Abstract:
A light blocking device for an optical transmitter includes a flap ( 46 ) that is movable to a first position in which light is allowed to pass unhindered from a laser ( 18 ), and is movable to a second position to block the light emitted from the laser. The light blocking device further includes a panel member ( 48 ) connectable to a housing ( 10 ) of the optical transmitter. The flap ( 46 ) is connected to an edge of the panel member ( 48 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The subject matter of this application is related to the disclosures contained within U.S. patent application Ser. No. ______, attorney docket no. ROC920010219US1-IBM-213, entitled Integrated Optical Coupler and Housing Arrangement, and filed on Oct. 5, 2001; within U.S. patent application Ser. No. 09/894,934, attorney docket no. ROC920010154US1-IBM-212, entitled Enhanced Optical Transceiver Arrangement, and filed on Jun. 28, 2001; within U.S. patent application Ser. No. 09/894,714, attorney docket no. ROC920010151US1-IBM-210, entitled Enhanced Optical Coupler, and filed on Jun. 28, 2001; and within U.S. patent application Ser. No. 09/893,812, attorney docket no. ROC92001118US1, entitled A Processing Protective Plug Insert for Optical Modules, and filed on Jun. 28, 2001, all having been assigned to International Business Machines, Corporation. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a device for blocking emitted light, and in particular, to an opaque flap that covers a fiber optic cable opening of an optical transmitter when a fiber optic cable is not present within the opening, to prevent light from being emitted from the optical transmitter into the environment.  
           [0004]    2. Background Information  
           [0005]    Computer and communication systems are now being developed in which optical devices, such as fiber optic cables, are used as a conduit (also known as a wave guide) for modulated light waves to transmit information. These systems typically include an optical transmitter that has a light emitter, or an optical receiver that has a light detector. A typical light emitter may be a laser, such as a vertical cavity surface emitting laser (VCSEL). A typical light detector may be a photodiode. A generic term of either an optical transmitter or a optical receiver is an “optoelectronic transducer.” The fiber optic cable is typically coupled to the respective light detector or light emitter, so that optical signals can be transmitted back and forth, for example.  
           [0006]    As an example, optoelectronic transducers convert electrical signals to or from the optical signals; the optical signals carry data to the light detector from the light emitter via the fiber optic cable at very high speeds. Typically, the optical signals are converted into, or converted from, the associated electrical signals using known circuitry. Such optoelectronic transducers are often used in devices, such as computers, in which data must be transmitted at high rates of speed.  
           [0007]    In order to provide for higher speed signal transmissions (for instance 1 Gb/s), the light emitter, for example the laser, needs to be operated at a higher power. This can be accomplished by coupling the laser to a laser driver, and then delivering a relatively high voltage to the laser.  
           [0008]    However, there are environmental and safety concerns that prohibit operating the laser at any selected power. For example, if there is a possibility that the laser light may be transmitted into the ambient environment, it must be ensured that the transmitted light will not cause an injury, if for example, the light should impinge on an eye of a user or passerby. To help reduce the chance of such injury occurring, the Center for Devices and Radiological Health (CDRH) has provided laser safety limits, which stipulate a maximum power a laser may be operated at. Generally, the greater the risk that the laser light may be transmitted into the ambient environment, the lower the laser safety limits are.  
           [0009]    With the conventional laser light emitter, should the fiber optic cable inadvertently become disconnected from the light emitter while in operation, there is a high risk that the laser light will be emitted into the ambient environment. Thus, the laser safety limits for the conventional laser light emitter are relatively low. These low safety limits significantly impede the development of optoelectronic transducers having a very high speed.  
           [0010]    Nevertheless, developers have been able to exceed the CDRH laser safety limits by applying for variances. Although variances are often granted, there are still several concerns. For example, there is some uncertainty by the developers and manufacturers of the optoelectronic transducers as to whether a variance will ultimately be granted. The risk and uncertainty of whether the variance will be granted increases as the output power requirements of the light emitter exceeds the safety limits. That is, it is more likely that a variance will not be granted for a laser light emitter that significantly exceeds the safety limits than for a laser that only slightly exceeds the safety limits. Moreover, applying for a variance is time consuming, and may impede the development process. Furthermore, if the variance is not granted, then the optoelectronic transducer will need to be redesigned using a lower power. Additionally, even if the variance is granted, there is a possibility that the light emitter will be prohibited from being used or sold in foreign countries, for exceeding the foreign country&#39;s own safety limits. Moreover, the granting of a variance does not reduce the risk of injury to a user or passerby, should the fiber optic cable inadvertently become disconnected from the light emitter while in operation. To the contrary, the risk of injury is increased, since the power of the light emitter will be exceeding the designated safety limits.  
