US20040106362A1 - Jig plate and end face polishing method - Google Patents

Abstract

A jig plate is opposed to a polishing plate, for polishing the face of a ferrule cylindrical member in contact with the polishing plate at a predetermined angle into a convex curve inclined relative to a plane perpendicular to the axis. The jig plate includes a holding part for detachably holding an optical connector plug to a jig plate body having a mounting part to an end face polishing machine. The holding part holds the optical connector plug while correcting the target direction of the inclination of the polished convex curve of the ferrule cylindrical member held by the optical connector plug to turn in the direction opposite to the rotating direction of the polishing plate with respect to a plane including the center of the jig plate body and the axis of an optical fiber. Thus the direction of inclination coincides with the reference direction of the optical connector plug.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention[0001]
• The present invention relates to a jig plate provided to an end face polishing machine, for holding an optical connector plug and an end face polishing method using the same.[0002]
• 2. Description of the Related Art[0003]
• In order to reduce connection loss at a connector connecting part and to decrease reflected return light, general optical connectors used in optical communication and the like use an Angle physical contact (PC) connector in which the end face of an optical fiber held in a ferrule cylindrical member is polished together with the end face of the ferrule cylindrical member diagonally relative to a plane perpendicular to the axis of the optical fiber into a convex curve.[0004]
• The Angle PC connector includes an optical connector plug formed of a ferrule cylindrical member for holding the optical fiber and a plug housing for holding the ferrule cylindrical member and an optical connector adapter for optically connecting the optical connector plugs inserted from opposite ends thereof.[0005]
• When the opposed optical connector plugs are connected through the optical connector adapter, the ferrule cylindrical member is held in the plug housing in a state in which the rotational movement about the axis of the ferrule cylindrical member is restricted in order to control the direction of eccentricity of the ferrule cylindrical member to reduce insertion loss.[0006]
• The ferrule cylindrical members are held in the plug housing such that they are freely moved axially by a predetermined distance while being urged toward the axial end with respect to the plug housing and the end faces are brought into contact with each other for optical connection under a predetermined pressure in the optical connector adapter.[0007]
• In order to hold the ferrule cylindrical member so as to be axially moved by a predetermined distance, an optical connector is proposed in which a key provided in the plug housing for controlling the rotational movement and a key groove provided in the flange of the ferrule are brought into engagement with each other and a predetermined space is provided between the key and the key groove so that the ferrule can move in the axial direction (for example, refer to Patent Document 1).[0008]
• The ferrule cylindrical member of the optical connector plug and the end of the optical fiber are polished into a convex curve inclined relative to a plane perpendicular to the axis by using an end face polishing machine in which the ferrule cylindrical member and a rotating and fluctuating polishing member are brought into contact with each other, with the optical connector plug in the above-described state.[0009]
• The end face polishing machine includes a polishing plate having a polishing surface shaped in a circular cone that increases in height from the outer periphery toward the center, with the angle formed by the rotation axis (an axis of rotation or an axis of revolution) and a vertical plane being a very small angle Δ and a jig plate for holding the optical connector plug in the opposite position relative to the polishing plate. The jig plate is moved toward the polishing plate to thereby bring the end of the ferrule of the optical connector plug into contact with the polishing member on the polishing plate,, thereby performing the Angle PC polishing (for example, refer to Patent Document 2).[0010]
• The jig plate used in the known end face polishing machine, however, holds the plug housing of the optical connector plug. Therefore, when the ferrule cylindrical member is brought into contact with the rotating and fluctuating polishing member at a predetermined angle, the ferrule is displaced in the direction of rotation around the axis of the optical fiber because of a space formed between the plug housing and the flange of the ferrule. This produces the problem that the direction of inclination of the polished convex curve of the ferrule cylindrical member does not pass through the axis of the optical fiber, so that the center of polishing in contact with the polishing member comes out of the center of the optical fiber, and thus the center of curvature formed on the end face shifts from the axis of the optical fiber in the direction perpendicular to the direction of inclination of the end face.[0011]
• In the Angle PC polishing, since the polishing plate is rotated and fluctuated, the ferrule cylindrical member is polished by the polishing member to form a trochoid trail. This increases the amount of polishing on the end face of the ferrule cylindrical member in the direction of rotation of the polishing plate in the region of a trail described by the ferrule cylindrical member moving upward on the polishing surface inclined from the center toward the rim. On the other hand, this decreases the amount of polishing on the face opposite to the direction of rotation of the polishing plate in the region of a trail described by the ferrule cylindrical member moving downward on the polishing surface inclined from the rim toward the center. This produces the problem that the amount of polishing on the face of the ferrule cylindrical member cannot be even, thereby causing unsymmetrical wear, so that the center of curvature of the face shifts from the central axis of the optical fiber in the direction perpendicular to the direction of inclination of the end face.[0012]
• [Patent Document 1][0013]
• JP-A-1-216304 (p. 2, FIG. 6)[0014]
• [Patent Document 2][0015]
• JP-A-8-112745 (p. 3, FIG. 1)[0016]
SUMMARY OF THE INVENTION
• Accordingly, in view of the above problems, the present invention provides a jig plate and an end face polishing method capable of reducing the displacement between the center of curvature of the end face of a ferrule cylindrical member that is diagonally PC-polished and the central axis of an optical fiber, thereby reducing insertion loss.[0017]
• In order to solve the above problems, a jig plate according to embodiments of the present invention is provided which is opposed to a rotating and fluctuating polishing plate of an end face polishing machine for polishing the end face of a ferrule cylindrical member that holds the end of an optical fiber, for polishing the face of the ferrule cylindrical member into a convex curve inclined with respect to a plane perpendicular to the axis, with the ferrule cylindrical member brought into contact with the polishing plate at a predetermined angle. A jig plate body having a mounting part to the end face polishing machine includes a holding part for detachably holding an optical connector plug, wherein the holding part holds the optical connector plug while correcting the target inclining direction of the polished convex curve of the ferrule cylindrical member so as to turn to a direction opposite to the rotating direction of the polishing plate with respect to a plane including the center of the jig plate body and the axis of the optical fiber so that the inclining direction of the polished convex curve of the ferrule cylindrical member held by the optical connector plug coincides with the reference direction of the optical connector plug.[0018]
