Abstract:
An adaptive underwater camera housing and control interface 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. Residing in the housing are a controller and communications interface by which a camera can be operated from outside the housing. Magnetic signals are preferably passed to the controller by external signal buttons operated by the user. The external signal buttons do not penetrate the interior surfaces of the housing thereby enhancing its water tightness. 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 diffuser for providing controlled artificial illumination to a scene.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of priority from earlier filed U.S. Provisional Patent Application No. 60/720,705 filed on Sep. 27, 2005 with the title UNDERWATER ADAPTIVE CAMERA HOUSING and U.S. Provisional Patent Application No. 60/830,224 filed on Jul. 12, 2006 with the title UNDERWATER ADAPTIVE CAMERA HOUSING, the contents of both of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     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 having exterior controls that do not extend through the wall of the housing forming the watertight enclosure in which the camera resides.  
         [0003]     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.  
         [0004]     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 arises because of the prevalent use of mechanisms that pass through camera housing walls to actuate camera controls by mechanical interaction as by manually pushing on a rod that has an end protruding from the exterior of the housing. Typically, such a push rod or the like is slidably mounted in a through hole in the housing and is surrounded by O-rings to prevent water from leaking into the housing. Such schemes rely on the integrity and cleanliness of the O-ring seals and their resistance to environmental effects. Often they will leak causing damage to the camera equipment they were expected to protect. In addition, the use of through holes in the housings creates local areas of high stress concentration, which increase with increasing water depth.  
         [0005]     Another problem 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.  
         [0006]     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.  
         [0007]     It is yet another object of the present invention to provide an underwater camera housing that can operate a camera with devices that reside solely outside of the housing, without the need for any housing through holes so that water tightness is enhanced and housing stress levels reduced.  
         [0008]     It is another object of the present invention to provide underwater camera housings with improved optics for film and digital photography.  
         [0009]     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.  
         [0010]     Another object of the present invention is to provide electronic control through the use of exterior signaling devices that can interact with interior controllers and communication interfaces to control camera functions and data transfer.  
         [0011]     It is yet another object of the present invention to provide a completely sealable underwater camera housing for a broad range of cameras and the like where camera power can be re-energized and data can be downloaded without breaking the seal.  
         [0012]     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  
       [0013]     The present invention relates to an underwater adaptive camera housing for providing a watertight enclosure and common control interface for cameras and the like that have remote electronic control capability. 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. A diffuser is mounted outside of the housing forward of the illumination window to control the pattern of illumination over the scene. A controller is mounted within the enclosure and is programmed to send and receive commands and data to an enclosed camera via a standard communications interface (such as USB), preferably using the Picture Transfer Protocol (PTP) standard. Externally mounted on the housing are human-operable signaling controls (e.g., buttons) that transmit signals to the controller, which subsequently transmits predetermined commands to the camera.  
         [0014]     In one aspect of the invention, no part of the human-operable signaling controls penetrate through the housing&#39;s inner surfaces and thus the housing&#39;s water tightness is enhanced when closed.  
         [0015]     In another 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.  
         [0016]     In another aspect of the invention, the controller is programmed with standardized command protocols (e.g., PTP, PIMA 15740:2000, Windows WIA) for communication with many commercial camera and video devices. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     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:  
         [0018]      FIG. 1A  is a diagrammatic view of an underwater camera housing and control system in accordance with the invention along with an enclosed camera looking down at them from an upper front right corner perspective;  
         [0019]      FIG. 1B  is a diagrammatic top view of the camera housing of  FIG. 1 ;  
         [0020]      FIG. 2  is an exploded diagrammatic perspective view of the housing camera and of  FIG. 1 ;  
         [0021]      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;  
         [0022]      FIG. 4  is top view of the camera and underwater housing of  FIG. 1  illustrating various optical features;  
         [0023]      FIGS. 5A and 5B  are diagrams showing the differences in field of view between a flat camera window versus the hemispherical lens window of the invention;  
         [0024]      FIGS. 6A and 6B  are plots of differences in distortion for a flat camera window versus the hemispherical lens window of the invention;  
         [0025]      FIG. 7  is a diagrammatic plan view of a reed switch and actuating magnet for use with the invention;  
         [0026]      FIG. 8  is a high level block diagram of the architecture of the adaptive camera housing of the invention showing the relationships and functions of its various components;  
         [0027]      FIG. 9  is a block diagram showing the hardware of the invention for implementing control functions and interfacing with a camera via a USB connector;  
         [0028]      FIG. 10  is a block diagram illustrating the layered protocol of the software of the invention; and  
         [0029]      FIG. 11  is a flowchart illustrating the various steps carried out by the software. 
