Patent Application
20080056644
The present invention relates to connecting members manufactured by molding or forming using a mold.
A connecting member such as a fiber optic connector has a plurality of fine holes 12, as shown in
These connecting members are manufactured using a mold, such as the one 20 shown in
A connecting member 10 is produced as follows: The leading ends 21′ of the fine hole forming pins 21 and the leading ends 23′ of the pins 23 for forming the guide pin insertion holes are inserted in the pin receiving holes 26 for the fine hole forming pins, and the pin receiving holes 27 for the pins for forming the guide pin insertion holes, respectively. Then, from a resin injection nozzle (not shown), a resin composition is injected into the inner space of the mold surrounded by the upper mold 31, the lower mold 30, the positioning member 28 and the pin mold 25 so that the injected resin composition will be hardened therein into a molded product.
The resin composition used for the molding is comprised of a resin or plastic material and a filler mixed in the resin. In the conventional art, the size of filler particles is chosen to be less than the space formed between the fine hole forming pins 21 in order that the resin composition can easily pass through the space between the fine hole forming pins 21. (See for example, Patent Document D1)
Such a fiber optic connector is used to connect optical cables. Typically, for the connection, optical glass fibers having an outer diameter of 125 μm are arrayed with the fiber-to-fiber distance of 250 μm.
The recent development of optical connection technology or “interconnection” technology for optically interconnecting CPU boards requires higher density of the spacing; for example, the fiber-to-fiber distance or pitch of 125 μm has been proposed. To address such high density requirement, the pitch of the fiber optic connector has to be made smaller accordingly.
In general, the use of resin composition containing filler particles of small diameters improves the transfer rate of the resin composition so that a molded product having reduced surface roughness is produced. (Lecture Papers of Plastic Working Spring Lecture Meeting, P 145, 2004 “Development of Transfer Assessment Using Accurate and Fine Mold”)
Therefore, it is expected that the connecting member disclosed in the patent document D1 has improved properties in terms of the transfer rate and the surface roughness.
Patent Document D1: Japanese Patent Application Publication 2004-86089
Problem to be Solved
However, the above mentioned conventional connecting members have the problems as follows: In general, to attain a smaller-sized connecting member with higher density and integration, and multiplicity of optical fibers, it is necessary to make smaller the pitch between the fine holes than that of the conventional connecting member. In addition, it is necessary to provide higher manufacturing accuracy of the connecting end face (corresponding to the one end face 11) of the connecting member.
More specifically, according to the Patent Document D1, all filler particles are sized to be able to pass the space formed between the fine hole forming pins 21: for example, for the space of 35 μm between the fine hole forming pins 21, filler particles having diameters less than 30 μm are used. The molded connecting member using the resin composition containing such filler particles has a uniform distribution of filler particles therein. As a result, the hardness of the resin around the array 12′ of the fine holes 12 is made essentially the same as the hardness of the resin between the fine holes 12. Hence the fine holes 12 cannot keep their dimensional accuracy since any external stress can deform the fine holes 12.
Solution
With the problems in mind, the present invention provides a connecting member in which filler particles having relatively small diameters are distributed between fine holes of the connecting member whereas filler particles having relatively large diameters are distributed around the array of the fine holes so that an outer portion surrounding the array of the fine holes has relatively high hardness, thus assuring dimensional accuracy of the fine holes.
A first aspect of the present invention provides a connecting member made of a resin composition, the connecting member having one end face in which a plurality of fine holes are arrayed in a horizontal row with a pitch P therebetween, each hole having a diameter of a φ or less, and guide pin insertion holes are each formed on either side of the array of the fine holes, wherein:
the resin composition contains a resin and filler particles mixed therein; and
a space (P−a) formed between the fine holes meets the following formula;
Dm<(P−a)<Dmax
in which Dmax represents a largest diameter of the filler particles, and Dm represents a most frequent diameter of the filler particles.
A second aspect of the connecting member is further configured such that the space (P−a) between the fine holes meets the following formula;
Dm<(P−a)≦Dc
in which Dc represents a diameter of the filler particles for which filler particles having diameters between the diameter Dc and the largest diameter account for 20% of the total number of the filler particles.
