Abstract:
An underwater camera housing provided with an adaptive mechanical control arrangement for use with a broad range of camera brands and models. The camera housing is preferably formed of front and rear housing sections that are molded of clear transparent plastic and arranged to be moved between an open position for mounting a camera within the housing and a closed position in which the housing provides a watertight enclosure for protecting and communicating with a camera. The housing is provided with a truncated hemispherical lens through which a camera views scenes to be photographed to reduce distortion and not foreshorten viewing angle and a flat window and optional diffuser for providing controlled artificial illumination to a scene. A mounting plate is structured to slideably fit into one of the housing halves in one of two lateral orientations and includes a slidably adjustable camera mounting plate that permits a user to securely and accurately position cameras side-to-side and for and aft with respect to truncated hemispherical lens. Push button assemblies adjustable in length and point of contact are used to permit a user to adapt them to interact with a variety of camera control actuator architectures.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of priority from U.S. Provisional Patent Application No. 61/001,012 filed on Oct. 30, 2007 in the name of Stephen J. Fantone, et al. with the title UNDERWATER ADAPTIVE CAMERA HOUSING, the entire contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   This invention in general relates to housings for conventional cameras (film or digital, but primarily digital) and other digital devices with integral photographic capability to be used for underwater applications and, more particularly, to underwater camera housings that are adaptable for use with a wide range of cameras having different user interface architectures. 
   For a variety of reasons, camera manufacturers do not adhere to any standard layout for the arrangement, function, and operation of the controls that must be used in the course of taking pictures. Digital cameras with added displays and menu driven selections for control of camera functions and picture taking settings introduce additional complexity and diversity. As a consequence, makers of underwater camera housings have been forced to provide designs that match the control requirements of individual camera models. Thus, most underwater camera housings are more or less uniquely designed for specific camera models and will work with no others or, at best, with a narrow range of cameras. The fact that each camera requires a unique underwater housing obviously results in higher prices since there is no opportunity to take advantage of economies of scale. In addition, every time a user acquires a new camera, a corresponding new underwater housing must be purchased to match that camera&#39;s control arrangement. 
   In addition to the problems associated with the need for unique underwater camera housings for every camera, other problems exist with current underwater housings for all cameras. One of these has to do with the optical properties of underwater housings. Typically, a flat window is provided so that the camera taking lens can “see” what a diver intends to photograph. However, the use of flat windows introduces undesirable distortion and narrows the camera&#39;s inherent field of view. Moreover, housings with flat transmission windows often cause artificial light from a camera to reflect into the camera where it becomes an unwanted part of the photograph thus degrading its quality. 
   In view of the many problems associated with known underwater camera housings, it is a primary object of the present invention to provide a universal underwater camera housing that can be used with a large range of commercially available film and digital still and video cameras and other digital devices such as PDAs and cell phones equipped with photographic functionality. 
   It is another object of the present invention to provide underwater camera housings with improved optics for film and digital photography. 
   It is still another object of the present invention to provide underwater camera housings having interior features for controlling reflections from camera strobes and the like so that they do not reach a camera&#39;s detector or film as stray light. 
   Other objects of the invention will in part be obvious and will in part appear hereinafter when the following detailed description is read in connection with the appended drawings. 
   SUMMARY OF THE INVENTION 
   The present invention relates to an underwater adaptive camera housing for providing a watertight enclosure and common control interface for cameras and the like. The housing preferably includes two or more housing sections that are moveable between an open and a closed position in which a camera of the type described is mounted within an enclosure sealed from exposure to surrounding water. At least one of the sections has a transparent, preferably truncated hemispherical-shaped, picture taking window that permits light to be received by an enclosed camera. A locking arrangement keeps the housing sections from freely opening when in the closed position. An adjustable inner mount secures cameras in the housing at a position in optical alignment with the transparent picture taking window. A second flat window is provided in the housing above the picture taking window for emitting strobe illumination to a scene. An optional diffuser may be mounted outside of the housing forward of the illumination window to control the pattern of illumination over the scene. Push button assemblies adjustable in length and point of contact are provided to permit the camera housing to be used with a wide variety of commercially available cameras. 