     
    
     DETAILED DESCRIPTION  
       [0030]     The present invention relates to an adaptive underwater camera housing and control interface 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.  
         [0031]     Reference is now made to  FIGS. 1A, 1B ,  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 interface.  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).  
         [0032]     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 . 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  (shown in  FIG. 2 ) which slidably moves fore and aft with respect to rear camera housing  100  for placement of camera  15  along the Z-direction (optical axis), and perpendicular to it (X, and Y directions).  
         [0033]     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  
         [0034]     As shown in  FIGS. 2 and 3 , 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 a diffuser  131  has been 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  133  is 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 internal baffle  133  may be made of opaque flocking or mylar material and held in place with nubs or adhesive. Diffuser  131  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, 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 .  
         [0035]     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 . Front housing section  120  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.  
         [0036]     Now referring 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.  
         [0037]     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.  
         [0038]     As seen in  FIG. 3 , camera  15  has an electronic control interface (e.g., USB or other industry standard serial port) that is connected to a controller  20  inside housing  10  via a standard cable (not shown but see  FIG. 8, 206 ). In a manner to be explained in more detail later, camera  15  is selected such that it is remotely operable by one or more of many camera control protocols, such as PTP, PIMA 15740:2000, Microsoft WIA, or proprietary types defined by specific manufacturers. For instance, Nikon and Canon each implement their own version of the PTP protocol in their SDK for many of their cameras. Controller  20  may be programmed to function with one or more of these protocols. In one embodiment of the invention, an external selection switch (not shown) is actuated manually to signal to the controller  20  which of the various protocols is to be used to operate a specific brand and model of camera. In another embodiment of the invention, the controller  20  is configured to automatically detect, via USB, which type of control protocol is compatible with an enclosed camera. It will be apparent to those skilled in the art that the electronic controller  20  can be readily obtained in microcontroller form and that the interface, camera operation, and data transfer functions may be provided in one chip  
         [0039]     A vertical array of four identical external buttons  30  are provided on the rear housing section  100  and a single button  40  is provided on the top of rear housing section  100 . Buttons  30  reside On housing  31  and button  40  On housing  41 . Buttons  30  and button  41  carry magnets  89  (explained in more detail later) and are biased outwardly via springs  33  (See  FIG. 2 ). All are electronically connected to controller  20  and are used to remotely operate camera  15  through the camera&#39;s electronic interface. In an embodiment of the invention, the buttons  30  and  40  do not penetrate through the housing sections  100  and  120 , but instead transmit signals to the controller  20  through preferably magnetic actuation (e.g., reed, Hall-effect) thereby preventing potential leakage, which characterizes many through-hole type switches. If expense is not a consideration, waterproof switches of the spst momentary switching type may also be used. In addition, IR switches housed entirely inside of housing  10  may be used. With these, an IR light illuminates a wall section and reflects into an IR detector. A finger placed over the illuminated wall section changes the amount of reflection and hence serves as the basis for signaling. A wire (not shown) transmits signals from shutter control button  40  to controller  20  to snap a picture.  
         [0040]     Reference is now made to  FIG. 7 , which shows one form of reed switch that may be used. As seen there, a dry-reed switch  81  is provided as an assembly containing ferromagnetic contact blades  85  and  87 , hermetically sealed in a glass envelope  83  and operated by an externally-generated magnetic field, e.g., that from a permanent magnet  89  connected to spring loaded buttons  30  and  40 . The reed switches reside inside housing  10  and are actuated by moving a corresponding button ( 30 ,  40 ) provided with a permanent magnet. Individual magnets  89  may be rotated around their own axes to match magnetic fields to the requirements of corresponding individual reed switches with which they have been matched. They may then be fixed in place to a corresponding button as by gluing. In this manner, variations in the properties of reed switches can be compensated.  
         [0041]     Reference is now made to  FIG. 4 , which shows the optical features of front housing section  120 . As mentioned earlier, the transparent taking window  130  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 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.  
         [0042]     Referring back to  FIG. 4 , the camera taking lens  17  and optical axis 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.  
         [0043]     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.  
         [0044]     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 . This arrangement permits a camera  15  to be positioned side-to-side and fore and aft with respect to the hemispherical window  130 . This is done by simply selecting the proper slot ( 64 ) and sideways position of the camera along it, and then screwing the camera to plate  60  with a ¼-20 bolt  69  via the camera&#39;s standard tripod mount. Once this is done, camera  15 , now fixed to the plate  60 , 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 camera mounting plate  60 . 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.  
