Abstract:
The present invention provides An optical module to be put into a host board, comprising: a module body to be installed on the host board; a projection provided on the module body and adapted to engage with a hook provided in the host board; and a lever mounted on the module body in order to disengage the hook engaging with the projection, to release engagement therebetween, wherein said lever comprises: a first portion which moves when a force is applied thereon in a direction toward the module body; and a second portion for pushing up said hook, said second portion having a tip portion and being interconnected to the first portion, wherein the second portion of the lever is bent toward a direction apart from the module body at a center thereof and bent toward a direction close to the module body at thed tip portion thereof.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 10/342,317, filed on Jan. 15, 2003 now U.S. Pat. No. 6,922,516, which claims the benefit of Japanese Patent Application No. 2002-006242, filed on Jan. 15, 2002, Japanese Patent Application No. 2002-182091, filed on Jun. 21, 2002 and Japanese Patent Application No. 2002-231919, filed on Aug. 8, 2002, the relevance of which is incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hot-plug type optical module. 
     2. Related Background Art 
     An optical module of the pluggable type, which is used in such a manner that the optical module loading with a light emitting unit and/or a light receiving unit is installed in a host board, was known in the prior art. This optical module is generally fixed to the host board, as shown in  FIG. 17A  and  FIG. 17B , through engagement between a hook  41  provided in the host board and a projection  15  provided in a housing  14  of the optical module. The optical module thus fixed is dismounted in the following manner from the host board. In the first step, as shown in  FIGS. 17A and 17B , a wedge-shaped projection  50  is slid along a direction of an arrow to be pushed against the hook  41 . This results in lifting the hook  41  up along a slant surface of the projection  50 , whereby the hook  41  is disengaged from the projection  15 . While the hook  41  is kept in a dismounted state, the optical module is then drawn out of the host board. 
     However, the mechanism for dismounting the optical module, described above, had the problem of poor workability. Namely, in order to disengage the hook  41 , the projection  50  had to be slid to in the pushing direction of the optical module on the occasion of pulling the optical module out of the host board, which was an inefficient work. Particularly, optical modules are mounted in an integrated form on the host board in many cases, and work space is limited. It was thus difficult to draw the optical module while pushing the projection  50  toward the hook  41 . 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide an optical module to be readily disengaged with the host board. 
     According to one aspect of the present invention, an optical module is provided, which is put on a host board. The optical module includes a module body, a projection and a lever. The module body is installed on the host board. The projection is provided on the module body in order to engage with a hook that is provided in the host board. The lever, which is mounted on the module body to disengage the hook, may include a first portion and a second portion. The first portion approaches the module body when a force is applied to the first portion in a direction toward the module body. The second portion, which has a tip portion and is interconnected to the first portion, pushes up the hook. The second portion, according to the present invention, is bent toward a direction apart from the module body a center of the second portion and bent again toward a direction close to the module body at the tip portion thereof. 
     The lever may include a curled portion that connects the first portion to the second portion. The curled portion applies a restoring force to the second portion against the first portion. 
     According to another aspect of the present invention, an optical module that is to be put on a host board and includes a module body, a projection and a lever is provided. The module body is to be installed on the host board. The projection is provided on the module body in order to engage with a hook provided in the host board. The lever, which is mounted on the module body to disengage the hook, may include a first portion and a second portion. The first portion approaches the module body when a force is applied thereto in a direction toward the module body. The second portion, which has a tip portion and is interconnected to the first portion, pushes up the hook. The tip portion, according to the present aspect, has a chamfered edge in a side opposite to the module body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an optical module according to an embodiment and a host board to receive the optical module. 
         FIG. 2  is an exploded perspective view of an optical module. 
         FIG. 3  is a diagram for explaining the principle of releasing the engagement by the lever. 
         FIG. 4  is a perspective view showing the lever according to the first embodiment. 
         FIG. 5  is a perspective view showing the lever according to the first embodiment. 
         FIG. 6  is a perspective view showing part of the housing according to the first embodiment. 
         FIG. 7  is a diagram showing the principle of mounting the lever according to the first embodiment. 
         FIG. 8  is a diagram to explain the role of error-preventing pawls. 
         FIG. 9  is a perspective view showing the optical module according to the second embodiment. 
         FIG. 10  is a perspective view showing the lever according to the second embodiment. 