• In a jig plate according to embodiments of the present invention, the reference direction of the optical connector plug is preferably determined with the outer periphery of the optical connector plug as the reference.[0019]
• In a jig plate according to embodiments of the present invention, the reference direction of the optical connector plug is preferably determined depending on the direction of a location key provided to the optical connector plug.[0020]
• In a jig plate according to embodiments of the present invention, the holding part of the jig plate body preferably holds the optical connector plug through a holding member for detachably holding the optical connector plug.[0021]
• In a jig plate according to embodiments of the present invention, the holding member can preferably be replaced with a holding member of a different correction angle.[0022]
• In a jig plate according to embodiments of the present invention, the optical connector plug is preferably held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.[0023]
• An end face polishing method according to embodiments of the present invention is provided wherein a ferrule cylindrical member is brought into contact with a polishing member at a predetermined angle with a jig plate, the polishing member being placed on a rotating and fluctuating polishing plate supported by a polishing machine body and the jig plate fixing an optical connector plug having the ferrule cylindrical member holding an optical fiber; and the face of the ferrule cylindrical member is polished into a convex curve inclined with respect to a plane perpendicular to the axis. The target inclining direction of the polished convex curve of the ferrule cylindrical member is corrected so as to turn to a direction opposite to the rotating direction of the polishing plate with respect to a plane including the center of the jig plate body and the axis of the optical fiber so that the inclining direction of the polished convex curve of the ferrule cylindrical member held by the optical connector plug coincides with the reference direction of the optical connector plug.[0024]
• In an end face polishing method according to embodiments of the present invention, the ferrule cylindrical member is preferably brought into contact with a polishing surface of the polishing member relatively at an angle and is polished so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.[0025]
• According to embodiments of the present invention, the use of a jig plate that polishes a ferrule cylindrical member in such a way that the target direction is determined in advance so that the inclining direction of a polished convex curve of the ferrule cylindrical member held by an optical connector plug coincides with the reference direction of an optical connector plug allows the inclining direction of the ferrule cylindrical member to coincide with the reference direction of the optical connector plug, thus reducing insertion loss during optical connection using the optical connector plug.[0026]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic sectional view of an end face polishing machine according to a first embodiment of the present invention;[0027]
• FIG. 2A and FIGS. 2B and 2C are a perspective view and sectional views of an example of an optical connector plug according to the first embodiment of the invention, respectively;[0028]
• FIG. 3 is a plan view of an end of the optical connector plug according to the first embodiment of the invention;[0029]
• FIGS. 4A and 4B are a perspective view and a side view of a jig plate according to the first embodiment of the invention, respectively;[0030]
• FIGS. 5A and 5B are a top view of and an enlarged view of the essential part of the jig plate according to the first embodiment of the invention, respectively;[0031]
• FIG. 6 is a sectional view of the jig plate according to the first embodiment of the invention;[0032]
• FIGS. 7A and 7B are plan views of the end face of a ferrule cylindrical member according to the first embodiment of the invention;[0033]
• FIG. 8A is a plan view of the trail of the ferrule cylindrical member and FIGS. 8B and 8C are schematic plan view of the end face of the ferrule cylindrical member, according to the first embodiment of the invention;[0034]
• FIG. 9 is a graph showing the relationship between the correction angle and the eccentricity according to the first embodiment of the invention;[0035]
• FIGS. 10A and 10B are an exploded plan view and a sectional view of an optical connector plug according to a second embodiment of the invention, respectively;[0036]
• FIG. 11 is a perspective view of a jig plate according to the second embodiment of the invention; and[0037]
• FIGS. 12A and 12B are a top view and a sectional view of the jig plate according to the second embodiment of the invention, respectively.[0038]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The present invention will be specifically described with reference to the embodiments.[0039]
• [First Embodiment][0040]
• FIG. 1 is a schematic sectional view of an end face polishing machine according to a first embodiment of the present invention.[0041]
• As FIG. 1 shows, the center of a first rotation-[0042]transmission board12 is secured to the rotation shaft of arotary motor11. A plurality of first connectingpins13 is fixed on the concentric circle with the rotation center as the fulcrum of the first rotation-transmission board12. The first connectingpins13 are rotatably connected to the respective eccentric portions of a rotation-transmission board14, to which second connectingpins15 are fixed. Each second connectingpin15 is rotatably connected to a second rotation-transmission board16.
• On the other hand, the center of a[0043]drive gear18 is secured to the rotation shaft of arevolutionary motor17. A drivengear19 is in engagement with thedrive gear18. The drivengear19 is secured to the lower periphery of a revolution-transmission shaft20. A bearingcylinder22 of a polishingmachine body21 is fitted on the upper periphery of the revolution-transmission shaft20. Arotary shaft23 is rotatably fitted at a predetermined distance from the center of rotation into the revolution-transmission shaft20. The lower end of therotary shaft23 is firmly fixed to the center of the second rotation-transmission board16.
• The upper end of the[0044]rotary shaft23 is connected to aplaten25 via a joint24. Theplaten25 has the upper surface inclined toward the center in a cone shape and rotates clockwise and fluctuates in this embodiment.
• A polishing[0045]member27 is provided on the top of theplaten25 via anelastic member26.
• The materials for the[0046]elastic member26 include rubber, elastomers, and resin.
• The polishing[0047]member27 provided on theelastic member26 includes a polishing sheet having abrasive coating made of diamond, silicone oxide, cerium oxide, and silicone carbide and a polishing stone.
• On the other hand, a[0048]jig plate40 having optical connector plugs100 that hold a plurality of ferrules is supported on the polishingmachine body21 with asupport mechanism30.
• The[0049]jig plate40 and the optical connector plugs100 held by thejig plate40 according to the embodiment will now be described.
• The optical connector plugs[0050]100 held by thejig plate40 of this embodiment will first be described. FIG. 2A and FIGS. 2B and 2C are a perspective view and sectional views of the optical connector plug, respectively; and FIG. 3 is a plan view of an end of the optical connector plug.