   In one aspect of the invention, the transparent picture taking window&#39;s preferably truncated hemispherical shape operates to prevent back reflection from internal illumination sources, reduces distortion, increases field of view, and accommodates a variety of different sized and shaped cameras. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure, operation, and methodology of the invention, together with other objects and advantages thereof, may best be understood by reading the detailed description in connection with the drawings in which each part has an assigned numeral that identifies it wherever it appears in the various drawings and wherein: 
       FIG. 1A  is a diagrammatic view of an underwater camera housing in accordance with the invention along with an enclosed camera, looking down at them from an upper front right corner perspective; 
       FIG. 1B  is a diagrammatic top view of the camera housing of  FIG. 1 ; 
       FIG. 2  is an exploded diagrammatic perspective view of the housing camera and of  FIG. 1 ; 
       FIG. 3  is a diagrammatic view of the underwater housing and camera of  FIG. 1  looking at them from an upper rear left corner perspective; 
       FIG. 4  is simplified diagrammatic top view of the camera and underwater housing of  FIG. 1  illustrating various optical features; 
       FIGS. 5A and 5B  are diagrams showing the differences in field of view between a flat camera window versus the truncated hemispherical lens window of the invention; 
       FIGS. 6A and 6B  are plots of differences in distortion for a flat camera window versus the truncated hemispherical lens window of the invention; 
       FIG. 7A  is an exploded diagrammatic perspective view of an adaptable camera actuator assembly adjustable in length and point of application within the camera housing of  FIG. 1 ; 
       FIG. 7B  is an exploded diagrammatic perspective view of the adaptable camera actuator assembly of  FIG. 7A  shown in conjunction with a separately supplied assembly tool; and 
       FIG. 7C  is an assembled diagrammatic perspective view of the adaptable camera actuator assembly of  FIG. 7A  shown in conjunction with the separately supplied assembly tool and an unattached length extension member. 
   

   DETAILED DESCRIPTION 
   The present invention relates to an underwater camera housing having an adjustable mechanical control interface to adapt it for use with a broad range of camera brands and models. The cameras may be conventional still and video film cameras, digital still and video cameras, or digital devices provided with photographic capability, such as cell phones or PDAs having integrated digital cameras. 
   Reference is now made to  FIGS. 1A ,  1 B,  2  and  3 , which show an adaptive underwater camera housing, generally designated at  10 , in accordance with the invention, along with a digital camera  15  located inside of housing  10 . These figures show, respectively, an upper right front perspective view, a diagrammatic top view, an exploded perspective view, and an upper-rear perspective view of the inventive underwater housing  10  including its control features where  FIG. 2  is an exploded perspective view of  FIG. 1 . As seen in those figures, underwater housing  10  comprises rear and front housing sections,  100  and  120 , respectively, that are adapted to mate in complementary fashion to form a watertight enclosure for accommodating one of many still or video cameras available in the marketplace, including those of the major brands. Housing sections  100  and  120  are preferably injection molded of an optically clear engineering plastic such as acrylic (index of refraction of 1.492) or polycarbonate (n=1.585). 
   Camera  15  is secured within housing  10  by a mounting mechanism which allows the position of a camera to be adjusted so that its taking lens  17  is aligned in X, Y, and Z with respect to a truncated hemispherical shaped lens window  130 . As seen in  FIG. 2 , camera  15  is fixedly attached and screwed tight to a slotted mounting plate  60  via its tripod interface  69  (See  FIG. 2 ). As described more fully hereinafter, the mounting mechanism in one embodiment includes the mounting plate  60  and a sliding truck  67  (shown in  FIG. 2 ) which insert in rear camera housing  100  for placement of camera  15  along the Z-direction (optical axis), and perpendicular to it (X, and Y directions). 
   As explained further with reference to  FIG. 4 , truncated hemispherical shaped lens taking window  130  reduces distortion and controls the disposition of back reflections that would otherwise occur when light from internal light sources reflect off interior housing features. If not controlled by the use of the generally hemispherical window, such reflections could otherwise reflect into taking lens  17  where they could ultimately strike a camera&#39;s film or detector as unwanted stray radiation that would reduce the quality of the image 
   As shown in  FIGS. 1A and 2 , front housing section  120  has a vertically extending flat window  135  sitting just above the shelf that truncates otherwise hemispherical taking window  130 . The flat window  135  aligns with a camera&#39;s strobe to provide artificial light for illuminating a scene to be imaged. However, because the strobe window  135  is flat, it reduces the angular field of illumination of strobes so an optional diffuser  131  may be provided to control the illumination pattern and mitigate against any shadowing caused by the housing itself and any internal baffles. In this connection also, an internal baffle (not shown) may be provided underneath the shelf of the truncated hemispherical taking lens window  130  to prevent light from a strobe or the like from entering the truncated hemispherical taking lens window and thus entering a camera&#39;s taking lens as unwanted radiation. The optional internal baffle may be made of opaque flocking or mylar material and held in place with nubs or adhesive. Optional diffuser  131 , when used, is designed so that it controls the pattern of illumination provided to match the taking field of the camera and is adjusted for parallax effects. To achieve this, optional diffuser  131  is preferably provided with a series of 90-degree elongated grooves that are normally horizontally oriented to control illumination up and down. Diffuser  131  mounts to the exterior surface of front housing section  120  via a pair of cylindrically shaped, forwardly extending bosses  132 . 
