Optical fiber core

[Detailed Description of the Invention]

The present invention relates to optical fiber cable core structure, and is Ah and the conventional optical fiber cable core Oh! Forgery, As shown in Drawing 1, it is optical fiber 1. It accomplished 41"4 from secondary covering 8 which consists of plastics, such as Be strong buffer layer 2 from silicon rubber, and nylon, and the diameter of an optical fiber of 125 micrometers, the diameter of a buffer layer of 400 micrometers, and diameter of secondary covering 9007zm were made into the standard power value, and firm business was carried out. At this time, the coefficient of linear expansion of an optical fiber isX[ 8.4 ] 10. It was, and at low temperature, contraction of secondary covering was very large as compared with the optical fiber, the coefficient of linear expansion of secondary covering is 1xlO, and there was [ the bend occurred in the optical fiber by contraction of secondary covering, and ] a fault which an optical loss increases. Extension of secondary covering at the time of a secondary covering extrusion process was eased by the long time, and it became the contractile force of secondary covering from the characteristic side with the passage of time, and acted on the optical fiber, the bend occurred in the optical fiber, and there was a fault which an optical loss increases. Conventionally, the contractile force of this secondary covering and the relation of increase h1 in an optical loss were not clear, and the optimal cable core structural design was not made from the field of temperature % nature, the water pressure characteristic, and the characteristic with the passage of time. it is Dimensions -- two processes were taken to cover 2.2nd buffer layer covering 8 with this structure around fiber l, and the cost of materials and a conversion cost were quotient values. in order that the present invention may remove these faults -- Warm -- the characteristic, the water pressure characteristic, and the characteristic with the passage of time are good, and clarify economical cable core structure. A detailed description of the invention is carried out to p dishes with a drawing. Drawing 2 is a sectional view of one example of the present invention, and is the two-layer cable core structure which covered buffer layer 2 further around fiber 1. By the difference between fiber l and the heat # tension coefficient of buffer N2, when cable core temperature falls, a cable core is contracted. Contractile force F which acts on a fiber at this time is approximately shown by the following formula. F=E □ fist S□ -beta, - delta t (1) However, Young's modulus of E□:M Impulse, S□: The cross-sectional area of a buffer layer, beta□: The coefficient of linear expansion of a buffer layer, deltat : it will be connected with the increase in an optical loss, if some music Si of an optical fiber cable core grows when the temperature change machine of atmosphere with which the cable core was placed, and contractile force F act. As shown in Drawing 8, it is initial modification W of an optical fiber. Is -- generally it is given with a following formula. Wo= a sln 7 (2) however an a:v high price, X: A value, 2t which shows the position of the direction of an axis of a fiber: The eccentricity from the pitch of initial modification and the cable core center of Strand is given by e. Maximum serious type Wmax of a fiber when contractile force F acts on a cable core arises in X-4, and is shown by the following formula. Up However, Fn = it is already q. E : Young's modulus of an optical fiber, Engineering: The example computation of Wmax and E□ is shown in the secondary section moment (=64dl', df: fiber outside diameter) of an optical fiber, and Drawing 4. However, it was referred to as deltat-80-degreeC and e==1. WInax becomes small as 4th [ The ] figure Yo pd (d: cable core outside diameter) becomes small -- d= 0.4 mm, E, and = 20kg/mm" -- being connected with"mu Increase loss, even if about 1% of wave high prices [ a ] Okay. Wmax increases but cable core temperature changes below -- Cowpea -- things are understood. Each - low-temperature characteristic of the optical fiber of the eight-layer structure cable core conventionally used for Drawing 6 and the two-layer structure cable core of the present invention is shown. As for it, the optical fiber of 92 layers of 5th [ The ] figure Yo structure cable core turns out that a loss does not change in low temperature. Coefficient of linear expansion beta of a cable core is given by a formula (4). However, S: The cross-sectional area of optical fiber 1, E: Young's modulus of optical phi * Ba 1, beta. : Optical fiber 10 coefficient of linear expansion, beta□ : the relation between the increase in a loss of a cable core when temperature of a cable core is set to minus 30 degreeC, and coefficient of linear expansion beta of a cable core is shown in the coefficient of linear expansion of buffer layer 2, and Drawing 6. Drawing 6 beta is 10. When it becomes large, it turns out that a loss increases rapidly. Coefficient of linear expansion beta of the cable core for which it asked from the formula (4), and the relation of cable core outside diameter d are shown in Drawing 7. However, a Strand outside diameter is set to 125pm, and they are E = 7800 kg/rnrn2 and beta. = It was referred to as 8.4x10-7 and beta□=1xlO. In order to make Drawing 7 beta or less into ten, at dlo and 8 mm, it is E□<=40ky/mm2, and is 47mm" and d<=0.55mm1 to E<=20 at d<=0.4 mm. . Then, it turns out that it is necessary to consider it as E□<=1ok7/mm." The water pressure characteristic when the water pressure up to 500 atmospheres is impressed to an eight-layer structure cable core and a two-layer structure cable core is shown in Drawing 8. That a loss increases the 98 layers of 8th drawing-and-manual-arts structure cable core at 50 atmospheres or more understands [ at least 500 atmospheres of losses not changing, but having the stable water pressure characteristic, or ] a two-layer structure cable core. On the other hand, it may be necessary to be d>=0.2 mm at To which @ Reverses buffer layer 2 uniformly on fiber l by a manufacturing problem. In order to guarantee the intensity of the manufactured cable core, it is necessary to do blue Petit of a cable core. The concept of blue Petit is shown in Drawing 9. When contact width of pulley 4 and optical fiber cable core 5 is set to 2b, it is the maximum contact pressure P in the center. It is shown by the following formula from the theory of Is Herz. P Po=M100 (6) however P=T/R, T: Tension, R which act on a cable core: The radius of a pulley, nu,: The poisson ratio of a buffer layer, Si 2: The poisson ratio of the Buu Lee material, E2: It is the maximum contact pressure P to the Young's modulus of pulley material, and Drawing 10. The relation of fiber cable core outside diameter d is shown. However, 9 and a pulley radius were 50 m 1.7 which needs TP for the 2% proof test of a cable core. Since the Takeshi strength of the There was case for silicone Rubber which silicone rubber does not carry out is 0.4 k(ies)/mm ' 28 degrees as shock absorbing material, it is contact maximum pressure power P. Is 0.4 kg/mm" -- it is necessary to carry out the following Therefore, when it is considered as E□=10 kg/mm2, it turns out that it needs to be referred to as d>=0.2 mm. When E□ is made small, it turns out that d is made thickly. The value of each Young's modulus makes the value in room temperature the central value. the connoisseur who explained above -- in order to suppress Si and the increase in a loss accompanying the temperature change of a cable core, while selecting d and E□ moderately and suppressing increase of initial modification of a cable core -- the coefficient of linear expansion of a cable core -- 10 -- it is necessary to carry out the following In order to prevent the increase in a loss which arises with the water pressure in 50 atmospheres or more, it is necessary to change to the conventional eight-layer structure and to make it two-layer structure. It may be necessary to be d>=0.2 mm from the production technology side for covering a buffer layer uniformly. In 2% of blue Petit, in order to prevent Disconnect which silicone rubber does not carry out, it needs to be referred to as d>=0.2rnm, for example by E□<10ky/rrLm2. It is necessary to have the intensity which an optical fiber cable core is excellent in the temperature article, the water pressure characteristic, and manufacturability which were stated above, and bears proof Tist. The degree of duplication of the following conditions 1-4 is shown in Drawing 11 by making Young's modulus E□ of cable core outside diameter d and a buffer layer into a parameter. (For example, it is shown that number 4 in a figure is filling all of the four following conditions.) 1, d< 0.4 mm of change of the initial modification at the time of low temperature, E <=20kq/mm"2, a coefficient of linear expansion (they are 23 and blue Petit intensity 27 mm to 10-'d<=0.8mm, E <=40ky/mm"d<=0.4mm, E, <=20 kp/mmd<=Q, 55 mm, and E <=10) d>=0.2 mm E <=10ky/mm"4, d>=0.2 mm of manufacturability four conditions of the 11th more than Drawing work -- filling -- 0.2 -- < (it turns out that it must be considered as i<=0.4(mm) Cut E 1 <=10 kg/m-.) There is an advantage, like the optical fiber cable core of the present invention has a small change of the loss accompanying a temperature change compared with the conventional eight-layer structure cable core, and its loss change by water pressure is small, and it bears 2% of blue Petit, and is excellent in manufacturability, and a manufacturing process is also excellent in economical efficiency few as explained above.

