Abstract:
This invention relates to an alignment apparatus for aligning a planar optical wave-guide element and an optical fiber block wherein alignment can be completed with more precision and less expense than conventional methods. The alignment apparatus comprising a lower plate; a sliding table mounted on the lower plate capable of horizontal displacement on the lower plate; an upper plate mounted to the sliding table; and, a jig disposed on the upper plate and fixed to rotational means and capable of rotation about the upper plate for holding the optical fiber block.

Description:
CLAIM OF PRIORITY 
   This application claims priority to an application entitled “ALIGNMENT APPARATUS FOR OPTICAL FIBER BLOCKS”, filed in the Korean Intellectual Property Office on Sep. 18, 2002 and assigned Serial No. 2002-56975, the contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical communication device. More particularly, it relates to an alignment apparatus for connecting an optical fiber block to a planar optical wave-guide element. 
   2. Description of the Related Art 
   In general, a planar optical wave-guide element has been used to divide many different wavelengths of optical signals advancing through a single optical path into respective single wavelengths of optical signals advancing through a plurality of optical paths. The planar optical wave-guide element includes at least one input terminal end and a plurality of output terminal ends so as to branch optical signals. There is included a core forming an optical wave-guide path between the input and output terminal ends to branch optical signals. The core is enclosed by a cladding material. Each of the input and output terminal ends is connected by an optical fiber, thus causing optical signals to be input or output. 
   Typically, an optical fiber block is used to stably connect an optical fiber to the input or output terminal end of the planar optical wave-guide element. The optical block is adapted to arrange a single-cored optical fiber or a multiple-cored optical fiber into a V-shaped groove and then bond the optical fiber with an adhesive such as epoxy or the like, wherein the single-cored optical fiber has a single optical fiber strand, without an outer sheath on its terminal end, arranged into the V-shaped groove, but the multiple-cored optical fiber does generally take a ribbon form and has a plurality of optical fiber strands, without an outer sheath on its terminal end, arranged into the V-shaped groove. 
   The optical fibers arranged on the optical fiber block as well as on the planar optical wave-guide element as mentioned above must be connected to each other with considerable precision. 
     FIG. 1  is a perspective view of an alignment apparatus  100  for optical fiber blocks according to a conventional embodiment.  FIG. 2  is a side view for describing the operation of the alignment apparatus  100  for optical fiber blocks shown in  FIG. 1 . As shown in  FIGS. 1 and 2 , an alignment apparatus  100  for optical fiber blocks in accordance with the conventional embodiment is mounted on an alignment driving actuator  190  and comprises a base plate  111 , a lower plate  113 , a upper plate  115 , a sliding table  117 , a jig  119  for locking an optical fiber block, a locking axle  127 , a locking driver  125 , and a displacement sensor  123 . 
   The base plate  111  includes a first plate  111  a for mounting the alignment apparatus  100  for optical fiber blocks to the alignment driving actuator  190 , and a second plate  111   b  extending in a direction perpendicular to the first plate  111   a . The lower plate  113  is mounted to the second plate  111   b.    
   The lower plate  113  helps to guide the sliding table  117  to move horizontally in a forward or backward direction z, taking a folded form vertically extending from the opposite ends thereof so as not only to mount the locking driver  125  but also to restrict a movable range of the sliding table  117 . That is to say, the lower plate  113  is designed so that the movable range of the sliding table  117  is restricted by it and that both the locking driver  125  and the displacement sensor  123  are mounted to it. 
   The sliding table  117  is intended to finely align an optical fiber block  101  which is locked to the jig  119 . When the optical fiber block  101  is locked to the jig  119 , the optical fiber block  101  is subjected to a resilient force from a certain resilient means  121  in a direction such that the optical fiber block  101  comes into a close contact to a corresponding counterpart component  102  such as the planar optical wave-guide element. The sliding table  117  is horizontally movable on the lower plate  113  and at the same time is subjected to restriction to the movable range thereof by the configuration of the lower plate  113 . 
   The upper plate  115  is firmly mounted on the sliding table  117  so that it is possible for the upper plate to move together with the sliding table  117 . The upper plate  115  is also provided with the jig  119 . 