           [0011]    Thus, there is a need for an optoelectronic transducer that can be operated at a high power output without requiring safety limit variances. There is a further need for an optoelectronic transducer that can be safely operated at any desired power level. Further, there is a need for a safety device that can be used on a conventional optoelectronic transducer, that allows the optoelectronic transducer to be safely operated at any desired power level, and without applying for a safety limit variance.  
         SUMMARY OF THE INVENTION  
         [0012]    It is, therefore, a principal object of this invention to provide a device for blocking emitted light.  
           [0013]    It is another object of the invention to provide a device for blocking emitted light that solves the above mentioned problems.  
           [0014]    These and other objects of the present invention are accomplished by the device for blocking emitted light disclosed herein.  
           [0015]    According to one aspect of the invention, a device is provided that can be used with a light emitter, such as those used within optical transmitters, for blocking light emitted from the light emitter from entering the ambient environment. In an exemplary aspect of the invention, the light emitter is a laser, such as a vertical cavity surface emitting laser (VCSEL). Moreover, in an exemplary aspect of the invention, the optical transmitter includes a housing, which has a recess for receiving a fiber optic connector. However, the concepts of the present invention may be used with any light emitter and/or any optical transmitter, without departing from the spirit and scope of the present invention.  
           [0016]    To reduce the risk of light, such as laser light for example, from inadvertently entering the ambient environment, in an exemplary aspect of the invention, the light blocking device is adapted to at least partially cover an opening of the recess when the fiber optic connector is removed. Thus, the light emitted from the laser will impinge upon the light blocking device, and will be prevented from escaping into the ambient environment.  
           [0017]    In a further exemplary aspect of the invention, the light blocking device has an opaque flap that is disposed in the recess when the fiber optic connector is received within the recess, and which automatically moves to a position in which the flap at least partially covers the recess when the fiber optic connecter is removed. In this aspect of the invention, when the fiber optic connecter is inserted within the recess, the fiber optic connector pushes the flap to a side of the recess, and out of the way, to allow the fiber optic connector to be coupled to the housing. For example, the flap can be pushed toward a top of the recess. Alternatively, it is also contemplated that the flap could be pushed to the lateral sides or the bottom of the recess.  
           [0018]    In another exemplary aspect of the invention, the light blocking device further includes a thin panel member, to which the flap is joined. The panel member may be connected to the housing, for example the upper outer surface of the housing, and arranged so that the flap is disposed over the opening of the recess, when there is no fiber optic connector attached thereto. For example, in one aspect of the invention, the panel member may be adhered to the upper surface of the housing portion. With such an arrangement, the panel member may also serve as a label, and be provided with information data regarding the transceiver. Alternatively, or in combination to the adhesive, a conductive EMI shield may be disposed over the panel member to help hold the panel member against the surface of the housing portion.  
           [0019]    In a further exemplary aspect of the invention, the flap is integrally formed with the panel member. This allows the flap and panel member to be molded, for example, to have a predefined configuration. Moreover, the resulting device will have a memory effect that will help to retain the flap and panel member in this predefined configuration, when no other forces are present. By way of example, the flap may be arranged to be essentially perpendicular to the panel member. The term “essentially perpendicular” is understood to mean that the flap, for example, is arranged in a generally vertical direction, whereas the panel member is arranged in a generally horizontal position. Thus, when the panel member is attached to the surface of the housing, the flap will project over the opening of the recess. When the fiber optic connector is inserted into the recess, the fiber optic connector will push the flap toward a side of the recess, so that the flap and the panel member will be essentially parallel to each other. When the fiber optic connector is removed from the recess, the memory effect of the flap and panel member will cause the flap to automatically move back to its natural position, which in the exemplary embodiment is essentially perpendicular to the panel member.  
           [0020]    It is contemplated that other configurations of the flap and panel member are possible within the spirit and scope of the invention. For example, the flap may be separately hinged to the panel member. With this arrangement, gravity could be used to move the flap to a position in which the opening of the recess is covered. Of course, this would require a redefined arrangement of the optical transmitter. Alternatively, a spring could be provided to move the flap to the position in which the opening of the recess is covered. However, this aspect of the invention requires more parts, and would increase assembly time.  
           [0021]    It is also contemplated that the flap be directly joined, either integrally or using a separate hinge, to the housing, so that the panel member could be eliminated. However, it is currently believed that the use of the panel member facilitates assembly. Moreover, when a panel member is provided, the light blocking device can be easily adapted for use with conventional optical transceivers.  
