary lift mechanism 106 to move the optical fiber preform 10 a predetermined height and stop it at that position.

[0037] 5 is a schematic cross-sectional view showing the state of the burner 103 before the position and angle are adjusted in the manufacturing apparatus 100 according to this embodiment. Here, the tip of the optical fiber preform 10 is disposed at a height that is not detected by the tip detection sensor 105. However, the direction of the gas discharge port of the burner 103 is inclined downward from the tip position of the optical fiber preform 10. In such a case, the position and angle of the burner 103 need to be adjusted.

[0038] Next, the control unit 200 refers to the manufacturing conditions stored in the ROM 202 or RAM 203 based on the lot information, and determines the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 at the start of the glass soot formation process (step S103).

[0039] Next, the control unit 200 controls the burner position adjustment device 115 based on the information on the positional relationship and the angle of the burner 103 determined in step S103, and adjusts the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 (step S104).

[0040] The above-mentioned Fig. 1 shows a state after the position and angle of the burner 103 are adjusted from the state shown in Fig. 5. In Fig. 1, compared with the state in Fig. 5, the burner support member 112 is driven along the inclined surface 113a of the base 113 so that the gas discharge port of the burner 103 is located at a predetermined position.

[0041] At the same time, the burner position adjustment device 115 changes the inclination angle of the inclined surface 113a of the pedestal 113 by a driving mechanism (not shown). Since the burner support member 112 and the burner 103 installed on the inclined surface 113a move, the angle of gas emission of the burner 103 with respect to the optical fiber preform 10 and the target rod 107 is adjusted. For example, in FIG. 1, the inclination angle of the inclined surface 113a of the pedestal 113 is finely adjusted from angle θ2 to angle θ1, as compared with the state in FIG. 5. As a result, the inclination angle of the burner 103 is changed so that gas is supplied to a desired position on the optical fiber preform 10.

[0042] Next, the control unit 200 starts the glass soot forming process (step S105). In the glass soot forming process, the control unit 200 controls the rotary lift mechanism 106 to rotate the target rod 107 in a rotation direction R with the longitudinal direction of the target rod 107 as the rotation axis.

[0043] In addition, in the glass soot forming process, the control unit 200 controls the combustion gas supply device 114a to form a flame with the combustion gas, and controls the glass raw material gas supply device 114c to hydrolyze the glass raw material gas in the flame to form glass particles, and blows the flame containing the glass particles against the target rod 107.

[0044] Next, the control unit 200 determines whether the optical fiber preform 10 has reached a predetermined pulled length (step S106). If the control unit 200 determines that the optical fiber preform 10 has reached the predetermined pulled length (step S106: YES), the process proceeds to step S107. At this time, the control unit 200 controls the rotating / lifting mechanism 106 to lift the optical fiber preform 10 to a predetermined position.

[0045] On the other hand, when the control unit 200 determines that the optical fiber preform 10 has not reached the predetermined pulled length (step S106: NO), the control unit 200 continues the glass soot forming process under the same conditions.

[0046] In step S107, the control unit 200 detects that the optical fiber preform 10 has reached the final pulling length. At this time, the control unit 200 controls the rotating and lifting mechanism 106 to pull up the optical fiber preform 10. As a result, even if the formation of glass soot progresses on the surface of the optical fiber preform 10 and the length of the optical fiber preform 10 in the vertical direction extends, the optical fiber preform 10 in the reaction vessel 101 can be pulled up at the timing when it reaches the desired pulling length.

[0047] Fig. 6 is a schematic cross-sectional view showing a state in which the optical fiber preform 10 is pulled up in the manufacturing apparatus 100 according to the present embodiment. Fig. 6 shows a state in which, when the tip detection sensor 105 detects the tip (lowest end) of the optical fiber preform 10 as glass soot accumulates on the surface of the optical fiber preform 10, the optical fiber preform 10 is pulled up in the vertical direction V together with the target rod 107 by the rotary lifting mechanism 106. As a result, the distance between the tip of the optical fiber preform 10 and the gas outlet of the burner 103 is maintained at d.

[0048] In step S108, the control unit 200 ends the glass soot forming process and ends the process. Specifically, the control unit 200 controls the combustion gas supply device 114a and the glass raw material gas supply device 114c to stop the gas supply. The control unit 200 also controls the rotary lift mechanism 106 to stop the rotation of the target rod 107. Then, the control unit 200 drives the target rod 107 to carry out the optical fiber preform 10 having the glass soot deposited on its surface from the reaction vessel 101.