   The jig  119  for locking the optical fiber block  101  includes a bracket  119   a  for positioning the optical fiber block  101  and a holder  119   b  for locking the optical fiber block  101  positioned by the bracket  119   a . The optical fiber block  101  positioned by the bracket  119   b  is locked to protrude forward farther than both the lower plate  113  and the upper plate  115 . 
   The locking axle  127 , the locking driver  125  and the displacement sensor  123  are installed on the folded part  113   a  vertically extending from a rear end of the lower plate  113 . Therefore, the sliding table  117  is locked when displacement of the sliding table  117  aligns the optical fiber block  101  in the optimal position. That is to say, the optical fiber block  101  comes into close contact with the counterpart component, such as a planar optical wave-guide element or the like. An end surface of the optical fiber block  101  is aligned parallel to an end surface of the counterpart component. At this position, the sliding table  117  is located at a forefront while the optical fiber block  101  is aligned, whereby the position is sensed by the displacement sensor  123 . The locking driver  125  moves the locking axle  127  forward, and thereby locks the upper plate  115 . 
   The alignment apparatus  100  for optical fiber blocks as mentioned above is mounted on the alignment driving actuator  190 . 
   The alignment driving actuator  190  provides the optical fiber block  101  with three dimensional linear and rotational alignments in relation with a x-axis, a y-axis and a z-axis, respectively, wherein the linear alignments are performed along to the respective x-, y- and z-axes, i.e. in a left or right direction x, in an upward or downward direction y, and in a forward or backward direction z; whereas the rotational alignments are performed about the respective x-, y- and z-axes, i.e. in a x-axial rotational direction θx, in a y-axial rotational direction θy, and in a z-axial rotational direction θz. 
   Referring to  FIG. 2 , the linear alignments of all the x-, y- and z-axes and the rotational alignment for the z-axis are performed by a lower driving actuator  191 . The rotational alignments of the x- and y-axes are performed by first and second upper driving actuators  197  and  199 . The lower driving actuator  191  first performs an approximate alignment first and then the upper driving actuators  197  and  199  perform a fine alignment. 
   Also, for alignments of the three axial linear directions x, y and z, respectively, and three axial rotational directions θx, θy and θz, driving motors are required corresponding to each of the directions. Particularly, for respective fine alignments of the x and y axial rotational directions θx and θy, respectively, driving motors with high precision are required. 
   Despite these high precision driving motors, the conventional alignment apparatus is flawed in that the motors perform alignment of the x- and y-axial rotational directions, θx and θy respectively, individually, resulting is poor alignment with respect to one another. Moreover, the bracket on which the optical fiber block is positioned is manufactured corresponding to the size of the optical fiber block. Consequently, the bracket should be replaced in order to align another optical fiber block on which another cored optical fiber is arranged. 
   SUMMARY OF THE INVENTION 
   Accordingly, there is a need to provide an alignment apparatus that can perform its intended purpose efficiently with more precision and less expense. 
   According to one aspect of the invention, a jig that freely rotates about the axis running through the center of the fiber optic block is provided and serves as the alignment means about the y rotational axis, and further provides for simultaneous alignment of the x and y rotational axes providing a higher magnitude of precision. The jig eliminates the need for a separate driving motor for the alignment of the y rotational axis reducing the manufacturing cost of the apparatus. 
   According to another aspect of the invention, a jig is provided with a supporting part that traverses on the holding part, thereby permitting the use of fiber optic blocks of different sizes on the same jig and decreasing manufacturing costs as only one jig is needed to perform the alignment for any size of fiber optic block. 
   Accordingly, there is provided an alignment apparatus for optical fiber blocks for aligning a planar optical wave-guide element and an optical fiber block, comprising: a lower plate; a sliding table mounted on the lower plate capable of horizontal displacement on the lower plate; an upper plate mounted to the sliding table; and, a jig disposed on the upper plate and fixed to rotational means capable of rotation about the upper plate for holding the optical fiber block. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a perspective view of an alignment apparatus for optical fiber blocks according to a conventional embodiment; 
       FIG. 2  is a side view for describing operation of the alignment apparatus for optical fiber blocks shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of an alignment apparatus for optical fiber blocks according to a preferred embodiment of the present invention; 
       FIG. 4  is a side view of the alignment apparatus for optical fiber blocks shown in  FIG. 3 ; 
       FIG. 5  is a perspective view showing a state in that a jig is eliminated from the alignment apparatus for optical fiber blocks shown in  FIG. 3 ; 
       FIG. 6  is a perspective view of a jig of the alignment apparatus for optical fiber blocks shown in  FIG. 3 ; 
       FIG. 7  is a perspective view of a bracket of the jig shown in  FIG. 6 ; and, 
       FIG. 8  is a side view for describing operation of the alignment apparatus for optical fiber blocks shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the purposes of clarity and simplicity, a detailed description of known functions and configurations incorporated herein ill be omitted as they would obscure the invention in unnecessary detail. 
