Abstract:
A method for controlling behavior of a digital camera is disclosed. The method detects connectivity to a universal serial bus (USB) and automatically switches to a corresponding mode of operation depending on the result of the detecting.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    (1) Field of the Invention  
           [0002]    The present invention is in the field of digital cameras, more specifically, the method and apparatus of the present invention is related to controlling the behavior of a digital camera by detecting connectivity of the digital camera to a universal serial bus (USB) cable.  
           [0003]    (2) Related Art  
           [0004]    A digital camera like a traditional camera is capable of capturing images. Unlike a traditional camera, the digital camera focuses the images not onto light sensitive silver halide film but onto an image sensor made of a semiconductor material. One suitable image sensor of this type is known as a charge coupled device (CCD). The captured image data may then be converted to digital form by an analog-to-digital converter (ADC), compressed and stored in memory chips.  
           [0005]    Currently available digital cameras are either configured as a tethered digital camera or a portable digital camera. More specifically, tethered digital cameras are configured to be coupled to a computer system to capture images for processing by the computer system and do not function in a stand alone environment. Portable digital cameras are similar to the traditional cameras configured for hand-carry use. Unfortunately, it is expensive and space consuming for a user to have both a tethered digital camera as well as a portable digital camera.  
           [0006]    It is therefore desirable to have a method and apparatus that provides a dual-modality digital camera having the functionality of both a tethered digital camera as well as a portable digital camera and is capable of automatically switching between the two functionalities without user intervention.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    A method for controlling behavior of a digital camera is disclosed. The method detects connectivity to a universal serial bus (USB) and automatically switches to a corresponding mode of operation depending on the result of the detecting.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is an exemplary computer system block diagram with an implementation of the present invention.  
         [0009]    [0009]FIG. 2 is an exemplary illustration of the universal serial bus (USB) cable illustrated in FIG. 1.  
         [0010]    [0010]FIG. 3 a  illustrates a frontal view of an exemplary digital camera of the present invention.  
         [0011]    [0011]FIG. 3 b  illustrates an exemplary rear view of the digital camera of the present invention.  
         [0012]    [0012]FIG. 4 is an exemplary block diagram of the functional units of the present invention.  
         [0013]    [0013]FIG. 5 illustrates an exemplary block diagram of the dual mode control mechanism of the present invention.  
         [0014]    [0014]FIG. 6 illustrates an exemplary state machine of the present invention.  
         [0015]    [0015]FIG. 7 is a flow diagram illustrating the general steps followed by the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    The present invention supports dual mode operation in a digital camera for both portable and tethered mode functionality by automatically switching between the two functionalities without user intervention.  
         [0017]    [0017]FIG. 1 is an exemplary host computer system block diagram with an implementation of the present invention. Computer system  100  is coupled to a display device, such as a monitor  102  and to the present invention&#39;s digital camera  104 . The digital camera  104  is coupled to the host computer system  100  through a universal serial bus (USB) port  107  by a USB cable  106 . The USB cable  106  is coupled to the host computer system  100  via a USB serial port  108 . It may be appreciated by a person skilled in the art that although not shown, the host computer system  100  may be implemented with various other components typically found in a computer system.  
         [0018]    The digital camera  104  of the present invention is configured to support dual mode operation for both portable and tethered mode functionality by automatically switching between the two functionalities without user intervention. The tethered mode referred to herein is the mode in which the digital camera  104  is physically coupled to the host computer system  100  through, for example, a USB cable  106  via the USB serial port  108 . The portable mode referred to herein is the mode in which the digital camera  104  is functional when physically detached from the host computer system  100 .  
         [0019]    Although the host computer system  100  is illustrated in FIG. 1 as being coupled to only one digital camera, a person skilled in the art may appreciate from the detailed description provided herein that the present invention is capable of providing dual functionality to additional digital cameras couplable to the host computer system  100 .  
         [0020]    [0020]FIG. 2 is an exemplary USB cable  106  illustrated in FIG. 1. The USB cable  106  has a voltage bus (VBUS) line  200  and a ground (GND) bus line  202 . The VBUS line  200  is one of the four wires of a USB cable  106  and provides active current to the device attached to the USB cable  106 . The GND bus line  202  is a conductor having low impedance or high current carrying capacity, and feeds power to the digital camera  104 . The VBUS line  200  carries a positive VBUS signal  210 , and the GND bus line  202  carries a negative signal  212 . Further, the GND bus line  202  is coupled to ground  204 . The configuration of a typical USB cable with the four wires is well known in the art and needs no further discussion.  