• The optical connector plugs[0051]100 according to the embodiment is an LC optical connector plug, as illustrated, and includes aferrule110, astopper120, an urgingspring130 provided between theferrule110 and thestopper120 for urging theferrule110 toward the axial end, and aplug housing140 for holding theferrule110 and thestopper120 therein.
• The[0052]ferrule110 includes a ferrulecylindrical member111 made of ceramic such as zirconia or glass and aflange112 provided at the rear end of the ferrulecylindrical member111.
• The ferrule[0053]cylindrical member111 has a cylindrical shape with an outside diameter of 1.25 mm and has an optical-fiber insertion hole113 therein in the axial direction for anoptical fiber1 to pass through.
• The ferrule[0054]cylindrical member111 has anend face111apolished by an end face polishing machine into a convex curve inclined relative to a plane perpendicular to the axis, as shown in FIG. 2C.
• Matching the center of curvature of the[0055]end face111aof the ferrulecylindrical member111 to the axis of theoptical fiber1 can reduce insertion loss during optical connection.
• The[0056]flange112 has an optical-fiber-core insertion hole114 that communicates with the optical-fiber insertion hole113 of the ferrulecylindrical member111 and allows an optical-fiber core wire2 having a coating on the outer periphery of theoptical fiber1 to pass through.
• The[0057]flange112 has aflange part115 projecting around the circumference, on the outer periphery of the end thereof. Theflange part115 has a hexagonal cross section and engages with a rotation stopper of the plug housing140 (specifically described later) to restrict the rotational motion of theferrule110 around the axis.
• The[0058]plug housing140 has aferrule insertion hole141 in the axial direction for theferrule110 to pass through.
• The[0059]ferrule insertion hole141 has aferrule projection hole142 having an inside diameter to project only the ferrulecylindrical member111 when engaging with the end of theflange part115 of theferrule110.
• The end of the[0060]flange part115 is in contact with the rim of the opening of theferrule projection hole142 so that the movement of theferrule110 toward the end is restricted.
• The[0061]ferrule projection hole142 has arotation stopper143 at the end adjacent to theflange112, thestopper143 coming in contact with the outer periphery of theflange part115 to restrict the rotational movement around the axis of theferrule110.
• The[0062]rotation stopper143 has a hexagonal cross section, like the cross section of theflange part115, and has a dimension to provide a space between it and the outer periphery of theflange part115 so that theflange part115 can move in the axial direction.
• The space causes the[0063]ferrule110 to rattle in the direction of rotation around the axis, with respect to theplug housing140.
• The[0064]ferrule insertion hole141 has thestopper120 fixed at the rear end thereof.
• The[0065]stopper120 has an optical-fiber-core insertion hole121 in the axial direction for the optical-fiber core wire2 to pass through, and has acommunication hole122 that communicates with the optical-fiber-core insertion hole121 and has an inside diameter slightly larger than that of the optical-fiber-core insertion hole121.
• The difference in the inside diameter between the optical-fiber-[0066]core insertion hole121 and thecommunication hole122 provides astep123.
• The[0067]communication hole122 holds the urgingspring130 therein, into which the rear end of theflange112 of theferrule110 is inserted.
• When one end of the urging[0068]spring130 comes into contact with the rear end of theflange part115 and the other end comes into contact with thestep123 of thestopper120, theferrule110 is urged to and held at the end of theplug housing140.
• The end face of the[0069]flange part115 is in contact with the opening rim of theferrule projection hole142 while being urged toward the end, as described above, so that theferrule110 is held with the movement toward the end restricted.
• In other words, the[0070]ferrule110 is pushed toward the rear end against the urging force of the urgingspring130, thereby being moved toward the axial rear end.
• The[0071]stopper120 is fixed such that an engagingprojection124 of thestopper120 and anengaging hole144 of theplug housing140 come in contact with each other.
• A[0072]boot150 formed of rubber or the like is fixed to the rear end of thestopper120 to prevent theoptical fiber1 from breaking.
• The[0073]plug housing140 has alatch145 on the outer periphery. Thelatch145 is integrated with theplug housing140 and is plastically transformable because one end is free.
• The[0074]latch145 detachably holds theoptical connector plug100 to the optical connector adaptor for optical connection and thejig plate40, which will be specifically described later.
• The[0075]optical connector plug100 needs to be polished so that the incliningdirection200 of theend face111aof the ferrulecylindrical member111, shown in FIG. 2C, coincides with thereference direction201 of theoptical connector plug100, shown in FIG. 3.
• The[0076]reference direction201 of theoptical connector plug100 is used to position theoptical connector plug100 to an optical connector adaptor (not shown) in the rotating direction around the axis of theoptical fiber1. In this embodiment, theoptical connector plug100 is of LC type and the cross section of theplug housing140 is shaped like a rectangle. Accordingly, the cross section of the insertion hole of the optical connector adapter for theoptical connector plug100 to be inserted is formed in the same rectangular shape as that of theplug housing140, so that theoptical connector plug100 is positioned to the optical connector adapter in the rotating direction around the axis of theoptical fiber1. In other words, in this embodiment, thereference direction201 is determined with the outer periphery of theoptical connector plug100 and thelatch145 as the reference; the direction orthogonal to adirection203 orthogonal to the surface of theplug housing140 of theoptical connector plug100 having thelatch145 is set to thereference direction201.
• The inclining[0077]direction200 of theend face111aof the ferrulecylindrical member111 is a plane direction including an outermost protruding point on the outer periphery of theend face111aand a rearmost protruding point, as shown in FIG. 2C. The incliningdirection200 includes the center of curvature that is the apex of the convex curve.
• When the inclining[0078]direction200 of thepolished end face111aof the ferrulecylindrical member111 deviates from thereference direction201, the center of curvature deviates from the axis of theoptical fiber1 to increase insertion loss when the optical connector plugs100 are optically connected with each other, which will be specifically described later.
• Therefore, it is necessary to polish the[0079]end face111aof the ferrulecylindrical member111 so that the incliningdirection200 of the polished convex curve of the ferrulecylindrical member111 coincides with thereference direction201 of theoptical connector plug100 to thereby reduce the eccentricity in the direction orthogonal to the incliningdirection200 including the center of curvature and the center of theoptical fiber1.
• The[0080]jig plate40 will then be described.
• FIGS. 4A and 4B are a perspective view and a side view of the[0081]jig plate40 according to the first embodiment of the invention, respectively; FIGS. 5A and 5B are a top view of and a partially enlarged view of thejig plate40; FIG. 6 is a sectional view taken along line A-A′ of FIG. 5A; and FIGS. 7A and 7B are plan views of the end face of the ferrulecylindrical member111.