A third aspect of the present invention provides a connecting member made of a resin composition, the connecting member having one end face in which a plurality of fine holes are spaced by a pitch P therebetween to form an array in one horizontal row or a plurality of horizontal rows with a vertical distance therebetween, wherein:
a diameter of the fine holes is given by a φ, a row-to-row distance of the fine holes is given by h which is, however, zero when the number of the rows of the fine holes is one, a diameter of the guide pin insertion holes is given by b φ, the pitch between the fine holes is given by P, a space formed between each one of the guide pin insertion holes and nearest one of the fine holes is given by x, a center-to-center distance between each one of the guide pin insertion holes and the nearest one of the fine holes is given by L1,
wherein:
the following formula is met;
1<(x/(P−a))<10, and Dm<x
in which x is given by x=(L12+(h/2)2)0.5−2/a−2/b, and Dm represents a most frequent diameter of the filler.
A fourth aspect of the present invention provides a connecting member of claim 3 wherein the following formula is met;
0.5<((x/(P−a))/(b/a))<2, and x/(P−a)=0.5 to 2.
A fifth aspect of the present invention provides a connecting member wherein the following formula is also met;
x/x0 =0.3 to 3,
in which x0 represents a space formed between a side face of the connecting member and each one of the guide pin insertion holes.
A sixth aspect of the present invention provides a connecting member wherein optical fibers are accommodated in the fine holes.
A seventh aspect of the present invention provides a connecting member wherein hollow tubes are accommodated in the fine holes.
A eighth aspect of the present invention provides a connecting member having the one end face and the other end face opposite to the one end face, wherein the other end face is provided with a linear element arranging unit in which a plurality of linear elements covered with a coating are arranged, wherein a cavity is formed between the linear element arranging unit and the fine holes of the connecting member, the fine holes are formed in the one end face, and the fine holes communicate with the linear element arranging unit via the cavity so that the linear elements with the coating removed are accommodated in the fine holes such that the linear elements with the coating removed are arranged with a bend in the cavity, wherein:
the cavity has a length Lf in the longitudinal direction of the fine holes, the length Lf meeting the formula;
Lf≧2×(R2−(R−Δ/2)2)0.5
R=30/0.125×a1
in which R represents a curvature radius, a1 represents an outer diameter of the linear elements, a2 represents an outer diameter of the coating, Δ is given by Δ=(1/2) ×(n−1)×(a2−P), in which n represents the number of the fine holes arrayed in a row, and P represents the pitch of the fine holes.
In accordance with the present invention,a predetermined amount of filler particles greater than the space formed between the fine holes is also mixed into the resin composition in order that during the molding filler particles flows such that relatively small-sized filler particles will pass through the space between the fine holes while relatively large-sized filler particles will not pass through the space.
As a result, density of the filler around or outside of the array of the fine holes is increased, so that the mechanical strength around the array of the fine holes is improved while at the same time manufacturing accuracy of the product is improved; the surface roughness is reduced between the fine holes where relatively small-sized filler particles are situated.
With respect to filler particle sizes, it is not necessary to use filler particles having the same maximum size. Hence a low-cost manufacturing can be realized.
Regardless of the maximum diameter of the filler particles, the resin containing those filler particles with a most frequent diameter smaller than the space formed between the fine holes will penetrate into that space. Therefore, the invention can provide a molded product with the fine holes having a smaller pitch than that of the conventional molded product
A connecting member of the invention will be described in more detail in conjunction with the drawings.
Respective dimensions of the connecting member 10, specifically, height H, width W, depth D, pitch P between the fine holes 12, space (P−a) formed between the fine holes 12, vertical pitch h between fine hole 12 rows, diameter b φ of the guide holes 13, and pitch L of the guide holes 13 are given by:
More specifically, filler particles contained in a resin composition used here have a size-frequency distribution such that the most frequent filler particle diameter (the one having the highest frequency) is near 35 μm which is smaller than the space (P−a) formed between the fine holes 12, and that the maximum diameter of the filler particles is about 100 μmφ. Further, the resin composition of the embodiment contains filler particles such that filler particles having diameters between the space (P−a) formed between the fine holes 12 and the maximum filler particle diameter Dmax account for about 20% of the total. number of the filler particles contained in the entire resin composition.
As indicated in
With the present arrangement, an improved molding is realized, thus providing a smaller sized fiber optic connector with optical fiber multiplicity, higher density and integration features.
More specifically,
In general, the dimension b of the guide hole forming pins 23 is larger than the dimension a of the fine hole forming pins 21. Accordingly, the guide hole forming pins 23 has a greater flow resistance so that assuming the same initial flow velocity, the area of the space x will experience a flow deceleration greater than that of the area of the space (P−a). Therefore, it is preferred that the ratio x/(P−a) is set to a value about 0.5 to 2.0 times b/a.