   Because it is transparent, the rear wall of rear housing section  100  acts as a window so that visual displays (e.g., menus, picture previews, etc.) of information located at the rear of camera  15  may be seen when a camera is inside housing  10 . Rear housing section  100  also has a bumped out section  125  that serves as a handle for gripping and manipulating housing  10  while being used underwater or otherwise being handled or transported. A lanyard may also be attached to housing  10  for transporting it underwater without physically gripping it by hand. 
   Referring again to  FIG. 2 , it can be seen that rear and front housing sections,  100  and  120 , respectively, are mated with an intervening watertight O-ring  67  and are held together in the closed mated position by left and right side locking mechanisms, each designated generally at  55 . Locking mechanisms  55  are pivotally attached to back housing section  100 , and each have levers  50  for locking the housing sections in their mated closed position and for releasing them for opening. Levers  50  rotate about corresponding shafts  72  drawn through upper and lower cantilevered tabs  75  and  77  (shown in  FIG. 2 ). Pivotally connected to levers  50  via longer shafts  57  are latch sections  70  that are configured to grip a rim  101  partially surrounding front housing section  120 . The various parts forming the latch mechanism are configured and arranged to provide an over-the-center arrangement to clamp shut and release front housing section  120  against rear housing section  100  while compressing intervening O-ring  67  to provide a seal between them. 
   In a variant of the clamping arrangement above, the sections of housing  10  can be semi-permanently sealed with the use of RTV or the like. 
   As seen in  FIG. 3 , the controls of camera  15  are actuatable from the outside of camera housing  10  via a mechanical push button interface comprising an array of adaptable push button assemblies, designated generally at  40 , located on bumped out section  125  of rear housing section  100  and a single push button assembly, also  40 , sitting atop camera front housing section  120 . Adaptable push button assemblies  40  are, in a manner to be described, adjustable in length and point of contact to permit a user to adapt them to interact with a variety of camera control actuators. The features of push button assemblies  40  that provide their manner of adaptability while preserving the water tightness of camera housing  10  will be described in more detail hereinafter in connection with  FIGS. 7A , B, and C. 
   Reference is now made to  FIG. 4  once again where the optical features of front housing section  120  are shown. As mentioned earlier, the transparent taking window  130  through which the camera taking lens views a scene is made hemispherical to reduce distortion and maintain a camera&#39;s angular field compared with what it would otherwise be using a flat taking window. This can be appreciated by referring now to  FIGS. 5A and 5B  which show, respectively, the path of a ray of light as it transits a flat window in an air-water interface as opposed to the path of the same ray transiting the truncated hemispherical taking window of the present embodiment. As can be seen, rays transiting the interface through the hemispherical window do not change direction and hence field of view is unaltered, whereas with a flat window, it is reduced.  FIGS. 6A and 6B  show, correspondingly, a map of distortion on an image from a flat shaped window ( FIG. 6A ) and that from a hemispherical taking window. Clearly,  FIG. 6B  demonstrates that the use of the hemispherical window of the invention substantially eliminates distortion while beneficially not foreshortening the angular field of view of a camera&#39;s taking lens. The radius of curvature of hemispherically shaped taking window  130  is preferably otherwise designed to accommodate the full focusing range of a large group of cameras operating in their tele, wide angle, and macro modes over their full zoom range. The range over which the radius can sensibly vary is from approximately 1.0 inches to 6.0 inches. The wall thickness of the camera housing is approximately 0.125 inches. 
   Referring back to  FIG. 4 , the camera taking lens  17  and optical axis  140  of the hemispherical window are nominally coincident with the entrance pupil of the taking lens  17 . The taking lens entrance pupil preferably nominally resides in a plane  145  perpendicular to those optical axes and passing through the entrance pupil center. The hemispherical window  130  is preferably of uniform thickness. One exemplary design having a focal length of −8.4 inches is made of polycarbonate with a radius of three inches and a thickness of 0.125 inches. Given this design, the requirements for bore sighting a camera with respect to the optical axis of the hemispherical window and the placement of its lens entrance pupil along the optical axis are relatively relaxed; it being estimated that the placement of the entrance pupil along the optical axis can be off by +/− an inch before distortion similar to that produced by a flat window would begin to appear. 
   In addition to the benefits of low distortion, wide angular field of view, and relative insensitivity to camera placement, the hemispherical lens also permits reflections off it from off-axis illumination from the camera, such as built-in strobes, to be beneficially directed to the interior of the camera housing where it is not seen by the camera taking lens. This is possible because such strobes nominally reside in the vicinity of a plane located near the center of curvature of the hemispherical window, and thus light from them is directed to locations where it does not enter the taking lens as unwanted stray radiation that can affect image quality. 