• As illustrated, according to the embodiment, the[0082]jig plate40 holds the LCoptical connector plug100 and has ajig plate body50 having a plurality ofconcave holding parts51 around the periphery along the circumference and a plurality of holdingmembers60 detachably held by the respective holdingparts51.
• The[0083]jig plate body50 is shaped like a polygonal disk and has the holdingparts51 each having a trapezoidal opening in the vicinity of the periphery along the circumference.
• Each holding[0084]part51 has acylindrical tube52, at the bottom, which is fitted to the end of the ferrulecylindrical member111. Thetube52 has a throughhole53 in the axial direction for thejig plate body50 to pass through along the thickness. The ferrulecylindrical member111 of theoptical connector plug100 held by the holdingmember60 is inserted in the throughhole53 and only the end of the ferrulecylindrical member111 projects from the bottom of thejig plate body50.
• The[0085]tube52 has an outside diameter that can be fitted on the end of theplug housing140 of theoptical connector plug100. The end of theplug housing140 comes in contact with the bottom of the holdingpart51, so that the amount of the ferrulecylindrical member111 projecting from the bottom of thejig plate body50 is controlled.
• The holding[0086]part51 and thetube52 are provided at an inclination angle so as to hold the optical connector-plug100 by thejig plate40 such that the rear end of theoptical connector plug100 is inclined from the center to the periphery, relative to the thickness of thejig plate body50.
• The holding[0087]member60 held by the holdingpart51 has a holdinghole61 for theoptical connector plug100 to pass through along the thickness.
• The holding[0088]hole61 has alatch engaging part62 with which thelatch145 of theplug housing140 of theoptical connector plug100 is brought in engagement. When theoptical connector plug100 is inserted into the holdinghole61, thelatch145 is brought into engagement with thelatch engaging part62 and thus theoptical connector plug100 is detachably retained by the holdingmembers60.
• The holding[0089]member60 have the same shape as that of the holdingpart51 and is detachably retained by the holdingpart51. It is sufficient to retain thehold member60 to thejig plate body50 so as not to become disengaged in the direction of the thickness of thejig plate body50 and not to rotate around the axis of theoptical fiber1 with respect to thejig plate body50 and so the way of fixing is not particularly limited; for example, the holdingmember60 and thejig plate body50 may be fixed to each other with a screw (not shown).
• The holding[0090]hole61 in the holdingmember60 retains theoptical connector plug100 while correcting the target direction of the inclination of thepolished end face111aof the ferrulecylindrical member111 so as to rotate in the direction opposite to the rotating direction of theplaten25 with respect to the plane including the center of thejig plate body50 and theoptical fiber1 so that the incliningdirection200 of theend face111a, which is polished in convex curve, of the ferrulecylindrical member111 retained by theoptical connector plug100 coincides with thereference direction201 of theoptical connector plug100.
• When the ferrule[0091]cylindrical member111 is polished with thereference direction201 of theoptical connector plug100 coincided with the direction of a plane including the axis of theoptical fiber1 and the center of thejig plate body50, the ferrulecylindrical member111 is rotated around the axis of theoptical fiber1 by the polishingmember27 since the ferrulecylindrical member111 is held so as to cause rattle.
• When the ferrule[0092]cylindrical member111 rotates around the axis of theoptical fiber1, the incliningdirection200 of the inclined convex curve formed on theend face111aof the ferrulecylindrical member111 deviates from thereference direction201, as shown in FIG. 7A.
• Since the deviation of the inclining[0093]direction200 is formed on the convex curve where theend face111ais inclined relative to the plane perpendicular to the axis of theoptical fiber1, the ferrulecylindrical member111 is rotated with apoint212 different from thecenter210 of theoptical fiber1 as the center.
• Therefore, the[0094]center211 of curvature formed on theend face111ais formed eccentrically in thedirection203 orthogonal to the reference direction.
• The eccentricity L (μm) between the[0095]center210 of theoptical fiber1 and thecenter211 of curvature can be given by the following equation:
• [Equation 1][0096]
• L=γ/1000×sin θ×sin φ  (1)
• where γ (mm) is the radius of curvature, θ (degree) is the inclination angle of the[0097]end face111a, and φ (degree) is the rotation angle of the ferrulecylindrical member111 relative to theplug housing140.
• The eccentricity of the[0098]reference direction201 can be reduced by changing the contact angle formed by the axis of the ferrulecylindrical member111 and the polishingmember27 through the use of thejig plate40 or theplaten25. However, the eccentricity of thedirection203 orthogonal to thereference direction201 cannot be reduced even by changing the contact angle that the ferrulecylindrical member111 makes with the polishingmember27.
• Since the[0099]platen25 rotates or fluctuates, the polishing trail of the ferrulecylindrical member111 on the polishingmember27 becomes trochoid as shown in FIG. 8A. FIG. 8A is a plan view of the trail of the ferrulecylindrical member111 and FIGS. 8B and 8C are schematic plan view of the end face of the ferrulecylindrical member111, respectively.
• In the trochoid trail, a trail region a ascending the slope of the polishing[0100]member27 has a large polished quantity on one side, as shown in FIG. 8B and a trail region b descending the slope has a smaller polished quantity than that of the region a, as shown in FIG. 8C, thus causing unsymmetrical wear.
• In this way, also the inclination of the[0101]platen25 causes unsymmetrical wear in polished quantity to increase the eccentricity between thecenter211 of curvature and thecenter210 of theoptical fiber1.
• According to the embodiment, in order to handle the rattle of the[0102]ferrule110 in the rotating direction around the axis with respect to theplug housing140 and the deviation in polished amount, the holdinghole61 provided in the holdingmember60 is formed to correct the inclining direction of theend face111aso as to rotate in the direction opposite to that of theplaten25 around the axis of theoptical fiber1 and theend face111ais polished so that thereference direction201 of theoptical connector plug100 and the incliningdirection200 coincide with each other, as shown in FIG. 7B. Thus thecenter211 of curvature and thecenter210 of theoptical fiber1 can be coincided with each other.
• More specifically, as FIG. 5B shows, the holding[0103]member60 holds thereference direction201 of theoptical connector plug100 to the direction (target direction) rotated around the axis of theoptical fiber1 in the direction opposite to the rotating direction of theplaten25 with respect to the plane containing the center of thejig plate body50 and the axis of theoptical fiber1. Thus thereference direction201 and the incliningdirection200 are coincided with each other so that thecenter211 of curvature and thecenter210 of theoptical fiber1 are coincided with each other.
• The eccentricity between the[0104]center211 of curvature formed on theend face111aof the ferrulecylindrical member111 and thecenter210 of theoptical fiber1 was measured when polishing was performed with the correction angle of theoptical connector plug100 held by the holdingmember60 was set at zero degree, two degrees, and 2.5 degrees. The measurement is shown in Table 1.