         FIG. 11A  is a diagram showing the manner of rotation of the actuating member. 
         FIG. 11B  is a diagram showing the manner of rotation of the actuating member. 
         FIG. 12A  is a diagram to explain the mechanism of pivotally moving the lever by the actuating member. 
         FIG. 12B  is a diagram to explain the mechanism of pivotally moving the lever by the actuating member. 
         FIG. 12C  is a diagram to explain the mechanism of pivotally moving the lever by the actuating member. 
         FIG. 13  is a diagram to explain the projections formed in the first portion of the lever. 
         FIG. 14A  is a diagram to explain the angle of rotation of the actuating member on the occasion of releasing the engagement between the projection and the hook. 
         FIG. 14B  is a diagram to explain the angle of rotation of the actuating member on the occasion of releasing the engagement between the projection and the hook. 
         FIG. 15A  is a diagram to explain the angle of rotation of the actuating member on the occasion of releasing the engagement between the projection and the hook. 
         FIG. 15B  is a diagram to explain the angle of rotation of the actuating member on the occasion of releasing the engagement between the projection and the hook. 
         FIG. 16A  shows a conventional type tip shape of the lever. 
         FIG. 16B  shows a tip shape of the lever according to the present invention. 
         FIG. 17A  is a diagram showing the conventional mechanism of releasing the engagement between the projection and the hook. 
         FIG. 17B  is a diagram showing the conventional mechanism of releasing the engagement between the projection and the hook. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the optical module according to the present invention will be described below in detail with reference to the drawings. The same reference symbols will denote the same elements throughout the description of the drawings and redundant description will be omitted. 
       FIG. 1  is a perspective view showing the optical module  10  according to an embodiment and the host board  40  into which the optical module  10  is to be installed, and  FIG. 2  an exploded perspective view of the optical module  10 . As shown in  FIG. 1 , the optical module  10  is inserted into a cage  42  provided in the host board  40 . A projection (blocked from view in  FIG. 1 ) formed in the housing  14  of the optical module  10  then goes into engagement with the hook  41  provided in the host board  40 , whereby the optical module  10  is fixed to the host board  40 . The manner of the engagement between the projection and the hook  41  is the same as the manner of the engagement shown in  FIGS. 28A and 28B . 
     The optical module  10  according to the embodiment will be described below.  FIG. 2  is a view of the optical module  10  from an obliquely lower direction in  FIG. 1 . As shown in  FIG. 2 , the optical module  10  has a light emitting unit  12 , a light receiving unit  11 , a circuit board  13  loaded with circuits for operating the light emitting unit  12  and the light receiving unit  11  (which will be referred to together as “optical unit”), and a housing  14  for housing the optical unit and the circuit board  13 . The circuit board  13  housed in the housing  14  is supported by a board support  16 . The projection  15  to engage with the hook  41  is formed in the housing  14 , and a lever  20  is mounted near the projection  15 . Although the present example describes the optical transceiver module having the light emitting unit  12  and light receiving unit  11 , the module can be a light emitting module having a light emitting unit or a plurality of light emitting units, or a light receiving module having a light receiving unit or a plurality of light receiving units. The number of light emitting unit  12  and light receiving unit  11  in the optical module  10  is not limited to two, but may be four or more. 
     The lever  20  for disengaging the hook  41  from the projection  15  will be described below. The mechanism of releasing the engagement between the projection  15  and the hook  41  by the lever  20  will be first described with reference to  FIG. 3 .  FIG. 3  is a diagram for explaining this mechanism, from which the elements other than the elements necessary for the description are omitted. When the optical module  10  is fixed to the host board  40 , as shown in  FIG. 3 , the hook  41  of the host board  40  engages with the projection  15  formed in the housing. The lever  20  makes use of the mechanism of lever action in order to lift the hook  41  up, and has a fulcrum C, a power point A where a force is affected, and a point of application B for lifting the hook  41  up. As the power point A moves toward the housing  14  with the force on the power point A, the point of application B moves in a leaving direction from the housing  14  with the movement of the power point A, so as to lift the hook  41  up. Without any force on the power point A, the restoring device D keeps the point of application B of the lever  20  located nearer to the housing  14  than the top portion of the projection  15 , so that the lever  20  can be prevented from obstructing the engagement between the projection  15  and the hook  41  in setting the optical module  10  into the host board  40 . The above describes the mechanism of the lever  20  for releasing the engagement in the present invention. 