           [0022]    In the above described exemplary embodiments, the flap and panel member are formed from a mylar/polymide material. This material can provide the desired light blocking capability, and provide the desired memory effect discussed above. However, the flap and/or the panel member may be formed of other materials without departing from the spirit and scope of the invention.  
           [0023]    Further, although in the above-described exemplary embodiments one flap projects down from the upper surface of the housing, it is contemplated that the flap can project from any of the surfaces of the housing. Moreover, it is further contemplated that more than one flap may be provided. For example, one flap could be provided at the top of the recess opening, and another flap could be provided at the bottom of the recess opening. This configuration may be advantageous when one flap alone does not adequately cover the recess opening.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 is a rear perspective view of an exemplary optical transceiver that could be used with the light blocking device of the present invention.  
         [0025]    [0025]FIG. 2 is a side sectional view of the optical transceiver shown in FIG. 1.  
         [0026]    [0026]FIG. 3 is a perspective view of the optical transceiver shown in FIG. 1, being disposed within a computer, and having a heat sink, wiring board, and the EMI shield shown in FIG. 3 attached thereto, and being used with the light blocking device according to an exemplary aspect of the invention.  
         [0027]    [0027]FIG. 4 is a perspective view of an EMI shield that may be used with the optical transceiver shown in FIG. 1.  
         [0028]    [0028]FIG. 5 is a partial front view of the arrangement shown in FIG. 3.  
         [0029]    [0029]FIG. 6 is a partial side sectional view of the arrangement shown in FIG. 3.  
         [0030]    [0030]FIG. 7 is an enlarged partial sectional view, taken from section VII shown in FIG. 6.  
         [0031]    [0031]FIG. 8 is a perspective view of the light blocking device according to an exemplary aspect of the invention.  
         [0032]    [0032]FIG. 9 is a perspective view of an alternative exemplary optical transceiver, being used with the light blocking device according to an exemplary aspect of the invention, and having a heat sink and wiring board connected thereto. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    The invention will now be described in more detail by way of example with reference to the embodiments shown in the accompanying figures. It should be kept in mind that the following described embodiments are only presented by way of example and should not be construed as limiting the inventive concept to any particular physical configuration.  
         [0034]    Further, in the application, the terms “upper”, “lower”, “front”, “back”, “over”, “under”, “horizontal”, “vertical”, and similar such terms are not to be construed as limiting the invention to a particular orientation. Instead, these terms are used only on a relative basis.  
         [0035]    The present invention is directed toward a device that can be used with a light emitter, such as those used within optical transmitters, for blocking light emitted from the light emitter from entering the ambient environment. In an exemplary aspect of the invention, the light emitter is a laser, such as a vertical cavity surface emitting laser (VCSEL). Further, the optical transmitter can be of the type disclosed in corresponding U.S. patent application Ser. No. ______, attorney docket no. ROC920010219US1-IBM-213, entitled Integrated Optical Coupler and Housing Arrangement, and Ser. No. 09/894,934, attorney docket no. ROC920010154US1-IBM-212, entitled Enhanced Optical Transceiver Arrangement, both having been assigned to International Business Machines, Corporation. However, the concepts of the present invention may be used with any optical transmitter, and/or any light emitter, without departing from the spirit and scope of the present invention.  
         [0036]    Briefly, and referring to FIGS. 1 and 2, this exemplary optical transmitter includes a housing  10  that has a recess  12  for selectively receiving either an industry standard MPO or MTP fiber optic connector (not shown), for example. As is conventional, the fiber optic connector will be disposed at an end of a fiber optic cable.  
         [0037]    A back surface of the recess  12  is defined by an end surface of an optical coupler  14 . The optical coupler  14  may be an integral feature of the housing  10  as shown, or may be a separate component that is attached to the housing  10 . Further, the optical coupler  14  has a plurality of spaced apart optical fibers  16 , each of which extends from one end surface of the optical coupler  14  to the other end surface. When the fiber optic connector is received within the recess  12 , the optical fibers  16  of the optical coupler  14  will be positioned adjacent to the fiber optic connector. The optical fibers  16  of the optical coupler  14  are used to transmit optical signals between the optical fibers of the fiber optic cable and active regions of a light emitter  18 , such as a VCSEL (see FIG. 7).  
         [0038]    Referring also to FIG. 3, the housing  10  may be provided with a pair of latching fingers  20  disposed on opposite sides of the recess  12 . The latching fingers  20  are adapted to engage with the fiber optic connector, to hold the connector within the recess  12 .  