[0049] As described above, the manufacturing apparatus 100 according to this embodiment is provided with the seal member 108 that can freely expand and contract according to the position and angle of the burner 103, and therefore it is possible to solve the problems of ensuring airtightness and troublesome position adjustment of the burner 103. That is, it is possible to prevent foreign matter from entering the optical fiber preform 10, and as a result, it is possible to avoid defects such as breakage when drawing the optical fiber, and therefore it is possible to manufacture an optical fiber with a good refractive index distribution.

[0050] In the manufacturing apparatus 100 according to this embodiment, the seal member 108 includes at least a first connecting portion that connects to the opening 102 of the reaction vessel 101 and a second connecting portion that connects to the burner 103. This allows the burner 103 to be reliably connected to the reaction vessel 101 while maintaining the airtightness of the manufacturing apparatus 100.

[0051] Furthermore, the opening 102 of the reaction vessel 101 and the seal member 108 are airtightly connected via a heat-resistant packing 109. This makes it possible to suppress thermal deformation even when the inside of the reaction vessel becomes hot, thereby maintaining airtightness.

[0052] The manufacturing apparatus 100 further includes a burner support member 112 that supports the burner 103 outside the reaction vessel 101, and a burner position adjustment device (adjustment mechanism) 115 that adjusts the distance from the burner 103 to the target rod (starting substrate) 107 and the angle between the burner 103 and the target rod 107. This allows the distance and angle of the burner 103 to be easily adjusted.

[0053] Moreover, the burner position adjustment device 115 adjusts the position and angle of the burner 103 by driving the burner support member 112. This makes it possible to easily adjust the distance and angle of the burner 103 via the burner support member 112.

[0054] In addition, the burner position adjustment device 115 adjusts the position and angle of the burner 103 based on lot information of the optical fiber preform 10 to be manufactured. This makes it possible to blow glass soot onto the target rod 107 under optimal conditions for each lot.

[0055] In addition, the manufacturing apparatus 100 further includes a base 113 having an inclined surface 113a on which the burner support member 112 is placed, and the burner position adjustment device 115 can adjust the distance from the gas outlet of the burner 103 to the target rod 107 by driving the burner support member 112 along the inclined surface 113a.

[0056] In addition, the burner position adjustment device 115 can adjust the angle of the burner 103 with respect to the target rod 107, that is, the angle at which the reactive gas is sprayed, by changing the inclination angle of the inclined surface 113a. This allows the position and angle of the burner 103 to be adjusted accurately and easily.

[0057] Furthermore, since the seal member 108 is formed in a bellows shape in the longitudinal direction, it can easily expand and contract, thereby allowing the position and angle of the burner 103 to be repeatedly adjusted.

[0058] The manufacturing apparatus 100 described in the above embodiment can also be configured as in the following second to fourth embodiments. Note that the same reference numerals as those in the first embodiment indicate the same objects. Explanations of the parts common to the first embodiment will be omitted, and differences will be explained in detail.

[0059] [Second embodiment] This embodiment differs from the first embodiment in that it further includes a function for adjusting the position and angle of the burner 103 even during the glass soot forming process.

[0060] Fig. 7 is a flowchart showing an example of a process for forming glass soot in the manufacturing apparatus 100 according to the present embodiment. Fig. 7 differs only in part from Fig. 4 described in the first embodiment. In the following, a description of the common processes will be omitted, and differences will be described in detail.

[0061] First, the control unit 200 performs the processes of steps S101 to S106 in the same manner as in FIG. 4, and then the process proceeds to step S201.

[0062] In step S201, the control unit 200 refers to the manufacturing conditions stored in the ROM 202 or the RAM 203 based on the elapsed time from the start time of the glass soot formation process and the size of the optical fiber preform 10 estimated from the elapsed time, and determines the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103.

[0063] Next, the control unit 200 controls the burner position adjustment device 115 based on the information on the positional relationship and angle determined in step S201, and adjusts the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 (step S202).

[0064] Next, the control unit 200 determines whether or not adjustment instruction information regarding the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 has been input (step S203: YES).

[0065] Here, if the control unit 200 determines that adjustment instruction information has been input (step S203: YES), the process returns to step S106.

[0066] On the other hand, if the control unit 200 determines that the adjustment instruction information has not been input (step S203: NO), the process proceeds to step S107. The process from step S107 onwards is the same as that in FIG.

[0067] 7 shows a case where the position and angle adjustment process of the burner 103 is performed continuously at the timing when the optical fiber preform 10 reaches a predetermined pulling length, but it does not have to be performed continuously. For example, the pulling process of the optical fiber preform 10 and the position and angle adjustment process of the burner 103 may be performed at different times or under different conditions in the glass soot formation process.