  	TABLE 1
  	Correction	0	2	2.5
  	Angle
  	(degree)
  	Eccentricity	42.6	−9.2	−19.04
  	(μm)

• The measurement in Table 1 gives the approximate curves shown in FIG. 9. The approximate curves show that when the correction angle that is the angle of the target direction of the[0105]optical connector plug100 relative to the plane containing the center of thejig plate body50 and the axis of theoptical fiber1 is 1.5 degrees, the eccentricity becomes 0 μm. Accordingly, in this embodiment, the correction angle of theoptical connector plug100 retained by the holdingmember60 is set to 1.5 degrees as shown in FIG. 5B.
• In practice, even when the correction angle is set at 1.5 degrees, the[0106]end face111awith an eccentricity of 0 μm is not formed on every ferrulecylindrical member111, causing variation in eccentricity; however, the eccentricity can be reduced as small as 5 μm or less.
• Reducing the eccentricity can decrease the insertion loss when the pair of opposite optical connector plugs[0107]100 is connected with the optical connector adapter.
• The[0108]jig plate body50 has aboss54 serving as a mounting part supported by thesupport mechanism30, fixed in the center thereof with screws.
• On the other hand, the[0109]support mechanism30 includes a supportingpart31 provided to the polishingmachine body21 and anarm32 movably held by the supportingpart31, as shown in FIGS. 1 and 6.
• The[0110]arm32 retains thejig board40 by the end thereof engaged with theboss54 while restricting the rotational movement and the inclining movement of thejig plate40.
• Specifically, the[0111]boss54 of thejig plate40 includes arectangular recess56 and alid57 fixed to the opening end of therecess56 and having an opening smaller than therecess56.
• On the other hand, the end of the[0112]arm32 has arectangular flange33 in engagement with therecess56. Inserting theflange33 from the side of theboss54 into the recess56brings the side of theflange33 into-contact with the side of therecess56, thereby restricting the rotational movement.
• The[0113]flange33 inserted into therecess56 of theboss54 is brought into contact with thelid57 to thereby restrict the movement of thejig plate40 toward theplaten25.
• The[0114]arm32 thus retains thejig plate40 while restricting the movement of thejig plate40 in the directions of rotation and inclination.
• The[0115]arm32 that retains thejig plate40 in that way is provided to the supportingpart31 so as to be freely moved along the thickness of theplaten25 and pushes the plurality of optical connector plugs100 against the polishingmember27 on theplaten25 with a predetermined pressure.
• Pushing means for pushing the[0116]arm32 is not particularly limited; for example, thearm32 may be pushed manually or by the driving of a drive motor or a hydraulic pump. The pushing means may include a pressure sensor such as a load cell for determining the data on the pressure to push theoptical connector plug100 to the polishingmember27.
• [Second Embodiment][0117]
• The above described first embodiment has used the[0118]jig plate40 that holds the LCoptical connector plug100 as an example. The second embodiment uses a jig plate that holds an SC optical connector plug as an example. Components same as those of the first embodiment are given the same reference numerals and their description will be omitted.
• An optical connector plug held by the jig board according to the second embodiment of the invention will first be described. FIGS. 10A and 10B are an exploded plan view and a sectional view of the[0119]optical connector plug100A according to the second embodiment of the invention, respectively.
• The[0120]optical connector plug100A of this embodiment is an SC optical connector plug, as illustrated. Theoptical connector plug100A includes aplug housing140A that is fitted to the SC optical connector adapter, aplug frame160 fitted in theplug housing140A, aferrule110A that holds theoptical fiber1 that performs optical connection and is inserted from the back of theplug frame160, astop ring120A of which the end comes into engagement with the rear end of theplug frame160, and an urgingspring130A held between theferrule110A and thestop ring120A for urging theferrule110A toward the axial end.
• The[0121]ferrule110A includes a ferrulecylindrical member111A made of ceramic such as zirconia or glass and aflange112A provided at the rear end of the ferrulecylindrical member111A.
• The ferrule[0122]cylindrical member111A has a cylindrical shape with the outside diameter of 2.5 mm and has an optical-fiber insertion hole113A therein in the axial direction for theoptical fiber1 to pass through.
• The ferrule[0123]cylindrical member111A has anend face111apolished by the end face polishing machine to be formed in a convex curve inclined relative to the plane perpendicular to the axis in a manner similar to the ferrulecylindrical member111 of the first embodiment.
• Matching the center of curvature of the[0124]end face111ato the axis of theoptical fiber1 can reduce insertion loss during optical connection.
• The[0125]flange112A has an optical-fiber-core insertion hole114A that communicates with the optical-fiber insertion hole113A of the ferrulecylindrical member111A and allows the optical-fiber core wire2 having a coating on the outer periphery of theoptical fiber1 to pass through.
• The[0126]flange112A also has aflange part115A projecting around the circumference, on the outer periphery thereof. Theflange part115A has a circular cross section and haskey grooves116 fitted on engagingprojections163 of theplug housing140A, which will be specifically described, at intervals of 90 degrees at four points around the circumference. Thekey grooves116 engage with the engagingprojections163 of theplug frame160, thereby restricting rotational movement around the axis of theferrule110A.
• The number, position, depth, shape and so on of the[0127]key grooves116 are not particularly limited and may be determined as appropriate depending on theplug frame160 for positioning theferrule110A.
• The materials for the[0128]flange112A may include metallic materials such as stainless steel, brass, and iron. This embodiment uses stainless steel.
• The[0129]plug frame160 includes aferrule insertion hole161 drilled through along the length for theferrule110A and the urgingspring130A to pass through. Theferrule insertion hole161 has aferrule projection hole162 having an inside diameter to project only the ferrulecylindrical member111A.
• The[0130]ferrule insertion hole161 has the twoengaging projections163 therein that engage with thekey grooves116 of theferrule110A so as to project radially inwardly. Theplug frame160 has twoengaging holes164 communicating with theferrule insertion hole161 and open to the outer periphery. Theplug frame160 has an engagingprojection165 projecting radially outward from the outer periphery thereof.