         [0039]    If desired, first and second housings  10  may be disposed side-by-side, each of which contains an optical coupler  14 . This configuration allows both a light emitter and a light detector, for example, to be disposed in the same assembly, therefore saving circuit board space. The respective housings can be manufactured separately and joined together, for example, or the two housings can be integrally molded together.  
         [0040]    Referring also to FIGS. 4 and 5, the front end of the housing  10  may also be provided with an electromagnetic interference shield  22 . The electromagnetic interference shield  22  is preferably formed from a conductive, non-corrosive material, such as steel having a tin plating. However, the electromagnetic interference shield  22  can be formed of any material that will attenuate electromagnetic interference.  
         [0041]    As shown, the electromagnetic interference shield  22  is hollow, to allow the shield to be slipped over the front end of the housing  10 . When properly positioned, the edge of the electromagnetic interference shield  22  will be positioned essentially flush with the front end of the housing  10 . The shield  22  may be provided with inwardly projecting fingers  24  that engage with the surface of the housing  10 , to hold the shield in place.  
         [0042]    The electromagnetic interference shield  22  may be provided with a number of conductive grounding springs  26 , which are disposed around the outer periphery of an end of the shield. The grounding springs  26  engage, for example, with a tailstock  28  attached to a system frame  30  of a computer, for example, to conductively couple the electromagnetic interference shield  22  to a ground potential. When properly positioned, the grounding springs  26  hold the electromagnetic interference shield  22  in a fixed position relative to the tailstock  28 .  
         [0043]    By way of example, the grounding springs  26  can be formed as metal fingers which initially extend in the same plane, and contiguous with, a respective wall of the shield  22 . The metal fingers can then be bent so that the fingers are disposed at an angle relative to the respective walls they are attached to. Due to the memory effect of the material, the fingers will then exert a spring force that acts in a direction away from the walls. Thus, the metal fingers can engage with the tailstock, in the aforementioned manner.  
         [0044]    The shield  22  can be used to hold the first and second housings together, when two separate housings are provided. That is, the shield  22  can be slid around the adjacent housings  10 , and serve as a clamp to retain the housings in their relative positions.  
         [0045]    Referring also to FIGS. 6 and 7, the exemplary optical transmitter further includes a die carrier  32 , having opposing lands  34  (only one being shown in the side view of FIGS. 6 and 7). The opposing lands  34  have a receiving space therebetween, in which the light emitter  18  is disposed.  
         [0046]    The carrier  32  may be manufactured from a conductive material, so that it can serve as a ground for the light emitter  18 . For example, the carrier  32  can be formed from copper, and be gold plated to enhance its conductivity and reduce its susceptibility to oxidation. However, it is contemplated that the carrier  32  can be manufactured from other materials without departing from the spirit and scope of the invention.  
         [0047]    The lands  34  are adapted to allow the optical coupler  14  to be attached thereto. For example, each land  34  can be provided with a receiving and alignment hole (not shown). Further, the end surface of the optical coupler  14  may have an alignment pin  36  or pins that projects therefrom (see FIG. 1). In the illustrated exemplary embodiment, the alignment pins  36  are disposed to flank the optical fibers  16 . The alignment pins  36  are received within corresponding receiving and alignment holes in the lands  34 , to align and fix the optical coupler  14  to the die carrier  32 . Similarly, the other end surface of the optical coupler  14  may be provided with alignment pins  36  (see FIG. 5) which are insertable within corresponding holes formed in the fiber optic connector, to align and fix the optical coupler to the fiber optic connector.  
         [0048]    The lands  34  may be adapted to project out slightly beyond the light emitter  18 . This configuration prevents the optical coupler  14  from having direct contact with the active regions (i.e., the regions that emit the light) of the light emitter  18 .  
         [0049]    The housing  10  and die carrier  32  may be disposed on a wiring board  38 , which may have electronic circuitry and devices  40  for controlling the light emitter  18 . This wiring board  38  may then be electrically coupled to a mother board  39 , for example, of the computer shown in FIG. 3. Moreover, a heat sink  42  may be provided over the housing  10 , die carrier  32  and wiring board  38  to help dissipate any generated heat.  
         [0050]    With the above described optical transmitter, if the fiber optic connector is removed from the recess  12  while the optical transmitter is operating, light emitted from the active regions of the light emitter  18  may enter the ambient environment. As previously discussed, if the light emitter  18  is a laser, this could be particularly disadvantageous. Referring also to FIGS. 8 and 9, to reduce the risk of this occurring, in an exemplary aspect of the invention, a light blocking device  44  is provided that at least partially covers the opening into the recess  12  when the fiber optic connector is removed. Thus, the light emitted from the laser will impinge upon the light blocking device  44 , and will be prevented from escaping into the ambient environment.  
