Abstract:
An anti-condensation arrangement for an optical apparatus including a window mounted in a housing comprises an isolating member sealed around an end of an image collecting device of the optical apparatus and around a perimeter of the window, the isolating member substantially preventing airflow between a portion of the housing surrounding the isolating member and a space enclosed by the isolating member.

Description:
BACKGROUND  
       [0001]     Optical devices such as scanners and imagers are relied on for business and personal use in a wide variety of applications. Many of these devices are used in a variety of environments where rapid changes in temperature and humidity are common.  
         [0002]     As would be understood by those skilled in the art, a rapid change in the temperature of the air within the housing of such a device can cause condensation to build up on an optical window of the device, interfering with operation. Although, condensation on an outer surface of the window can be wiped away, condensation within the housing is a more difficult problem to address.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention is directed to an anti-condensation arrangement for an optical apparatus including a window mounted in a housing, the anti-condensation arrangement comprising an isolating member sealed around an end of an image collecting device of the optical apparatus and around a perimeter of the window, the isolating member substantially preventing airflow between a portion of the housing surrounding the isolating member and a space enclosed by the isolating member.  
         [0004]     The present invention is further directed to an apparatus for controlling airflow within a housing including an image capturing device and a window through which light is transmitted between the image capturing device and an outside of the housing. The apparatus comprises a first sealing surface sealingly engaging a perimeter of the image capturing device, a second sealing surface sealingly engaging a perimeter of the window and a wall separating a space between the first and second sealing surfaces from a remainder of a space within the housing, the wall substantially preventing air flow between an outside thereof and the space enclosed thereby. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  shows a perspective view of a mobile device including an anti-condensation arrangement according to a first embodiment of the present invention;  
         [0006]      FIG. 2  shows a perspective view of the device of  FIG. 1  with a top of a housing thereof removed to show the anti-condensation arrangement according to the first embodiment of the invention;  
         [0007]      FIG. 3  shows a perspective view of a front of an anti-condensation baffle of the anti-condensation arrangement of  FIG. 2 ;  
         [0008]      FIG. 4  shows a perspective view of a back of the anti-condensation baffle of  FIG. 3 ;  
         [0009]      FIG. 5  shows a perspective view of a mobile device including an anti-condensation arrangement with a top of a housing thereof removed to show the anti-condensation arrangement according to a second embodiment of the invention;  
         [0010]      FIG. 6  shows a perspective view of a front of an anti-condensation baffle of the anti-condensation arrangement of  FIG. 5 ; and  
         [0011]      FIG. 7  shows a perspective view of a back of the anti-condensation baffle of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION  
       [0012]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention will be described in regard to an anti-condensation arrangement for a laser scanning device and a digital imaging device. However, those skilled in the art will understand that these devices are exemplary only and that the anti-condensation arrangement according to the present invention may be applied to any device with a window.  
         [0013]     As shown in  FIGS. 1-4 , an optical device  10  which in this embodiment is a bar code scanner, includes a window  12  mounted in a housing  14  which includes, for example, a pistol grip  16  and a scanning actuator  18 . As shown in  FIG. 2 , a known scanning engine  20  is mounted within the housing  14  along with supporting electronics, a battery, etc. As would be understood by those skilled in the art, the position of the scanning engine  20  relative to the window  12  is determined based on properties of the scanning engine  20 , the window  12  and the desired functionality of the device  10 . Specifically, the device  10  is constructed in a manner similar to known optical devices (with the exception of the anti-condensation arrangement described below) with optical properties of the window  12  and the scanning engine  20  dictating an optimal distance between a forward end  22  of the scanning engine  20  and an inner face of the window  12  and, consequently, determining the size of a space  24  within the housing forward of the forward end  22  of the scanning engine  20 .  
         [0014]     An anti-condensation arrangement of the optical device  10  according to the present invention includes a baffle  26  which extends around the forward end  22  of the scanning engine  20  and encloses a portion of the space  24  including a line of sight for a laser or other light source of the scanning engine  20  and for light returning to the scanning engine  20  after reflection from a target. The baffle  26  seals around the forward end  22  of the scanning engine  20  to isolate the enclosed portion of the space  24  from the balance of the space  24  and from the interior space within the housing  14 . This reduces air flow between the enclosed portion of the space  24  and all other areas within the housing  14  except for such air flow as passes through the scanning engine  20  to the enclosed portion of the space  24 .  
         [0015]     Specifically, as shown in  FIG. 4 , a rearward facing portion of the baffle  26  includes a recess  28  which receives the forward end  22  of the scanning engine  20  with a sealing lip  30  sealingly engaging a perimeter of the forward end  22  of the scanning engine  20 . A forward end of the baffle  26 , as shown in  FIGS. 3 and 4 , includes a window receiving recess  32  with an optical opening  34  formed therein. A sealing lip  36  extends around a perimeter of the opening  34  to sealingly engage an inner perimeter of the window  12 , pressing an outer perimeter of the window  12  against the perimeter of an optical opening in the housing  14 .  
         [0016]     A wall  38  of the baffle  26  is preferably substantially continuous so that air flow to and from the enclosed portion of the space  24  through the wall  38  is substantially prevented. Of course, those skilled in the art will understand that the term continuous, in regard to this surface, is meant only with regard to the ability of air to pass therethrough and is not intended to limit the shape of the baffle  26  or any part thereof. Rather, the baffle  26  may be formed in any shape dictated by the shape and size of the housing  14  and the components to be included therein. In a preferred embodiment, the sealing lip  30  is joined to the forward end  22  of the scanning engine  20  to form an air-tight seal therewith while the sealing lip  36  forms an air-tight seal with the inner perimeter of the window  12 . As described above, this limits air flow between the enclosed portion of the space  24  and the rest of the interior of the housing  14  to air-flow passing to and from the enclosed portion of space  24  through the forward end  22  of the scanning engine  20 . However, those skilled in the art will understand that the baffle  26  need not completely seal the enclosed portion of the space  24 . Rather, to reduce condensation, the baffle need only restrict air flow to and from this enclosed portion of the space  24  to attenuate temperature fluctuations within the enclosed portion of the space  24 .  