     FIG. 3  is a perspective view of an alignment apparatus  200  for optical fiber blocks according to a preferred embodiment of the present invention.  FIG. 4  is a side view of an alignment apparatus  200  for optical fiber blocks as shown in  FIG. 3 . As shown in  FIGS. 3 and 4 , an alignment apparatus  200  for optical fiber blocks according to a preferred embodiment of the present invention comprises a base plate  211 , a lower plate  213 , a sliding table  217 , an upper plate  215 , a jig  219  for locking an optical fiber block, a locking axle  227 , a locking driver  225  and a displacement sensor  223 . The alignment apparatus  200  is mounted on an alignment driving actuator  290 , as shown in  FIG. 8 . 
   The base plate  211  extend vertically upward at one end where it is mounted to the alignment driving actuator  290  of the alignment apparatus  200 . The lower plate  213  is mounted to the base plate  211 . 
   The lower plate  213  acts as a guide for the sliding table  217  to move horizontally thereon in a forward and backward direction z. Both ends of lower plate  213  protrude perpendicularly upward in direction y so that one end serves to mount the locking driver  225 , locking axle  227 , and the displacement sensor  223  therethrough. Another consequence of the lower plate  213  having such a configuration is to restrict the displacement of the sliding table  217  thereon. That is, the vertical ends act as stops or side walls for the sliding table  217 . The upper plate  215  is rigidly mounted on the sliding table  217  so that they are both displaced horizontally simultaneously with respect to the lower plate  213 . The upper plate  215  is constructed having an L-shape. It is fixed to the sliding table  217  so that one portion of the upper plate  215  lays flat on the top surface of the sliding table  217  and the other end is perpendicular to that portion and extends downward in a y direction so as to come between the sliding table  217  on one side and the locking axle  227 , the locking driver  225 , and displacement sensor  223  on the other side. The upper plate  215  is provided with the jig  219  attached thereon. 
   A resilient means  221  for providing a resilient force upon the sliding table  217  is fitted between the side wall of the lower plate  213  having the locking driver  225 , locking axle  227 , and displacement sensor  223  mounted therethrough, and the portion of the upper plate  215  extending downward in a y direction. The resilient force acts on the upper plate in the z direction displacing the upper plate, the sliding table  217 , and the jig  219  in the same direction. Consequently, the optical fiber block  201  which is locked in the jig  219  comes into close contact with a corresponding counterpart component, for example the planar optical wave-guide element. 
   As shown in  FIG. 6 , the jig  219  for locking the optical fiber block includes a bracket  219   a  for positioning the optical fiber block  201  and a holder  219   b  for locking the optical fiber block  201  positioned by the bracket  219   a . The jig  219  is mounted in a horizontal plane on the upper plate  215  so that the jig can rotate in a y-axial rotational direction θy. In one embodiment of this invention as shown in  FIG. 5 , a bearing  231  and a rotation shaft  233  are mounted in the upper plate  215 , as shown in  FIG. 5 . The bearing  231  is press-fitted into the upper plate  215 . The rotation shaft  233  is rotatably connected to the bearing  231  extending axially through the upper plate  215 . The rotation shaft  233  protrudes above the upper plate  215 . The jig  219  is mounted on the protruded end of the rotation shaft  233 . This feature eliminates the need for a precision driving motor to align the jig  219  about the y axis. The optical fiber block  201  is preferably locked on the bracket  219   a  in a state such that the optical fiber block extends beyond the lower and upper plates  213  and  215 . 