     The lever  20  according to the embodiment will be described below.  FIG. 4  is a perspective view showing the lever  20  according to the first embodiment. The lever  20  includes a platelike part  21 , which has a first portion  21 A as a power point and a second portion  21 B as a point of application at its both ends, and a mounting part  23 , which is formed by bending the platelike part  21 . The lever  20  is made of metal with excellent mechanical properties, and the platelike part  21  and mounting part  23  are integrally formed. A curled part  22 , which connects the mounting part  23  to the platelike part  21 , functions as a fulcrum.  FIG. 5  is a perspective view of the lever  20  from the side of optical module  10 , in which each side of the mounting part  23  is bent at two positions to form bent portions  23   a ,  23   b  and in which the amount of the bend increases from the curled part  22  toward the free end. The bent portions  23   a ,  23   b  have a function of fixing the mounting part  23  to the housing  14 . Grooves  14   a  for mounting of the lever  20  are formed in a portion of the housing  14  to which the lever  20  is mounted, as shown in  FIG. 6 . Supposing the maximum of the height of the bent portions  23   a ,  23   b  is h, the width of the grooves  14   a  is designed to a value (h−Δh) a little smaller than h. Notches  14   b  formed at an edge of the housing  14  are intended for allowing error-preventing pawls  24  to enter an optical connector receiving area. The fixing of the mounting part  23  into the grooves  14   a  will be described below with reference to  FIG. 7 .  FIG. 7  is a diagram showing the relation between the bent portions  23   a ,  23   b  of the mounting part  23  and the grooves  14   a . Inserting the mounting part  23  into the grooves  14   a , the mounting part is inserted from the smaller bend amount side and thus the mounting part  23  smoothly moves into the grooves  14   a . Once the mounting part  23  is inserted into the grooves  14   a , the bent portions  23   a ,  23   b  will catch in the grooves if one tries to move the mounting part  23  backward (in the dismounting direction). The mounting part is efficiently fitted into the grooves  14   a  in this way, whereby the lever  20  is fixed to the housing  14 . 
     Referring again to  FIG. 5 , the first portion  21 A is provided with the error-preventing pawls  24  extending toward the mounting part  23 . The error-preventing pawls  24  have a function of preventing the optical module  10  from being dismounted from the host board  40  during an optical connector being inserted therein. The function of the error-preventing pawls  24  will be described with reference to  FIG. 8 .  FIG. 8  is a view of the housing  14  and the lever  20  mounted on the housing  14  from the side of the optical module  10 . The elements other than those necessary for the description of the function of the error-preventing pawls  24  are omitted from  FIG. 8 . The housing  14  is cut away on the fixing side of the lever  20  (cf.  FIG. 6 ), so as to communicate with the connector-receiving area. The error-preventing pawls  24  are allowed to go into the connector-receiving area through the notches  14   b . In  FIG. 8 , a dashed line indicates the position of the lever  20  with a force on the first portion  21 A when the optical connector is not received. When the force is applied on the first portion  21 A in the state when the optical connector  18  is not received, the first portion  21 A moves toward the housing  14 , as indicated by the dashed line in  FIG. 8 , and with this movement the second portion  21 B moves in the leaving direction to disengage the hook  41  from the projection  15 . When the optical connector  18  is received in the connector-receiving area, however, the error-preventing pawls  24  go into contact with the optical connector with the movement of the first portion  21 A toward the housing  14 , as shown in  FIG. 8 , so that the movement of the first portion  21 A is restricted at the point of the contact between the error-preventing pawls  24  and the optical connector. This also results in restricting the movement of the second portion  21 B, whereby the hook  41  is incapable of being disengaged from the projection  15 . The length of the error-preventing pawls  24  can be set to a length enough to restrict the movement of the first portion  21 A so as to prevent the second portion  21 B from disengaging the hook  41 . More specifically, supposing the hook  41  is disengaged when the lever  20  is located at the position indicated by the dashed line in  FIG. 8  with the movement of the first portion  21 A by Δx, the length of the error-preventing pawls  24  is determined so that the amount of displacement of the first portion  21 A becomes smaller than Δx. 