         [0045]     Reference is now made to  FIGS. 8 and 9 , which show the control and interface architecture and hardware by which a family of cameras can be operated underwater. The USB Camera Interface board, previously designated at  20 , acts as a USB host controller to emulate a PC and control the camera, which is now termed the USB Device. This can be done because current cameras can use the PTP transfer protocol as a communication protocol across a USB bus. The hardware for implementing this comprises a Philips LPC 2103 microcontroller (uC)  200  provided with a programming interface to implement control functions with the uC  200  running at 12 MHz (max 60 MHz). The hardware interface to the USB bus  206  is provided by a Cypress SL811HS interface chip  202 . Power to all components is provided by one or more AA alkaline batteries or a rechargeable (NiMH) battery, either of which resides in the camera housing  10 . Board  20  slides into the rear camera housing section  100  in a pair of spaced apart grooves and is trapped there by the front housing section  120 . The circuit requires 3 voltages. The USB host is required to supply 5V to the USB bus (device), The logic uses 3.3V, and the uC core uses a 1.8 V supply. A voltage booster  204  (TPS61010) and associated circuitry converts the battery&#39;s voltage (0.9 to 1.5 volts) to a regulated 3.3v and unregulated &gt;5v outputs. Linear regulators are used to derive regulated 5v and 1.8v from these supplies. The LPC2103 microcontroller  200  includes an A-to-D converter which can monitor the battery voltage and detect when the battery is reaching the end of its useful life. The user interface consists of switches  30  and switch  40  and LEDs ( FIG. 9 ) that are monitored and controlled by the uC  200 . The design above supports 5 switches and 4 LEDs, but currently calls for 4 switches and 3 LEDs. The USB controller  202  requires a 12 MHz clock for operation. In this design, the uC  200  is operated from a 12 MHz crystal, and the clock signal from the uC  200  is used to drive the controller  202 , as well. For faster operation, the microcontroller  200  can internally multiply the clock to a higher frequency (up to 5× or 60 MHz in this case), but the higher speed increases power consumption and is not needed in this application.  
         [0046]     The LPC2103 microcontroller  200  uses the ARM architecture, which is a commercially available architecture that is licensed and used by many manufacturers. A small assembly-language routine is used to initialize and configure the uC  200  on power-up. All other software is written in C using the GNU C compiler. The software is structured as a layered protocol as illustrated in  FIG. 10 . The lowest layer simply communicates with the SL811HS chip  202 , reading and writing its control and status registers). The next layer implements a minimal subset of the USB functionality that is required to initialize and control a camera. The PTP layer uses these USB functions to implement the PTP protocol that is used to send and receive commands and responses to the device. Finally, the main program monitors the switches and uses the PTP protocol to initiate the selected camera functions.  
         [0047]     A flowchart illustrating in more detail the various steps carried out by the software is shown in  FIG. 11 .  
         [0048]     Microcontroller  200  has 32 kB of on-chip flash program memory and 8 k of RAM, which is sufficient to support a number of cameras and implement the USB protocols and camera commands. It will be understood that, if necessary, memory can be increased as need be to accommodate additional cameras and/or functionality by selecting a more appropriate microcontroller.  
         [0049]     Also, flash memory can be reprogrammed after manufacture to support future enhancements or new camera models and protocols. There are 2 ways to do this:  
         [0050]     1) Use can be made of the serial port that is part of the microcontroller  200 . This is the normal way that a program is loaded into the microcontroller  200  during development or manufacturing. To do this, use is made of a small interface board to connect to the serial port of a PC and programming software. The parts cost of the interface is inexpensive, and programming software is available for free download from Philips.  
         [0051]     2) The chip  202  can function as either a host or device controller, so it can be connected to a PC&#39;s USB port to download program upgrades from the PC. The current board design includes parts to support this mode.  
         [0052]     A printed circuit board (not shown) may be used in a well-known manner for carrying all of the components shown in  FIG. 12 . Ultimately, such a printed circuit board becomes the board previously designated generally at  20 .  
         [0053]     In addition to providing signals to effect the camera functions illustrated, microcontroller  200  can be programmed to instruct a camera to provide other camera functions and to download image data as well.  
         [0054]     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, the housing sections can be permanently sealed with a camera inside in which case RF charging can be used to repower internal batteries or download data. In addition, IR links can be used for exchanging data and commands with a camera. Also, a modified version of a Digisnap 2000 controller may be used. This device is marketed by Harbortronics, Gig Harbor, Wash. One useful modified version of the Digisnap uses a Nikon serial port protocol adapted for use with, for example, Nikon Coolpix 8080, 8085, 9090, and 995 cameras. Moreover, the housing of the invention may readily be modified to accept larger cameras, such as SLRs and video types, by scaling and providing appropriate internal support structures, e.g., ribs, for enhanced rigidity and ability to withstand the larger forces generated with increased surface area. Consequently, such variations are intended to be within the scope covered by the appended claims.