   In another embodiment of this invention as shown in  FIG. 7 , the bracket  219   a  comprises a locking part  21  and a supporting part  23 . The locking part  21  provides a surface upon which the optical fiber block  201  is placed, while the supporting part  23  supports one end of the optical fiber block  201 . The size of an optical fiber block  201  varies depending on the number of optical fiber strand arranged on the optical fiber block  201 . Consequently, since the size of different optical fiber blocks  201  may vary, the supporting part  23  may shift its horizontal position on the locking part  21  accordingly to accommodate a range of sizes of optical fiber blocks  201 . This feature results in using one bracket  219   a  for a range of optical fiber blocks  201  of different sizes. This eliminates the disadvantage of a conventional alignment apparatus for optical fiber blocks wherein the bracket must be replaced every time an optical fiber block of a different size is to be aligned. 
   Describing the operation of the components of the alignment apparatus  200  for optical fiber blocks according to the embodiments of this invention, the resilient force applied by the resilient means  221  is applied against the portion of the upper plate  215  extending perpendicular to it. This force results in the linear displacement of the upper plate  215 . As the upper plate  215  is fixed to the jig by means of the rotation shaft  233 , the jig  219  is also displaced by the same magnitude in the z horizontal direction. The displacement of the upper plate  215  and jig  219  are restricted in all other linear directions due to the fact that the upper plate  215  is rigidly fixed to the sliding table which is constrained to displacement only in the linear z direction. As these components are displaced, the optical fiber block  201  loaded in the jig comes into close contact with the corresponding counterpart component, such as the planar optical wave-guide element. An end surface of the optical fiber block  101  is aligned parallel to an end surface of the counterpart component. There, the sliding table  217  is at maximum displacement. As the optical fiber block  201  comes into close contact with the counterpart component, the jig  219  pivots about the rotation shaft  233  aligning itself automatically. The optical fiber block  201  is aligned in the optimal position when the sliding table  217  is displaced to its maximum extent. Thereafter, the displacement sensor  223  senses this maximum displacement generating a signal causing the locking driver  225  to drive the locking axle  227  to lock the upper plate  215  in its current position. Consequently, the jig  219  is also prevented from further linear displacement thus preventing any further rotation about the rotation shaft  233 . 
   In another embodiment of this invention, the jig  219  may be provided with a spherical member  229  positioned so that it comes into contact with the locking axle  227  when the locking driver  225  drives the locking axle  227  forward to lock the jig  219  in the optimum position. This spherical member  229  is to uniformly distribute a locking force upon the jig  219  when one end of the locking axle  227  comes into contact with it. In one embodiment of this invention and as shown in  FIG. 5 , two vertical pegs  240  extending vertically upwards in a y direction formed on the top surface of the top plate form the rotational limits that the jig  219  may rotate about the y axis. These pegs limit the rotation and act as stops for the jig  219  when the spherical member  229  come into contact with them. This assures that the spherical member  229  does not rotate outside the range where the locking axle  227  may come into contact with it when it is driven by the locking driver  225 . 
   The alignment apparatus  200  for optical fiber blocks as described in the invention is mounted on the alignment driving actuator  290  that enables the jig  219  to pivot about a y rotational axis θy, so that the alignment apparatus does not require a separate driving motor for alignment in the y rotational axis θy, unlike the conventional alignment apparatus. 
   The alignment driving actuator  290  requires three dimensional linear and rotational alignments in relation with a x-axis, a y-axis and a z-axis, respectively, where the linear alignments are performed along to the respective x-, y- and z-axes, i.e. in a left or right direction x, in an upward or downward direction y, and in a forward or backward direction z; whereas the rotational alignments are performed about the respective x-, y- and z-axes, i.e. about a x rotational axis θx, about a y rotational axis θy, and about a z rotational axis θz. The linear alignments in all the x-, y- and z-axes and the rotational alignment about the z rotational axis are performed by a lower driving actuator  291 , and the rotational alignments to the x-axis is performed by an upper driving actuator  299 . 
   To align the optical fiber block using the alignment apparatus  200 , the lower driving actuator  291  performs an approximate alignment first and then the upper driving actuator  299  performs a fine alignment. The alignment about the y rotational axis θy is automatically performed at the moment when the optical fiber block  201  contacts the counterpart component and the jig  219  rotates about the rotation shaft  233 . 