     The function of the optical module  10  according to the first embodiment will be described below. The optical module  10  according to the first embodiment is provided with the lever  20  having the first portion  21 A and the second portion  21 B. The optical module  10  is configured so that the second portion  15  moves away from the housing  14  with movement of the first portion  21 A toward the housing  14 . Therefore, for pulling the optical module  10  out the host board  40 , the user pinches the first portion  21 A of the lever  20  whereupon the hook  41  engaging with the projection  15  is disengaged by the second portion  21 B, to whereby the optical module  10  is smoothly dismounted from the host board  40 . 
     Since the first portion  21 A of the lever  20  is provided with the error-preventing pawls  24  extending to the area for reception of the optical connector  18 , the motion of the lever  20  is restricted when the optical connector  18  is inserted in the optical module  10 . This prevents the hook  41  from being accidentally disengaged from the projection  15  during the operation of the optical module  10 . Since the mechanism of dismounting the optical module  10  of the conventional slide type actuator with no means for restricting the longitudinal motion, the optical module  10  was accidentally dismounted during the operation of the optical module  10 . The optical module  10  according to the embodiment also has permitted control in this respect. 
     The optical module  60  according to the second embodiment of the present invention will be described next.  FIG. 9  is a perspective view of the optical module  60  according to the second embodiment, viewed from the lever mounting surface side. As shown in  FIG. 12 , the optical module  60  according to the second embodiment has the projection  15  formed in the module body, the lever  70  mounted adjacent to the projection  15 , and an actuating member  80  to move the first portion  71 A of the lever  70  toward the module body. 
     The projection  15  has a function of engaging with the hook provided on the host board. 
       FIG. 10  is a perspective view showing the lever  70 . The lever  70  includes the platelike part  71  having the first portion  71 A as a power point and the second portion  71 B as a point of application, and the mounting part  73  formed by bending part of the platelike part  71 . The lever  70  is made of metal with excellent mechanical properties, and the platelike part  71  and mounting part  73  are formed integrally. The curled part  72 , which connects the mounting part  73  to the platelike part  71 , serves as a fulcrum. The mounting part  73  is bent at two positions to form actuator-supporting parts  74  rotatably supporting an axis part  80   b  of the actuating member  80 . The first portion  71 A extends nearly in parallel with the mounting part  73  and the distal end thereof is rounded in the direction away from the mounting part  73 . The first portion  71 A is formed so as to be located nearer to the mounting part  73  than the axis part  80   b  which will be set through the actuator-supporting parts  74 . 
     The actuating member  80 , as shown in  FIG. 9 , is an annular shaped member surrounding an optical connector insertion slot and having the shape almost along the edge of the end face of the optical module  60 . A portion of the actuating member  80  along the edge of the lever mounting surface constitutes the axis part  80   b . A grip part  80   c  is formed in a portion of the actuating member  80  along the edge of the surface opposed to the lever mounting surface. A sliding contact part  80   a  projecting in the insertion direction of the optical connector is formed near the central region of the axis part  80   b . The actuating member  80  is rotatably mounted on the lever  70  while the axis part  80   b  thereof is set through the actuator-supporting parts  74  of the mounting part  73 . The axis part  80   b  is supported at two positions on the both sides of the sliding contact part  80   a  by the actuator-supporting parts  74  of the lever  70 . The actuating member  80  is mounted on the lever  70  in the present embodiment, whereas the actuating member  80  may be mounted on the module body. 
     The rotation of the actuating member  80  will be described below with reference to  FIGS. 11A and 11B .  FIG. 11A  and  FIG. 11B  are perspective views of the optical module  60  viewed from the side of the surface opposite to the lever mounting surface. For inserting the optical connector, as shown in  FIG. 11A , the actuating member  80  is set to adjoin the optical connector insertion slot so as to clear the space in front of the optical connector insertion slot. For dismounting the optical module  60  from the host board, the actuating member  80  is rotated to locate the grip part  80   c  on the same plane as the lever mounting surface, as shown in  FIG. 11B . In the description hereinafter, the position of the actuating member  80  shown in  FIG. 11A  will be referred to as “first position,” and the position of the actuating member  80  shown in  FIG. 11B  as “second position.” 