• The[0131]stop ring120A that is fitted to the rear end of theplug frame160 is made of a cylindrical metal having a penetrated optical-fiber-core insertion hole121A that allows the optical-fiber core wire2 to pass through. The optical-fiber-core insertion hole121A has acommunication hole122A at the end for the urgingspring130A to pass through. The difference in the inside diameter between the optical-fiber-core insertion hole121A and thecommunication hole122A provides astep123A.
• The[0132]communication hole122A holds the urgingspring130A therein, into which the rear end of theflange112A of theferrule110A is inserted. When one end of the urgingspring130A comes into contact with the rear end of theflange part115A and the other end comes into contact with thestep123A of thestop ring120A, theferrule110A is urged to and held at the end of theplug housing140A while being urged toward the end with respect to theplug frame160, with the movement toward the end restricted. Thekey grooves116 of theflange part115A are fitted on the engagingprojections163 of theferrule insertion hole161, as described above, and thus theferrule110A is held, with the rotational movement around the axis restricted.
• The[0133]stop ring120A has engagingprojections124A that project in the engagingholes164 of theplug frame160 around the outer periphery of the end of thestop ring120A. Each engagingprojection124A has a tapered outer periphery of which the outside diameter decreases toward the end and is fixed by engagement with the corresponding engaginghole164 of theplug frame160.
• On the other hand, the[0134]plug housing140A has a shape that allows theplug frame160 to be inserted and has anengaging recess146 that engages with the engagingprojection165 of theplug frame160.
• The[0135]optical connector plug100A has theplug housing140A that has a rectangular cross section, which allows theplug housing140A to be positioned in the rotating direction around the axis of theoptical fiber1 owing to the shape of the outer periphery when theoptical connector plug100A is connected to an optical connector adapter (not shown). Theplug housing140A can be connected to the optical connector adapter by 180-degree turn because of the rectangular cross section. Therefore, aprojection147 provided on the outer periphery of theplug housing140A is brought into engagement with a groove provided in a device, and thus theoptical connector plug100A is positioned to the device in the direction of rotation around the axis of theoptical fiber1.
• In other words, the[0136]predetermined reference direction201 including the axis of theoptical fiber1 of the SCoptical connector plug100A according to the embodiment is determined with the outer periphery of theplug housing140A and theprojection147 as the reference.
• With the[0137]optical connector plug100A, theend face111aof the ferrulecylindrical member111A is polished so that the incliningdirection200 of the polished convex curve coincides with thereference direction201 of theoptical connector plug100A.
• In this embodiment, the direction orthogonal to the direction orthogonal to a plane of the[0138]plug housing140A of theoptical connector plug100A, which has theprojection147, is set as a reference direction.
• A[0139]jig plate40A of the end face polishing machine for polishing theend face111aof theferrule110A of theoptical connector plug100A will now be described. FIG. 11 is a perspective view of thejig plate40A according to the second embodiment; and FIGS. 12A and 12B are a top view and a sectional view of thejig plate40A, respectively.
• As illustrated, the[0140]jig plate40A is provided on the end face polishing machine of the first embodiment for holding the SCoptical connector plug100A and includes ajig plate body50A having a plurality of the optical connector plugs100A and holdingmembers60A for retaining the optical connector plugs100A between them and thejig plate body50A.
• The[0141]jig plate body50A is shaped like a polygonal disk and has holdingparts51A each having an opening with the same shape as that of theplug housing140A of theoptical connector plug100A in the vicinity of the periphery around the circumference and detachably holding theoptical connector plug100A.
• Each holding[0142]part51A has acylindrical tube52A, at the bottom, which is fitted to the end of the ferrulecylindrical member111A. Thetube52A has a throughhole53A in the axial direction for thejig plate body50A to pass through along the thickness. The ferrulecylindrical member111A of theoptical connector plug100A placed between thejig plate body50A and the holdingmember60A is inserted into the throughhole53A and only the end of the ferrulecylindrical member111A projects from the bottom of thejig plate body50A.
• The[0143]tube52A has an outside diameter that can be fitted to the end of theplug housing140A of theoptical connector plug100A. The end of theplug housing140A comes in contact with the bottom of the holdingpart51A, so that the amount of the ferrulecylindrical member111A projecting from the bottom of thejig plate body50A is controlled.
• The holding[0144]part51A and thetube52A are provided at an inclination angle to hold theoptical connector plug100A by thejig plate40A such that the rear end of theoptical connector plug100A is inclined from the center to the periphery, relative to the thickness of thejig plate body50A.
• The holding[0145]members60A for holding theoptical connector plug100A with the holdingpart51A are provided around the periphery of thejig plate body50A, that is, portions corresponding to the holdingparts51A.
• The holding[0146]members60A each include acylindrical column support63 of which one end is fixed to the upper surface of thejig plate body50A so as to be inclined in the same direction as that of the holdingpart51A, a fixingpart64 engaging with thecolumn support63 for urging the rear end of theoptical connector plug100A, and atension spring65 on the outer periphery of thecolumn support63 and between the fixingpart64 and thejig plate body50A.
• The fixing[0147]part64 is shaped like a cylinder and has a throughpart67 having a column-support throughhole66 for thecolumn support63 to pass through and anarm68 which projects radially from the side of the throughpart67 and is engaged with the rear end of theoptical connector plug100A. Thecolumn support63 is passed through the column-support throughhole66, so that the fixingpart64 is held movably in the axial direction of thecolumn support63.