[0068] As described above, the manufacturing apparatus 100 according to this embodiment can adjust the position and angle of the burner 103 even during the glass soot formation process. Therefore, in addition to the effects of the first embodiment, the position and angle of the burner 103 can be arbitrarily changed depending on the deposition state of the glass soot on the optical fiber preform 10, and the quality of the optical fiber preform 10 can be improved.

[0069] [Third embodiment] This embodiment differs from the second embodiment in that it further includes a function capable of switching the position / angle adjustment process of the burner 103 during glass soot formation based on setting information.

[0070] Fig. 8 is a flowchart showing an example of a process for forming glass soot in the manufacturing apparatus 100 according to this embodiment. Fig. 8 differs only in part from Fig. 7 described in the second embodiment. In the following, a description of the common processes will be omitted, and differences will be described in detail.

[0071] First, the control unit 200 acquires the lot information of the optical fiber preform 10 to be manufactured and the setting information related to the position and angle adjustment process inputted from the input operation unit 205 (step S301). After that, the control unit 200 performs the processes of steps S102 to S105 as in FIG. 7, and then the process proceeds to step S302.

[0072] In step S302, the control unit 200 refers to the setting information acquired in step S301 and determines whether or not to execute an adjustment process for the burner 103 during the formation of glass soot.

[0073] Here, when the control unit 200 determines that the adjustment process of the burner 103 is to be executed during the formation of glass soot (step S302: YES), the process proceeds to step S106. The processes of steps S106 to S203 are the same as those in FIG.

[0074] On the other hand, when the control unit 200 determines that the adjustment process of the burner 103 is not to be executed during the glass soot formation (step S302: NO), the process proceeds to step S107. The process after step S107 is the same as that in FIG.

[0075] As described above, the manufacturing apparatus 100 according to this embodiment further includes a function capable of switching the position / angle adjustment process of the burner 103 during the formation of glass soot based on setting information. Therefore, in addition to the effect of the second embodiment, the manufacturing apparatus 100 further achieves the effect that an operator can arbitrarily select an execution mode for the position / angle adjustment process of the burner 103.

[0076] [Fourth embodiment] This embodiment differs from the second embodiment in that it further has a function of adjusting the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 based on the length of time that the burner position adjustment device 115 sprays glass soot onto the target rod 107, i.e., the elapsed time.

[0077] Fig. 9 is a flow chart showing an example of a process for forming glass soot in the manufacturing apparatus 100 according to the present embodiment. Fig. 9 differs only in part from Fig. 7 described in the second embodiment. Therefore, in the following, a description of the common processes will be omitted, and differences will be described in detail.

[0078] First, the control unit 200 performs the processes of steps S101 to S105 in the same manner as in FIG. 7, and then the process proceeds to step S401.

[0079] In step S401, the control unit 200 determines whether or not the elapsed time from the start of the glass soot forming process has reached a predetermined time. If the control unit 200 determines that the elapsed time has reached the predetermined time (step S401: YES), the process proceeds to step S201. The processes in steps S201 to S203 are the same as those in FIG. 7.

[0080] On the other hand, when the control unit 200 determines that the elapsed time has not reached the predetermined time (step S401: NO), the control unit 200 continues the glass soot forming process under the same conditions until the elapsed time reaches the predetermined time.

[0081] As described above, the manufacturing apparatus 100 according to this embodiment further includes a function in which the burner position adjustment device 115 adjusts the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 based on the elapsed time from the start time of the glass soot formation process. Therefore, in addition to the effects of the second embodiment, even if the tip detection sensor 105 is not provided, the manufacturing apparatus 100 further achieves the effect of being able to estimate the tip position of the optical fiber preform 10 in the reaction vessel 101 based on the length of elapsed time and control the positions and angles of the optical fiber preform 10 and the burner 103.

[0082] It should be noted that the above-described embodiments are merely illustrative examples of the implementation of the present invention, and the technical scope of the present invention should not be construed as being limited thereby. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

[0083] [Modified embodiment] In the above embodiment, a configuration in which one burner 103 is provided in one manufacturing apparatus 100 has been described, but the number of burners 103 is not limited to one, and may be multiple. In this case, it is sufficient that at least one of the multiple burners 103 is configured so that the distance and angle to the optical fiber preform 10 can be adjusted.

[0084] In the above embodiment, the burner 103 is configured to be movable in two directions, the A direction and the Y direction, but it may be configured to be movable in the horizontal direction (the X direction perpendicular to the A direction and the Y direction in the figure). The structure for changing the inclined surface 113a is not limited to the above.

[0085] Furthermore, in the above embodiment, the manufacturing apparatus 100 is of a vertical type, but the manufacturing apparatus 100 to which the present invention can be applied is not limited to a vertical type, and may be of a horizontal type.