[Brief Description of the Drawings]

In the sectional view of the conventional optical fiber cable core, and Drawing 2, Drawing 1 is sectional views of one example of cable core book '4 Construction of the present invention, In Drawings 4, Drawing 8 is a figure showing the model of optical fiber modification, and a figure showing the relation between the Young's modulus of a buffer layer, and the rate of change of the initial modification accompanying a temperature change, In the key map of blue Petit, and Drawing 10, the water pressure characteristic figure of a cable core and Drawing 9 are [ the figure in which Drawing 5 shows the low-temperature characteristic figure of a cable core, and Drawing 6 shows the coefficient of linear expansion of a cable core, and the relation of the increase in an optical loss, the figure in which Drawing 7 shows the relation of coefficient of linear expansion beta of cable core outside diameter d and a cable core, and Drawing 8 ] fiber cable core outside diameter d and contact maximum pressure power P. the figure showing connection of, and Drawing 11 -- the optimal parameter of a two-layer structure cable core -- " -- it is a shown figure. l [ .. Optical fiber cable core. ] ... An optical fiber, 2 ... A buffer layer, 8..secondary covering, 4 ... A pulley, 5 Applicant for a patent Drawing 1 of a Japan Hiroshi 1B' Marketing public corporation The 21st The The 37'4th Drawing 4 Drawing 5 Warm 7k ('C) The 61st The The number rho of Tang Zhuang for cotton (degreeC) 71st Di Z1 11, - and the diameter of Nishiki fF d It is 4 the 81st degree. Water pressure (* f) '7C Drawing 9 Tpkg Drawing 10 The diameter [ of A * Thread spur [] d (mWL) 11th A 1 1U Emperor 9 (fL d (mtn) 23-)