         [0021]    In the present invention, the VBUS line  200  is coupled to a software readable register  207  which stores data indicative of whether the VBUS line  200  is carrying current (also referred herein as a VBUS signal  210 ). When the presence of a VBUS signal  210  on the USB serial port  107  is detected, the digital camera  104  operates in tethered mode. In tethered mode, all processing is initiated by commands which are sent through the host computer system  100 &#39;s USB serial port  108  to the digital camera  104 &#39;s USB serial port  107 . In one embodiment, the digital camera  104  has a limited command set which supports the digital camera activities, including capturing of still images and adjusting of parameters which control image exposure.  
         [0022]    If a VBUS signal  210  is not detected, the digital camera  104  operates in portable mode. In portable mode, the digital camera  104  responds to depressions of various buttons which are accessible on the external body of the digital camera  104  as is typical for a traditional hand carried digital camera. Any information captured is recorded in a non-volatile memory (not shown) within the digital camera  104 .  
         [0023]    The present invention&#39;s use of the VBUS signal  210  to control the digital camera  104 &#39;s behavior removes the need for having an extra user selectable switch to select between two modes. The convenience feature works in a fashion which is consistent with the user expectations of the required digital camera behavior, i.e., that tethered operations should automatically occur when the digital camera  104  is tethered.  
         [0024]    [0024]FIG. 3 a  illustrates a frontal view of an exemplary digital camera of the present invention. A digital camera  104  of the present invention has a USB serial port  107  to which the USB cable  106  is attached. The configuration of a USB serial port and a USB cable line and their attachments are well known in the art and need no further discussion.  
         [0025]    Digital camera  104  may also have a power switch  300  which when depressed activates the digital camera  104 , a sensor  302  which is configured to capture images, a strobe  304  (a flash bulb), and a shutter button  306  which initiates the capture of images when depressed.  
         [0026]    [0026]FIG. 3 b  illustrates an exemplary rear view of the digital camera of the present invention. The digital camera  104  of the present invention may also have a liquid crystal display (LCD)  308  which displays, for example, the number of images captured by the video camera  104 , and other status information. The digital camera  104  of the present invention may also have buttons  310  configured to activate various functions, including but not limited to changing the resolution of a captured image and enabling the strobe  304 .  
         [0027]    [0027]FIG. 4 is an exemplary block diagram of the functional units of the present invention. The digital camera  104  of the present invention has a microprocessor  400  which facilitates the execution of the firmware which controls the digital camera  104 .  
         [0028]    The digital camera  104  also has a storage element  402 . The storage element  402  may include, but is not limited to, a flash miniature card memory  406  for recording images captured by the digital camera  104  and a code flash memory  408  for storing software that controls the functionality of the digital camera  104 . The storage element  402  is coupled to the microprocessor  400  via a bus or buses  404 . The code flash memory  408  has a dual mode control mechanism  410  of the present invention which supports dual mode operation for portable and tethered mode functionality. A person skilled in the art may appreciate that although not shown, a digital camera  104  may have other components typically found in a digital camera.  
         [0029]    [0029]FIG. 5 illustrates an exemplary block diagram of the dual mode control mechanism  410  of the present invention. The dual mode control mechanism  410  of the present invention has a camera manager  501 . The camera manager  501  has a VBUS signal checker  500 , tethered mode manager  504  and a portable manager  506 .  
         [0030]    The present invention&#39;s camera manager  501  is implemented as a part of the firmware which controls the digital camera  104 &#39;s behavior and supports live automatic transition between the tethered and the portable behavior and vice versa. The VBUS signal checker  500  of the camera manager  501  periodically polls for USB connectivity to allow the camera manager  501  to dynamically adjust the digital camera  104 &#39;s behavior in real-time. The USB connectivity is detected by the presence of the VBUS signal  210  on the USB port  107 . The VBUS line  200  of the USB cable  106  carries a positive voltage supply, also referred herein as the VBUS signal  210 , to the digital camera  104  when connected.  
         [0031]    In one embodiment, the VBUS signal  210  on VBUS line  200  causes a VBUS bit  508  in a software readable register  207  to be asserted. More specifically, the software readable register  207  asserts a status bit referred herein as a VBUS bit  508  indicative of an asserted VBUS signal  210 . A VBUS checker  500  periodically polls the VBUS bit  508  and initiates the tethered mode when the VBUS bit  508  is asserted indicating that the VBUS signal  210  is on.  