[0086] In the above embodiment, a configuration has been described in which the position and angle of the burner 103 are automatically adjusted when the optical fiber preform 10 reaches a predetermined pulling length detected by the tip detection sensor 105 or when a predetermined time has elapsed since the start of the glass soot formation process. However, the position and angle of the burner 103 may be manually adjusted by an operator, or the position and angle of the burner 103 may be adjusted based on conditions other than the detection signal of the tip position of the optical fiber preform 10 or the length of elapsed time.

[0087] For example, the manufacturing apparatus 100 may further be provided with a distance measuring sensor for measuring the distance from the burner 103 to the optical fiber preform 10. In this case, the control unit 200 can adjust the position and angle of the burner 103 based on a detection signal of the distance measured by the distance measuring sensor.

[0088] Furthermore, the positional relationship between the optical fiber preform 10 and the burner 103 and the angle of the burner 103 may be automatically adjusted by combining a first condition regarding the detection of the tip position of the optical fiber preform 10 by the tip detection sensor 105 and a second condition regarding the elapsed time since the start of the glass soot formation process. [Explanation of symbols]

[0089] 10 Optical fiber preform (glass soot preform) 10a: Inner deposition soot 10b...Outer deposition soot 100...Manufacturing equipment 101... Reaction vessel 101a...1st side wall 101b...Second side wall 101c Ceiling 101d...Bottom 102 Opening 103 Burner 104...Exhaust mechanism 104a Exhaust port 104b Valve 105 Tip detection sensor 105a Laser emission unit 105b Laser receiving section 106 Rotation and lifting mechanism 107···Target Rod 108....Sealing member 109 Heat-resistant packing 110···Flange 111···Fixing screw 112... Burner support member 112a...Gripping part 112b... First fixing member 112c... Fastening hardware 112d...Second fixing member 113...Pedestal 113a...Slope surface 114a Combustion gas supply device 114b Combustion gas supply line 114c Glass raw material gas supply device 114d Glass raw material gas supply line 115 Burner position adjustment device (adjustment mechanism) 200...Control section 201···CPU 202...ROM 203...RAM 204...Non-volatile memory 205 Input operation section 206...Display section 207a~207f Drive circuit

Claims

1. a reaction vessel in which a starting substrate is placed; a burner that is inserted from an opening of the reaction vessel and sprays glass soot onto the starting substrate within the reaction vessel; a seal member having an internal space for accommodating the burner, being expandable and contractable according to the position of the burner, and airtightly connecting the opening and the internal space; Equipped with The seal member includes at least a first connecting portion that connects to the opening and a second connecting portion that connects to the burner.

2. An optical fiber preform manufacturing apparatus comprising:

2. The opening and the sealing member are airtightly connected with a heat-resistant packing therebetween.

2. The apparatus for manufacturing an optical fiber preform according to claim 1.

3. A burner support member provided outside the reaction vessel and supporting the burner; an adjustment mechanism for adjusting a distance from the burner to the starting substrate and an angle between the burner and the starting substrate; 3. The apparatus for manufacturing an optical fiber preform according to claim 1, further comprising:

4. The adjustment mechanism adjusts the position and the angle of the burner by driving the burner support member.

4. The apparatus for manufacturing an optical fiber preform according to claim 3.

5. The adjustment mechanism adjusts the position and the angle of the burner based on a length of time for which the glass soot is sprayed onto the starting substrate.

5. The apparatus for manufacturing an optical fiber preform according to claim 4.

6. the adjustment mechanism adjusts the position and the angle of the burner based on lot information of an optical fiber preform to be manufactured.

6. The apparatus for manufacturing an optical fiber preform according to claim 4 or 5.

7. The burner support member further includes a base having an inclined surface on which the burner support member is placed, The adjustment mechanism adjusts the distance by driving the burner support member along the inclined surface, and adjusts the angle by changing the inclination angle of the inclined surface.

7. The apparatus for manufacturing an optical fiber preform according to claim 4, wherein the optical fiber preform is a tubular member.

8. The sealing member is formed in a bellows shape in the longitudinal direction.

8. The apparatus for manufacturing an optical fiber preform according to claim 1, wherein the optical fiber preform is a tubular member.

9. placing a starting substrate in a reaction vessel; a step of airtightly connecting an opening of the reaction vessel to the internal space by a seal member having an internal space for accommodating a burner and capable of expanding and contracting according to a position of the burner; spraying glass soot onto the starting substrate from the burner inserted through the opening; adjusting the position of the burner; Equipped with The seal member includes at least a first connecting portion that connects to the opening and a second connecting portion that connects to the burner.

2. A method for manufacturing an optical fiber preform comprising the steps of:

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