• The[0148]tension spring65 is provided around the outer periphery of thecolumn support63 such that one end is fixed to thejig plate body50A and the other end is fixed to the outer periphery of the fixingpart64, thereby urging the fixingpart64 toward the holdingpart51A of thejig plate body50A.
• The[0149]column support63 has ascrew69 screwed in the side thereof, the head of thescrew69 projecting from the side. The fixingpart64 has arecess67aalong the axis with a predetermined length, the recess corresponding to the projecting head of thescrew69. Engagement of therecess67awith the head of thescrew69 restricts rotational movement of the fixingpart64 around the axis.
• The fixing[0150]part64 is urged by thetension spring65 toward the holdingpart51A of thejig plate body50A, thereby clamping theoptical connector plug100A between thearm68 of the fixingpart64 and the holdingpart51A at a predetermined angle.
• The[0151]optical connector plug100A is retained in such a way that the fixingpart64 is first moved upward in the drawing against the urging force of thetension spring65 to thereby increase the distance between thearm68 and the holdingpart51A, and thereafter the end of theferrule110A is passed through the throughhole53A in thetube52A of thejig plate body50A and the fixingpart64 is urged toward the holdingpart51A by the urging force of thetension spring65, thereby claming theoptical connector plug100A between thearm68 of the fixingpart64 and the bottom of the holdingpart51A. Thus theoptical connector plug100A is held while being urged toward thejig plate body50A by thetension spring65 of the holdingmembers60A. At that time, the end of theferrule110A held by theoptical connector plug100A projects by a predetermined amount through the throughhole53A from the surface opposite to the upper surface of thejig plate body50A to which theoptical connector plug100A is held while being urged.
• The[0152]jig plate40A of this embodiment is also constructed, as in the first embodiment, such that theoptical connector plug100A is fixed by being fitted with the holdingpart51A while correcting the target direction of the inclination of thepolished end face111aof the ferrulecylindrical member111A so as to rotate in the direction opposite to the rotating direction of theplaten25 with respect to the plane including the center of thejig plate body50A and theoptical fiber1 so that the incliningdirection200 of theend face111a, polished in convex curve, of the ferrulecylindrical member111A coincides with thereference direction201 of theoptical connector plug100A. Therefore, the holdingpart51A of thejig plate body50A is arranged en advance so as to hold thereference direction201 of theoptical connector plug100A while correcting it to the direction (target direction) rotated around the axis of theoptical fiber1 in the direction opposite to the rotating direction of theplaten25 with respect to the plane containing the center of thejig plate body50A and the axis of theoptical fiber1.
• Thus even with the structure of the[0153]jig plate40A for holding the SCoptical connector plug100A in which the holdingpart51A is provided to thejig plate body50A at a corrected angle and theoptical connector plug100A is directly clamped between the holdingpart51A and the holdingmember60A, the eccentricity between the center of curvature formed at theend face111aof the ferrulecylindrical member111A and the center of theoptical fiber1 can be decreased as small as 5 μm and the insertion loss when the pair of optical connector plugs100A is oppositely connected with an optical connector adapter can be reduced.
• [Other Embodiments][0154]
• Although the embodiments of the present invention have been described, the basic structure of the jig plate and the end face polishing method is not limited to the above description.[0155]
• For example, in the first embodiment, the[0156]optical connector plug100 held by the holdingmember60 is an LC optical connector plug and, in the second embodiment, theoptical connector plug100A held by thejig plate40A is an SC optical connector plug. The present invention, however, is not limited to that. With either structure of thejig plate40 of the first embodiment and thejig plate40A of the second embodiment, any optical connector plugs of an SC type, an FC type, and MU type, held by a plug housing such that the ferrule can move axially to cause rattle, can reduce eccentricity by the polishing according to the invention.
• For example, the plug housing of the FC optical connector plug is shaped like a cylinder and includes a projecting location key therein. Such an FC optical connector plug is positioned to the optical connector adapter in the rotating direction around the axis of the optical fiber with the location key provided inside the plug housing. Therefore, the reference direction of the FC optical connector plug is determined with the location key as the reference. Thus the predetermined reference direction including the axis of the optical fiber of the optical connector plug may be determined as appropriate depending on the outer shape and the location key for positioning in the rotating direction around the axis of the optical fiber when connected to the optical connector adapter.[0157]
• According to the first embodiment, the holding[0158]member60 corrects thereference direction201 of theoptical connector plug100 by 1.5 degrees with respect to the plane including the center of thejig plate body50 and the axis of theoptical fiber1. However, the invention is not limited to that. For example, it is also possible to provide a plurality of holding members with different correction angles and to replace the holding member as appropriate depending on the rotation angle of theferrule110 relative to theplug housing140 due to the rattle.
• According to the second embodiment, the[0159]jig plate body50A includes the recessed holdingpart51A to hold theoptical connector plug100A between the holdingpart51A and the holdingmember60A. However, the holding part of the jig plate body may include a detachable holding, part capable of holding a detachable optical connector plug, as in the first embodiment. Accordingly, it is also possible to prepare a plurality of holding members corresponding to the shape of the optical connector plugs of SC type, FC type and so on to share the jig plate by the plurality of optical connector plugs.
• According to the invention, the end face of a ferrule can be polished so that the apex of the convex curve of a ferrule cylindrical member and the center of curvature coincide with each other even in the state of the optical connector plug that holds the ferrule cylindrical member. This allows insertion loss to be reduced also during the optical connection between the optical connector plugs.[0160]