         [0032]    The asserted VBUS bit  508  notifies the camera manager  501  that the digital camera  104  is connected to the host computer system  100  through the USB cable  106 . The camera manager  501  then enables a VBUS on message  502  indicating that the VBUS signal  210  is on and forwards the VBUS on message  502  to the tethered mode manager  504  and the portable mode manager  506 .  
         [0033]    If the VBUS signal  210  is on as indicated by the VBUS on message  502 , the tethered mode manager  504  is activated. The tethered mode manager  504  polls the USB serial port  107  for incoming commands issued by the host computer system  100  and the digital camera  104  performs functions in the tethered mode according to the commands. Otherwise, if the VBUS signal  210  is off, then the portable mode manager  506  is activated and processes functions on the digital camera  104  in the portable mode.  
         [0034]    More specifically, if a VBUS signal  210  is detected by the VBUS signal checker  500 , then the digital camera  104  is in tethered mode. All processing is initiated by commands which are sent by the host computer system  100  through the USB port  107  to the digital camera  104 . In one embodiment, the digital camera  104  has a limited command set which supports the activities required to capture still and video images and to adjust parameters which control the exposure. Any information captured is recorded in a non-volatile memory such as a flash miniature card  406  within the digital camera  104 .  
         [0035]    Otherwise, if a VBUS signal  210  is not detected by the VBUS signal checker  500 , then the digital camera  104  is in portable mode. In a hand carry portable mode, the digital camera  104  operates by responding to depressions of various buttons that are accessible on the external body of the digital camera  104  as is well known in the art.  
         [0036]    [0036]FIG. 6 illustrates an exemplary state machine of the present invention. In portable mode, the digital camera  104  functions as a still camera that is capable of recording images to a non-volatile memory. The images are saved by the digital camera  104  until they can be read by a host computer system  100  when the digital camera  104  becomes tethered to the host computer system  100  by the USB serial ports  107  and  108 . The method by which a digital camera saves captured images is well known in the art. Operations are initiated by depressing buttons on the digital camera  104 &#39;s external body.  
         [0037]    When USB connectivity is detected by the present invention, the camera manager  501  transitions from state  601  to tethered mode in state  602 . The tethered mode manager  504  polls the USB serial port  107  for incoming commands issued by the host computer system  100 .  
         [0038]    In one embodiment, the commands require the digital camera  104  to perform operations including but not limited to reading the stored images from a non-volatile memory, deleting or releasing the stored images from non-volatile memory, capturing a live picture from a sensor  302  and forwarding the captured image to the host computer system  100  via the USB serial ports  107  and  108  and begin streaming video. Streaming video refers to the continuous capture and transmission of images from a digital camera to the host computer system and is well known in the art. The command operations are processed in state  603 .  
         [0039]    While the commands are being processed in state  603 , the camera manager  501  continues to poll the USB serial port  107  for live VBUS signal  210 . While the VBUS signal  210  is being provided by the USB serial port  107 , the state remains in the tethered mode  602  and the command operation state  603 . If the VBUS signal  210  is discontinued, then camera manager  501  transitions to portable mode state  604  in which button presses are detected on the buttons of the exterior body of the digital camera  104 . The button operations are processed in state  605 .  
         [0040]    [0040]FIG. 7 is a flow diagram illustrating the general steps followed by the present invention. In step  701 , VBUS signal checker  500  of the camera manager  501  periodically polls the software readable register  207  for VBUS connectivity. In step  702 , while the VBUS signal  210  is turned off, the digital camera  104  is in portable mode. In step  703 , in the portable mode, the digital camera  104  functions as a still camera capable of recording images to an non-volatile memory. In step  704 , the camera manager  501  saves captured images until they can be read by the host computer system  100  in the tethered mode. The operations to be performed by the digital camera  104  in portable mode are initiated by depressing buttons on the digital camera  104  body.  
         [0041]    In step  705 , if a VBUS signal  210  is turned on, then the digital camera  104  is in tethered mode. In step  706 , in the tethered mode, the camera manager  501  continues to poll the USB serial port  107  to detect USB connectivity while accepting operation commands from the host computer system  100  through the USB serial port  107 . In this way, the digital camera  104  of the present invention supports automatic transition between tethered mode and portable mode for a digital camera without the need for user intervention.  
         [0042]    What has been described is a method and apparatus to automatically control the behavior of a digital camera by detecting connectivity to a universal serial bus (USB) coupling to a host computer system. More specifically, the control of the dual mode operation to support both portable and tethered mode functionality is predicated by the present invention detecting USB serial port connectivity to a host computer system. The use of a VBUS signal to control the digital camera&#39;s behavior removes the need for having an extra user selectable switch to select a functional mode.  
         [0043]    While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.