   Opposingly, in the conventional alignment apparatus for optical fiber blocks  100 , the y axis of rotation θy is located on the rear side of the base plate  111  (see  FIG. 1 ) and is spaced apart from the optical fiber block to a certain extent. Therefore, even a fine operation of the driving motor about the x rotational axis θx results in an increasing displacement of the optical fiber block because of the distance between the y axis of rotation θy and the optical fiber block. The conventional apparatus thus requires the driving motor to be operated with high precision. 
   To the contrary, the alignment apparatus  200  for optical fiber blocks of this invention provides a y axis of rotation θy located through the position where the optical fiber block  201  is locked. This occurs due to the axis of the rotational shaft  233  that the jig  233  rotates about being located through the c enter of the optical fiber block  201  locked position. Therefore, it is easy to adjust a displacement of the optical fiber block  201  finely during the alignment of the optical fiber block. Moreover, it is possible to simultaneously perform the alignment about the y and x axes of rotation, θy and θx, because as a resilient force is applied in a direction in which the optical fiber block  201  contacts the counterpart component, the rotation shaft  233  and bearing  231  provide a rotational means for the jig. 
   In the embodiments of the present invention as shown in  FIG. 8 , the following is a description of the procedure for aligning an optical fiber block using the alignment apparatus  200  for optical fiber blocks. The optical fiber block  201  is positioned on the alignment apparatus  200 , wherein the alignment apparatus  200  is mounted on the alignment driving actuator  290 . Here, the bracket  219   a  is adjusted to accommodate the size of the optical fiber block  201 . When the optical fiber block  201  is positioned, the lower driving actuator  291  is operated to perform linear alignments initially for the x- and y-axial directions and the rotational alignment about the z rotational axis and then to advance the alignment apparatus  200  toward the counterpart component  202 , such as the planar wave-guide element, in the z-axial direction. 
   When the alignment apparatus  200  advances coming into contact with the optical fiber block  201 , the lower driving actuator  291  causes the optical fiber block  201  to advance to a predetermined extent. As the optical fiber block  201  makes contact with the counterpart component, the resulting reaction force of the counterpart component  202  forces the jig  219 , upper plate  215 , and sliding table  217  in the opposite linear z direction relative to the displacement of the alignment apparatus  200 . It will be apparent that advancement of the alignment apparatus  200  by the lower driving actuator  291  should be limited to a displacement no greater than the maximum traveling range of the sliding table  217  on the lower plate  213  once the optical fiber block  201  makes contact with the counterpart component  202 . As the sliding table  217 , upper plate  215 , and jig  219  move in the opposite direction relative to the movement of the alignment apparatus  200 , a resilient force from the resilient means  221  acts upon the upper plate  215  and ultimately the jig  219  and the sliding table  217  as well. The reaction of the forces acting between the optical fiber block  201  and the counterpart component  202  causes the jig  219  to rotate about the y rotational axis θy. The jig  219  continues to rotate freely from the point when the optical fiber block  201  comes into contact with the counterpart component  202  until the point when the alignment is completed. 
   After the alignment apparatus  200  is advanced to a proper position, the alignment about the x rotational axis θx is performed by the upper driving actuator  299 . At this point, the jig  219  also continues to rotate freely about the y rotational axis θy. This configuration efficiently provides for the precise and simultaneous alignment about both x and y axes rotational axes, θx and θy, without the need for an independent driving motor for alignment about the y axis of rotation. At such time when the optical fiber block  201  makes contact with the counterpart component, the displacement sensor  223  senses the position where the sliding table  217  is advanced to a maximum displacement. At such time the alignment of the optical fiber block  201  is complete and the locking driver  225  causes the locking axle  227  to be advanced. In one embodiment of this invention the locking axle  227  advances and makes contact with the upper plate  215  preventing any further linear movement of the upper plate  215 , sliding table  217 , and jig  219 . This also restricts the jig  219  from any further rotation about rotational shaft  233 . In another embodiment the locking axle  227  advances towards the spherical member  229  provided with the jig  219 . Once contact is made the spherical member locks the jig  219  in place preventing it from further advancement or rotation and also preventing further advancement of the upper plate  215  and sliding table  217 . 
   While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.