     Subsequently, the operation of the actuating member  80  and lever  70  will be described with reference to  FIGS. 12A and 12B . With the lever at the first position, as shown in  FIG. 12A , the lever  70  is located by the restoring force of the curled part  72  so that the second portion  71 B is lower than the top portion of the projection  15  (on the module body side), and the hook not shown is in engagement with the projection  15 . The grip part  80   c  of the actuating member  80  is then moved away from the optical connector insertion slot to rotate the actuating member  80 , whereupon the sliding contact part  80   a  of the actuating member  80  rotates about the axis part  80   b  (counterclockwise in the figure) with the rotation of the actuating member. This motion rotationally moves the sliding contact part  80   a  toward the module body (upward in  FIG. 12B ) and the sliding contact part  80   a  slides on the first portion  71 A of the lever  70 , so as to push the first portion  71 A toward the module body. This pivotally moves the lever  70  about the curled part  72 , so that the second portion  71 B of the lever  70  moves upward, as shown in  FIG. 12B . Then the second portion  71 B pushes up the hook (not shown) engaging with the projection  15 , to disengage the hook from the projection  15 .  FIG. 13  is a partly enlarged view showing an enlarged contact state between the sliding contact part  80   a  and the first portion  71 A. As shown in  FIG. 16 , with the actuating member  80  at the second position, the sliding contact part  80   a  of the actuating member  80  engages with a projection  75   a  formed in the first portion  71 A, so as to restrict the rotation of the actuating member  80  in the direction of arrow A in  FIG. 13 . This prevents the actuating member  80  from returning to the first position because of the restoring force of the lever  70 . When a force over a prescribed level is applied on the grip part  80   c , the sliding contact part  80   a  climbs over the projection  75   a , so that the actuating member  80  can be returned to the first position. The sliding contact part  80   a  of the actuating member also engages with a projection  75   b  formed in the first portion  71 A, so as to restrict rotation of the actuating member  80  in the direction of arrow B in  FIG. 13 . This restricts the rotation of the actuating member  80  with the grip part  80   c  at the second position on the same plane as the lever mounting surface. This makes the user conscious that the optical module can be drawn by pulling the grip part  80   c  at the second position. Furthermore, the sliding contact part  80   a  can climb over the projection  75   b , so that the actuating member  80  can be rotated in the direction opposite to the first position, as shown in  FIG. 15C . This mechanism can prevent the failure such as detachment of the actuating member  80  with application of a downward force on the grip part  80   c  at the position of  FIG. 12B . The first portion  71 A in slide contact with the sliding contact part  80   a  is so curved that the second portion  71 B can be maintained at the position of the top portion of the projection  15  during the rotation of the actuating member  80  up to the state shown in  FIG. 12C . 
     The following will describe the angle of rotation of the actuating member  80  during the disengagement of the hook  41  from the projection  15 .  FIG. 14A  and  FIG. 14B  are diagrams showing positions of the actuating member  80  during the disengagement of the hook  41  from the projection  15 . 
     The actuating member  80  rotates away from the optical connector insertion slot from the state in which the grip part  80   c  is adjacent to the optical connector insertion slot, as described above. In the example shown in  FIG. 14A , before the grip part  80   c  reaches an area R occupied by the optical connector to be inserted, the second portion  71 B moves up to the top portion of the projection  15 , so as to release the engagement between the projection  15  and the hook  41 . The angle of rotation of the actuating member  80  with the grip part  80   c  arriving at the area R can be calculated from the height of the end face of the optical module  60 , the height of the optical connector, and so on. The amount of rotation is 68° in the case of standard optical modules. Therefore, the optical module is designed so that the engagement between the hook  41  and the projection  15  is released at the rotation angle of not more than 68°. In the example shown in  FIG. 14B , when the grip part  80   c  moves into the area R or when it is rotated over the area R, the second portion  71 B moves up to the top portion of the projection  15  to release the engagement between the projection  15  and the hook  41 . In this case, the optical module is designed so that the engagement between the hook  41  and the projection  15  is released at the rotation angle of greater than 68°. In the optical module  60  according to the present embodiment, the rotation angle of the actuating member  80  upon the disengagement can be designed as shown in each of  FIGS. 14A and 14B . The rotation angle of the actuating member  80  can be changed, for example, by a method of changing the angle of the sliding contact part  80   a  relative to the position of the grip part  80   c , by a method of changing the degree of curvature of the first portion  71 A on which the sliding contact part  80   a  slides, etc., as shown in  FIGS. 14A and 14B . 