         [0051]    In one exemplary aspect of the invention, the light blocking device  44  has an opaque flap  46  that is disposed in the recess when the fiber optic connector is received within the recess, and which automatically moves to a position in which the flap at least partially covers the recess when the fiber optic connecter is removed. In this aspect of the invention, when the fiber optic connecter is inserted within the recess  12 , the fiber optic connector pushes the flap  46  to the side of the recess, and out of the way, to allow the fiber optic connector to be coupled to the housing  10  in the aforedescribed manner. For example, the flap  46  can be pushed toward a top of the recess  12  as shown. Alternatively, it is also contemplated that the flap  46  could be pushed to the lateral sides or the bottom of the recess  12 .  
         [0052]    In the illustrated exemplary embodiment, the light blocking device  44  further includes a thin panel member  48 , to which the flap  46  is joined. The panel member  48  may be connected to the housing  10 , for example the upper outer surface of the housing, and arranged so that the flap  46  is disposed over the opening of the recess  12 , when there is no fiber optic connector attached thereto. For example, in one aspect of the invention, the panel member  48  may be adhered to the upper surface of the housing  10 . With such an arrangement, the panel member  48  may also serve as a label, and be provided with information data regarding the transceiver. Alternatively, or in combination to the adhesive, the conductive shield  22  may be disposed over the panel member  48  to help hold the panel member against the surface of the housing  10 .  
         [0053]    In a further exemplary aspect of the invention, the flap  46  is integrally formed with the panel member  48 . This allows the flap  46  and panel member  48  to be molded, for example, to have a predefined configuration. Moreover, the resulting device will have a memory effect that will help to retain the flap  46  and panel member  48  in this predefined configuration, when no other forces are present. By way of example, this predefined configuration may have the flap  46  arranged to be essentially perpendicular to the panel member  48 . The term “essentially perpendicular” is understood to mean that the flap  46 , for example, is arranged in a generally vertical direction, whereas the panel member  48  is arranged in a generally horizontal position. Thus, when the panel member  48  is attached to the surface of the housing  10 , the flap  46  will project over the opening of the recess  12 . When the fiber optic connector is inserted into the recess  12 , the fiber optic connector will push the flap  46  out of the way and toward a side of the recess, so that the flap and the panel member  48  will be essentially parallel to each other. When the fiber optic connector is removed from the recess, the memory effect of the flap  46  and panel member  48  will cause the flap to automatically move back to its natural position (i.e., the predefined configuration), which in the exemplary embodiment is essentially perpendicular to the panel member.  
         [0054]    It is contemplated that other configurations of the flap  46  and panel member  48  are possible within the spirit and scope of the invention. For example, the flap  46  may be separately hinged to the panel member  48 . With this arrangement, gravity could be used to move the flap  46  to a position in which the opening of the recess  12  is covered. Of course, this would require a redefined arrangement of the optical transmitter, in order to ensure gravity will move the flap to the desired position. Alternatively, a spring could be provided to move the flap  46  to the position in which the opening of the recess  12  is covered. However, this aspect of the invention requires more parts, and would increase assembly time.  
         [0055]    It is also contemplated that the flap  46  be directly joined, either integrally or using a separate hinge, to the housing  10 , so that the panel member  48  could be eliminated. However, it is currently believed that the use of the panel member  48  facilitates assembly. Moreover, when a panel member is provided, the light blocking device can be easily adapted for use with conventional optical transceivers.  
         [0056]    In the above described exemplary embodiments, the flap  46  and panel member  48  are formed from a mylar/polymide material. This material can provide the desired light blocking capability, and provide the desired memory effect discussed above. However, the flap and/or the panel member may be formed from other materials without departing from the spirit and scope of the invention.  
         [0057]    Further, although in the above-described exemplary embodiments one flap projects down from the upper surface of the housing, it is contemplated that the flap can project from any of the surfaces of the housing. Moreover, it is further contemplated that more than one flap may be provided. For example, one flap could be provided at the top of the recess opening, and another flap could be provided at the bottom of the recess opening. This configuration may be advantageous when one flap alone does not adequately cover the recess opening.  
         [0058]    It should be understood, however, that the invention is not necessarily limited to the specific arrangement and components shown and described above, but may be susceptible to numerous variations within the scope of the invention.  
         [0059]    It will be apparent to one skilled in the art that the manner of making and using the claimed invention has been adequately disclosed in the above-written description of the preferred embodiments taken together with the drawings.  
         [0060]    It will be understood that the above description of the preferred embodiments of the present invention are susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.