         [0017]     The baffle  26  is preferably formed of a compressible material which will, for example, absorb the force of any impact to the front of the device  10  and attenuate this force before it reaches the scanning engine  20 . In a preferred embodiment of the invention, the baffle  26  is formed of GLS Versollan OM 1262NX available from GLS Corporation. As would be understood by those skilled in the art, the baffle  26  may be formed of any suitable rubber or foam material which exhibits the desired shock absorbing properties and which provides a desired level of impenetrability to air.  
         [0018]     As would be understood by those skilled in the art, the baffle  26  includes mounting features  40  which engage corresponding shapes of the engine mounting features to maintain the baffle  26  and the scanning engine  20  in desired positions relative to one another and to the housing  14 . Alternatively, the baffle  26  may be maintained in the desired position by a friction fit within the housing  14  and/or through engagement with the forward end  22  of the scanning engine  20 .  
         [0019]     As described above, rapid changes in the temperature of the air within the housing of an optical device can cause condensation to build up on a window of the device. However, with the device  10 , the air in the enclosed portion of the space  24  between the forward end  22  of the scanning engine  20  and the window  12  is substantially isolated from the air in the rest of the interior of the housing  14 . Thus, the temperature of the air in the enclosed portion of the space  24  varies more slowly than that in the rest of the housing  14  and, as air is interchanged with this enclosed portion of the space  24  only by passing through the scanning engine  20 , the temperature change of the air within the enclosed portion of the space is further attenuated by exposure to the warmth emanating from the scanning engine  20 . By slowing the rate of temperature change of the air within the enclosed portion of the space  24  and reducing the overall volume of air in contact with the window  12  and, thereby reducing the volume of water in that air, the anti-condensation arrangement of the present invention reduces the build up of condensation on the inner surface of the window  12 , enhancing the operation of the device  10 .  
         [0020]     An optical device  50  according to a second embodiment of the invention is shown in  FIGS. 5-7 . The device  50  is, for example, an imager (e.g., a digital camera), with an imaging unit  52  mounted within a housing  54  in a manner similar to that described above for the scanning engine  20 . However, those skilled in the art will understand that the size of a space  56  between a forward end  58  of the imaging unit  52  and a window  60  of the device  50  may be smaller than the space  24  of the device  10  (i.e., the distance required between the window  60  and the forward end  58  is often less than that required for scanners). Those skilled in the art will understand that these distances may vary significantly depending on the components and desired characteristics of these devices.  
         [0021]     The device  50  includes an anti-condensation arrangement including a baffle  62  which encloses a portion of the space  56  between the forward end  58  of the imaging unit  52  and the window  60 . Similarly to the anti-condensation arrangement of the device  10  described above, the anti-condensation arrangement of the device  50  substantially prevents air flow between the enclosed portion of the space  56  and the rest of the housing  54  except for air which flows through the imaging unit  52 .  
         [0022]     As shown in  FIG. 7 , a rearward facing portion of the baffle  62  includes a recess  66  in which the forward end  58  of the imaging unit  52  is received with a sealing lip  64  sealingly engaging a perimeter of the forward end  58 . In addition, as shown in  FIG. 6 , a forward end of the baffle  62  includes a plurality of openings  63  to accommodate illumination LED&#39;s as would be understood by those skilled in the art. In addition, a window receiving recess  65  is formed in the baffle  62  with an optical opening  67  formed therein. A sealing lip  68  extends around a perimeter of the opening  67  to sealingly engage an inner perimeter of the window  60 , pressing an outer perimeter of the window  60  against the perimeter of a window receiving opening in the housing  54 .  
         [0023]     As with the baffle  26 , a wall  70  of the baffle  62  is preferably substantially continuous so that air flow to and from the enclosed portion of the space  56  is substantially prevented. As described above, the term continuous, in regard to this surface, is meant only with regard to the ability of air to pass therethrough and is not intended to limit the shape of the baffle  62  or any part thereof. The baffle  62  may also be formed in any shape dictated by the shape and size of the housing  54  and the components to be included therein. In a preferred embodiment, the sealing lip  64  is joined to the forward end  58  of the imaging unit  52  to form a substantially air-tight seal therewith while the sealing lip  68  forms an air-tight seal with the inner perimeter of the window  60 . As described above, this limits air flow between the enclosed portion of the space  56  and the rest of the interior of the housing  54  to air-flow passing to and from the enclosed portion of space  56  through the forward end  58  of the imaging unit  52 . For example, the baffle  26  preferably restricts air flow into the enclosed portion of the space  24  by at least 80% as compared to a device without such a baffle while the baffle  62  restricts air flow to the enclosed portion of the space  56  by at least 90% as compared to a device without such a baffle. As would be understood by those skilled in the art, the difference in the restriction of air flow seen with the baffles  26  and  62  is substantially entirely due to difference in air flow through a scanning engine and a digital imager.  
         [0024]     Similarly to the baffle  26 , the baffle  62  is preferably formed of a compressible material such as, for example, GLS Versaflex, which will, for example, absorb the force of any impact to the front of the device  50  and attenuate this force before it reaches the imaging unit  52 .  
         [0025]     The baffle  62  includes mounting features  72  which engage corresponding shapes of the engine mounting features to maintain the baffle  62  and the imaging unit  52  in desired positions relative to one another and to the housing  54 .  
         [0026]     It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.