     The example of releasing the engagement before the grip part  80   c  arrives at the area R (cf.  FIG. 14A ) has the advantage that the hook  41  engaging with the projection  15  can be disengaged in the state in which the optical connector is inserted in the optical module  60 . Normally, an optical connector, when dismounted from the optical module  60 , needs to be cleaned before inserted again, but using of this arrangement permits the optical module  60  to be dismounted from the host board  40  when the optical connector is inserted in the optical module  60 . In this arrangement that the hook  41  is disengaged in the inserted state of the optical connector, the lever is not provided with the pawls  24  for restricting the movement of the first portion  21 A, which were described in the first and the second embodiment. In the example that the engagement is released when the grip part  80   c  moves into the connector occupying area R (cf.  FIG. 14B ) or rotates over the connector occupying area R, the grip part  80   c  goes into contact with the inserted optical connector when the optical connector is inserted in the optical module  60 , so that the optical module  60  cannot be drawn out of the host board  40  in the connector inserted state. Namely, it is feasible to prevent such an accident that the optical module  60  is accidentally slipped off from the host board  40  during the operation in which signal light flows through the optical connector. In the examples of  FIGS. 14A and 14B , the design of actuating member  80  can be determined depending upon environments in which the optical module  60  is used. For example, the actuating member  80  of the error-preventing type as shown in  FIG. 14B  is suitably applicable where the optical module is used in such environments that the optical module  60  must be prevented from being drawn during the operation, like the backbone part. Conversely, the actuating member  80  of the type as shown in  FIG. 14A  to permit insertion into and removal from the host board  40  even in the inserted state of the optical connector is suitably applicable to the case where it is used in such environments that switching is often carried out, for example, like switching portions. 
     Although not illustrated in  FIGS. 14A and 14B , the connector occupying area R stated in the present invention also includes an optical plug for connecting the optical connector to the optical module  60 . Namely, the rotation of the grip part  80   c  can be restricted by decreasing the radius of rotation of the grip part  80   c  as shown in  FIG. 15A  and by letting the grip part  80   c  hit the optical plug halfway of the rotation of the actuating member as shown in  FIG. 15B . This arrangement can prevent the erroneous operation of dropout of the optical connector in the state in which the optical connector is inserted. 
     The optical module is installed on the host board by mating the projection  15  provided in the body of the optical module with the hook  41  on the host board. In the case that the hook  41  mates with the projection  15  as the lever  70  is pushed up and runs onto the hook  41 , the optical model ultimately mates with the host board so far as they are manually released. 
     As shown in  FIG. 16A , the tip of the hook is apart from the module body by about 0.5 mm at most, on the other hand they must be apart greater than 0.5 mm, at least 0.7 mm to release the mating between the hook  41  and the projection  15 . Therefore, the mating the optical module with the host board can be prevented as the lever  70 , in the tip of the second portion  71 B thereof, is onto the hook  41  and the mating therebetween can be successfully released when the lever  70  is under the hook  41 , by configuring the lever such that the tip the second portion  71 B thereof is apart from at most 0.5 mm from the module body and when the lever  70  is under the hook  41 , the top of the second portion  71 B is at least 0.7 mm apart from the module body by rotating the actuating member  80 . 
     In the present invention, the tip of the second portion  71 B, as shown in  FIG. 16B , has such that (1) it is bent inside, (2) a outside corner thereof is chamfered, and the both shapes (1) and (2) are appeared. The lever shown in  FIG. 13  is made of stainless or surface treated iron with a thickness of about 0.4 mm by cutting and bending. The configuration that the second portion  71 B is once bent upward at a center thereof by 0.1 to 0.2 mm and is bend downward at the tip by 0.1 mm to 0.2 mm corresponds to the shape (1) above mentioned. The other configuration that the outside corner of the tip of the second portion  71 B by 0.1 mm to 0.2 mm is chamfered corresponds to the second shape (2). 
     In the arrangement that the optical module has the actuating member including the sliding contact part slidingly contacting the first portion of the lever and being rotatable about the axis part adjacent to the sliding contact part and that the actuating member is rotated to move the first portion of the lever toward the module body, the hook can be readily disengaged by the actuating member and the optical module can be drawn out of the host board even in the case where optical modules are integrated in high density.