Connecting members were produced which meet this condition.
Fine holes are for 12 optical fibers by 2 rows. P=125 μm, a=80 μm, L1=610 μm, h=250 μm, b=400 μmφ, P−a=45 μm, x=380 μm, x/(P−a)=8.4, b/a=5, x0=200 μm, and x/x0=1.9.
Other dimensions, i.e., height H, width W, depth D, pitch L between the guide holes (see
x=(L12+(h/2)2)0.5−2/a−2/b.
Fine holes are for 6 optical fibers by 2 rows. P=250 μm, a=125 μm, L1=675 μm, h=250 μm, b=500 μmφ, P−a=125 μm, x=407 μm, x/(P−a)=3.3, b/a=4, x0=150 μm, and x/x0=2.7.
Other dimensions, i.e., height H, width W, depth D, pitch L between the guide holes (see
x=(L12+(h/2)2)0.5−2/a−2/b.
As a result, since the molded product has a similar rate of material contraction on right and left sides of the fine hole, the dimensional accuracy of the fine holes and the neighborhood thereof is not reduced. Further, since the asymmetric diversity of the density is relatively small, deformation of the holes due to application of weight during use of the molded product is not likely to occur. Further, since the material flow rate on the right side of the fine hole forming pin can be controlled to be similar to the material flow rate on the left side of the fine hole forming pin, the fine hole forming pin will not be bent, thus providing a high accurate arrangement. In either of the examples, the fine holes were manufactured with the dimensional accuracy of 0.5 μm or less.
The advantages over the prior art are as follows: In the prior art, dimensions or spaces are so large, as in x=1900 μm, x0=550 μm, x/x0=3.45,L=4600 μm, W=6400 μm, D=8000 μm, and H=2500 μm that the dimensional accuracy is low and resistance to deformation during the use is low. In contrast, the present examples are configured with optimal spaces and distances and, therefore, can provide a high accuracy connecting member with a high resistance to deformation during the use of the connecting member.
Setting (P−a) and x to appropriate values, respectively, as in the present examples results in a substantially uniform density of filler particles in the right and left neighborhoods of each fine hole.
Therefore, the advantages include: The material contraction ratio in the right neighborhood of a fine hole will not significantly differ from the material contraction ratio in the left neighborhood thereof. The dimensional accuracy in the vicinity of the fine holes is improved. Since the asymmetric diversity or unevenness of the material is minimized, deformation of the fine holes due to application of weight during the use is unlikely to occur.
It is recognized that the outmost bare optical fiber 42 is most bent. The outmost optical fiber 42 has to be arranged so as to have a bend radius greater than the permissible minimum curvature radius that assures a minimized optical transmission loss.
Accordingly, given the bend radius of the fiber by R, the cavity 40 has to have a length Lf meeting the formula:
Lf≧2×(R2−(R−Δ/2)2 )0.5
R=30/0.125×a1
where R represents the curvature radius, a1 represents the outer diameter of the bare optical fiber, a2 represents the outer diameter of the coated optical fiber,
Δ=(1/2)×(n−1)×(a2−P)
where n represents the number of the fine holes arrayed in a row, P is the center-to-center distance or pitch between the fine holes.
Using this arrangement, a connecting member with minimized transmission loss is provided.
Although the fine holes accommodate optical fibers as linear elements according to the fourth embodiment, the present invention can also be used to an application in which the fine holes accommodate other linear elements such as nylon tubes and glass capillary tubes. In such cases, the tubes are tightly fit in the fine holes without forming a space between the surface of the tubes and the walls of the fine holes. Therefore, working liquid in the tubes can be sealed and flow therein without leakage by abutting and connecting end faces of connecting members with the tubes incorporated therein. The present invention is particularly useful in such an application since the application requires high axial accuracy and high flatness of the end face such that even if the pressure within the tubes reaches as high as 2 Mpa, the molded product will keep its form without leakage of the liquid.
Although an array of a plurality of optical fibers has two rows in any of the above embodiments, the present invention can also be applied to an optical fiber array having a single, or three or more rows of optical fibers. In such cases, relatively large sized filler particles are arranged similarly in the outer area around the fine hole array, thus increasing the material hardness in the outer area while relatively small sized filler particles are arranged in the inner area between the fine holes, thus improving manufacturing accuracy of the fine holes.
FIG.2
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-280346 | Sep 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/17614 | 9/26/2005 | WO | 4/27/2007 |