Claims (20)

What is claimed is:

1. A jig plate opposed to a rotating and fluctuating polishing plate of an end face polishing machine for polishing the end face of a ferrule cylindrical member that holds the tip of an optical fiber, for polishing the face of the ferrule cylindrical member into a convex curve inclined with respect to a plane perpendicular to the axis, with the ferrule cylindrical member brought into contact with the polishing plate at a predetermined angle, comprising:

a jig plate body having a part for mounting to the end face polishing machine; and

a holding part provided to the jig plate body for detachably holding an optical connector plug, the holding part holding the optical connector plug while correcting the target inclining direction of the polished convex curve of the ferrule cylindrical member so as to turn to a direction opposite to the rotating direction of the polishing plate with respect to a plane including the center of the jig plate body and the axis of the optical fiber so that the inclining direction of the polished convex curve of the ferrule. cylindrical member held by the optical connector plug coincides with the reference direction of the optical connector plug.

2. A jig plate according toclaim 1, wherein the reference direction of the optical connector plug is determined with the outer periphery of the optical connector plug as the reference.

3. A jig plate according toclaim 1, wherein the reference direction of the optical connector plug is determined depending on the direction of a location key provided to the optical connector plug.

4. A jig plate according toclaim 1, wherein the holding part of the jig plate body holds the optical connector plug through a holding member for detachably holding the optical connector plug.

5. A jig plate according toclaim 2, wherein the holding part of the jig plate body holds the optical connector plug through a holding member for detachably holding the optical connector plug.

6. A jig plate according toclaim 3, wherein the holding part of the jig plate body holds the optical connector plug through a holding member for detachably holding the optical connector plug.

7. A jig plate according toclaim 4, wherein the holding member can be replaced with a holding member of a different correction angle.

8. A jig plate according toclaim 5, wherein the holding member can be replaced with a holding member of a different correction angle.

9. A jig plate according toclaim 6, wherein the holding member can be replaced with a holding member of a different correction angle.

10. A jig plate according toclaim 1, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into-contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

11. A jig plate according toclaim 2, wherein the optical, connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

12. A jig plate according toclaim 3, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

13. A jig plate according toclaim 4, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

14. A jig plate according toclaim 5, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

15. A jig plate according toclaim 6, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

16. A jig plate according toclaim 6, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

17. A jig plate according toclaim 7, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

18. A jig plate according toclaim 8, wherein the optical connector plug is held such that the ferrule cylindrical member is brought into contact with a polishing surface of the polishing plate relatively at an angle so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

19. An end face polishing method, wherein a ferrule cylindrical member is brought into contact with a polishing member at a predetermined angle with a jig plate, the polishing member being placed on a rotating and fluctuating polishing plate supported by a polishing machine body and the jig plate fixing an optical connector plug having the ferrule cylindrical member holding an optical fiber; and the face of the ferrule cylindrical member is polished into a convex curve inclined with respect to a plane perpendicular to the axis;

wherein the target inclining direction of the polished convex curve of the ferrule cylindrical member is corrected so as to turn to a direction opposite to the rotating direction of the polishing plate with respect to the plane including the center of the jig plate body and the axis of the optical fiber so that the inclining direction of the polished convex curve of the ferrule cylindrical member held by the optical connector plug coincides with the reference direction of the optical connector plug.

20. An end face polishing method according toclaim 19, wherein the ferrule cylindrical member is brought into contact with a polishing surface of the polishing member relatively at an angle and is polished so that the angle formed by the axial direction and a polishing surface closer to the rotation center than the ferrule cylindrical member becomes an obtuse angle.

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