   Reference is now made again to  FIG. 2 , which shows the mechanical arrangement previously mentioned for mounting and holding a camera in alignment with the hemispherical shaped window  130  formed in the front camera housing  120 . Here, camera mounting plate  60  is seen to be provided with a pair of spaced apart parallel slots  64  and a pair of spaced apart wedged ends  63  (only one shown). The spaced apart wedged ends  63  slide within a corresponding pair of complementary shaped, spaced apart grooved rails  65  located in rear housing section  100 . A truck  67  slides within spaced apart parallel slots  64 . A camera is secured to the truck  67  via a standard ¼-20 bolt  69  that screws to an underlying plate  61  that is adjustable fore and aft. As can also be seen, the plate aperture is bilaterally symmetric so that the plate  60  can be flipped right to left to place its aperture either to the right of left of rear camera housing  100 . This latter feature, in combination with the sliding truck  67 , permits the proper side to side and fore and aft location of the camera taking lens to be achieved thus permitting a camera  15  to be positioned side-to-side and fore and aft with respect to the hemispherical window  130 . Once fixed to the plate  60 , the camera can be slid into rear housing section  100  by placing the wedged ends  63  in the grooved rails  65  and sliding plate  60  along with an attached camera until seated in rear housing section  100 . Vertical alignment can be adjusted, as needed, by the use of spacers or shims that sit atop sliding truck  67 . Once in position, front housing section  120 , when mated with rear housing section  100 , traps plate  60  between the two to secure a camera in housing  10 . Those skilled in the art will appreciate that the market can be surveyed to determine optimal dimensions so that the underwater housing  10  can accommodate a large segment of available cameras. 
   Reference is now made to  FIGS. 7A ,  7 B, and  7 C, which show unassembled and assembled diagrammatic exploded views of the adjustable push button assembly  40  by which a variety of cameras having different actuator architectures can be operated underwater. To achieve this, each push button assembly is partially assembled to provide a water tight linear motion by actuation from the outside of the camera housing and afterwards finally adjucted by a user so that the linear motion is directed to a particular camera control. This is achieved through the use of a sliding arm adjustable in radial position and angle with respect to a fixed shaft along which the linear motion is first made. An extension at the end of the adjustable slider actually make final contact with a camera control and the length of extension may also be changed as needed. As will be appreciated, such actuators are for functions including turning camera power on and off, picture taking, zooming, previewing, and others. 
   As seen in  FIG. 7A , each adjustable push button assembly  40  comprises a push button  80  integrally molded with a shaft  82 , the end of which is threaded to receive a keeper  86  and a nut  88 . Located along the shaft  82  is a compression spring  92 , a retention washer  94  and an O-ring  96 . Compression spring  92 , washer  94  and O-ring  96  reside outside of camera housing  10 . O-rings  96  are placed in annular grooves provided in the bottom of raised pedestals  110  integrally molded into camera housing sections  100  and  120  (See  FIG. 1B ). Compression spring  92  and washer  94  are first placed over shaft  82  which is then pushed through a hole provided in the camera housing section (See  FIG. 1B ) after which the keeper is screwed to it to hold in place. In this connection, push button  80  has three spaced apart (120-degrees) vertically extending slots  104  that fit over correspondingly configured retention ribs  106  (See  FIG. 1B ) radially protruding into the interior of each pedestal  110  to prevent shaft  82  from rotating once pushed through a camera housing section. The dimensions of the various parts of the assembly are selected, however, so that, when a push button is depressed by a user, a predetermined throw distance is achieved. 
   Referring now back to  FIG. 7A , there can be seen a slotted arm  84  having a recessed groove  99  at the bottom of which is provided an elongated slot  102 . Keeper  86  fits inside of groove  99  while the remainder of threaded push rod  82  passes through elongated slot  102  where it is accessible to have nut  88  attached to it. Thus, the active length and angular position of arm  84  can be adjusted with respect to the axis of push shaft  82  by rotating it around shaft  82  after which it can be locked in place by tightening nut  88 . One or more camera button contact members  90  are pressed into the end of arm  84  to provide correct length in combination with the predetermined throw distance. In this connection, a separate adjusting tool  98  is provided to tighten nut  88 . Adjusting tool  98  may also be used to tighten the ¼-20 camera mounting bolt shown in  FIG. 2 . 
   The throw length of the assembly  40  along with the length of the camera button contact members  90  are selected to accommodate the largest range of camera actuator button locations. This adjustment feature, along with the adjustability in the angular and radial position of the slidable arm  84 , makes it possible to reach the largest number of camera control locations for a wide range of commercially available cameras. 
   Having described the invention with respect to specific embodiments, variations of it will be apparent to those skilled in the art based on its teachings. For example, camera contact button contact members  90  may be provided in different lengths. Consequently, such variations are intended to be within the scope covered by the appended claims.