Dual purpose camera for VSC with conventional film and digital image capture modules

A dual purpose camera for alternative use with one of photographic film and a digital image capture module is described. The camera includes a camera body, an electrical interface means disposed within said camera body for interfacing the camera body with a digital image capture module; and a communication means disposed within said camera body for transferring data from the digital image capture module to devices external to the camera body.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to image capture. More particularly, the
 present invention relates to a digital image capture module for use in a
 conventional still camera in place of photographic film.
 2. The Prior Art
 Digital cameras which capture and store a series of images as digital
 information using digital image sensing and semiconductor memories are
 known in the art. Examples of such cameras are the Color QuickCam
 available from Connectix, the ePhoto 307 Color digital camera available
 from AGFA, and the DC20, DC25, and DC120 model cameras available from
 Kodak. Instead of employing photographic film which must be chemically
 developed to produce images which are printed on transparencies or
 photographic paper, these cameras operate by focussing an image on a
 semiconductor imaging plane and then storing the image in a semiconductor
 memory in the camera.
 Other digital cameras are available for the professional market and provide
 higher resolution digital images than the consumer digital cameras
 referred to above. These cameras are specially designed and cost in excess
 of several thousand dollars.
 One or more images captured by the camera may be downloaded to a computer
 or other device through a serial or parallel interface provided in the
 camera using software running on the computer or other device. Once
 downloaded to a computer, the images may be displayed on the computer
 display, manipulated and used in documents generated on the computer, and
 even printed onto paper by a printer connected to the computer.
 While such prior-art digital cameras have achieved widespread popularity,
 they are presently limited in several respects. Such limitations include
 lower image quality due to low pixel resolution and inexpensive optics and
 inability to change lenses and aperture settings in the case of the
 consumer digital cameras, and high cost in the case of the professional
 cameras.
 It would be advantageous to employ conventional photographic film cameras
 to capture digital images. If traditional photographic film cameras could
 be so employed, a user could simply convert an existing camera into a
 digital one while taking advantage of the many features which such cameras
 provide, such as better optics, interchangeable lenses, manual aperture
 adjustment, autoexposure settings, etc., while retaining the option of
 using conventional photographic film as well.
 It is therefore an object of the present invention to provide an economical
 digital image capture apparatus which may be used with conventional
 photographic film cameras.
 It is another object of the present invention to provide an economical
 digital image capture apparatus which may be easily used with conventional
 photographic film cameras from which a user can easily download images
 into a personal computer, a printer, a storage device, a display device, a
 docking station, a remote device via a modem or network interface.
 It is a further object of the invention to provide a digital image capture
 apparatus in a package having the form factor of a standard photographic
 film container such as a 35 mm or other form factor cartridge.
 Yet another object of the present invention is to provide a dual use camera
 which may employ conventional photographic film or the digital image
 capture apparatus of the present invention.
 BRIEF DESCRIPTION OF THE INVENTION
 A digital image capture module is provided according to the present
 invention for use with a photographic film camera having a defined
 photographic film format such as 35 mm. The digital image capture module
 of the present invention includes an imaging array having a focal plane,
 the imaging array configured to convert an optical image focused on the
 focal plane to electronic image signals. A digital memory is provided for
 storing image data. Control circuitry communicates with the imaging array
 for converting the electronic image signals into digital image
 information, for writing the digital image information into the digital
 memory, and for reading the digital image information from the digital
 memory onto an interface bus, or a port, such as a serial, parallel, SCSI,
 or Firewire port.
 The digital image capture module of the present invention is disposed in a
 housing having the form factor of a photographic film holder for the
 defined format. The imaging array is electrically connected to and
 physically oriented with respect to the housing of the digital image
 capture module such that when the housing is disposed in a photographic
 film camera having the defined photographic film format, the imaging array
 is positioned at the focal plane of the photographic film camera as if it
 was a frame of photographic film ready to be exposed.
 According to one embodiment of the present invention, a source of
 electrical power for the module comprising one or more batteries is
 located within the housing of the module. In another embodiment of the
 invention, the power source for the module is located elsewhere in the
 camera outside of the housing and is electrically connected to circuitry
 disposed inside the housing.
 According to another embodiment of the invention, a transparent window in
 the camera back is used to optically upload the contents of the module to
 a computer or other electronic device. RF techniques may also be used to
 upload the images. In other embodiments of the invention a specially
 adapted camera back provides controls for the module and a connector
 and/or an optical, infrared, RF window or other means for uploading the
 contents of the module.
 According to another embodiment of the invention, a dual-use camera is
 provided which may either employ standard photographic film or the digital
 image capture apparatus of the present invention. Such a camera provides a
 physical and data interface to the digital image capture apparatus.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
 Those of ordinary skill in the art will realize that the following
 description of the present invention is illustrative only and not in any
 way limiting. Other embodiments of the invention will readily suggest
 themselves to such skilled persons.
 Referring first to FIG. 1 an isometric view of a presently preferred
 embodiment of a digital image capture module according to the invention is
 shown. According to the present invention, the digital image capture
 module is for use with a photographic film camera having a defined
 photographic film format and is used with a regular camera in place of the
 photographic film which would normally be loaded into the camera for
 taking pictures. As will be apparent from an examination of FIG. 1, the
 illustrative embodiment depicted therein is for use with 35 mm format
 cameras, but the present invention is not limited to a digital image
 capture module for a 35 mm camera. From the disclosure herein, persons of
 ordinary skill in the art will readily be enabled to make and use
 embodiments of the present invention for other camera size formats.
 In the embodiment of FIG. 1, the digital image capture module 10 is
 disposed in a housing 12. The illustrative embodiment of the digital image
 capture module of the present invention disclosed herein is designed to be
 the same size(form factor) as a conventional 35 mm film cartridge so that
 it mechanically fits in the space inside a standard 35 mm camera where a
 conventional 35 mm film cartridge is loaded. However, the shape of housing
 may differ from the appearance of the conventional film cartridge--the
 important criteria being that it fits in the same space.
 An imaging array 14, disposed on a flexible member 16 such as a flex
 circuit which also serves to make electrical connections between the
 imaging array 14 and control circuitry disposed within the housing 12,
 extends from the housing 12 in the same way that the end of a roll of
 photographic film would extend from a conventional 35 mm film canister.
 Imaging array 14 is disposed on substrate 16 so as to align with the focal
 plane of the camera when the housing 12 is inserted in the camera and the
 camera back is closed.
 The imaging array 14 may consist of a thin CMOS based image-receptor
 silicon wafer having an area of preferably about 35.times.24 mm, supported
 by a substrate comprising a thin backing material, such as flex circuit
 material or a rigid material. The total thickness of the receptor with the
 backing will be less than about 1.0 mm, so it can be squeezed behind the
 back cover of the camera where the conventional 35 mm frame resides during
 operation. Imaging array 14 may possibly have reinforced corners that snap
 into the camera body at the focal plane of the camera. CMOS imaging arrays
 suitable to be employed in the present invention are known in the art.
 The imaging array 14 may be attached to the main body by means of a
 flexible, hinge-like joint or simply by the flex nature of the
 flex-circuit material itself.
 An auxiliary enclosure may be attached to the distal end of the image array
 14, opposite to the housing, in order to augment the space provided by the
 housing. The auxiliary enclosure holds a battery, memory and/or additional
 circuitry to facilitate or enhance the digital image capture module
 operation. This auxiliary enclosure may be designed to fit in the space
 where the conventional film is attached to the take-up spool. Alternately,
 one or more batteries may be disposed within the housing itself. Some 35
 mm camera models may not have adequate space in their bodies for such an
 auxiliary enclosure.
 From an operational standpoint, the digital image capture module of the
 present invention functions much like the conventional film. Once one or
 more images are captured on the digital image capture module, the image
 information is transferred to a local computing device, a printer, a
 display device, a docking station or a remote location via a modem,
 network or internet connection, etc. Host resident software and
 software/firmware in the digital image capture module is used to control
 the transfer operation. As presently contemplated, a docking station may
 be used in conjunction with the digital image capture module to transfer
 images from the digital image capture module. The docking station also
 facilitates other needs of digital image capture module, such as erasure
 of image data, recharging of its batteries and a safe container. Alternate
 embodiments for transferring image data comprise connecting the digital
 image capture module directly to a serial port, a Firewire port, a
 parallel/SCSI port in a PC, or a high speed modem, etc. Data transfer
 processes and apparatus are well known in the art.
 The main body or housing of the digital image capture module in the
 approximate shape of a conventional 35 mm film cartridge as illustrated in
 FIG. 1 contains all the logic, memory and processing circuitry. It may
 include a small LCD display, showing the current frame counter. The LCD
 display may also be used to indicate the battery level as is known in the
 art. One or more button switches may be available for user functions such
 as reversing and/or resetting the counter, thereby discarding one or more
 previously stored images and changing the resolution of image capture,
 etc. A communications port is built into the base or elsewhere in the main
 body to upload image frames to a computing device locally or remotely.
 Alternatively, as previously indicated, communication may be accomplished
 wirelessly via infrared, RF, etc. An edge connector may be added to
 connect to a capture docking station or other apparatus. A switch is built
 in to sense closure of the camera back cover, to enable operation and
 activate the imaging function.
 A block diagram of illustrative circuitry 30 for the digital image capture
 module is shown in FIG. 3. A CMOS imaging array 32 communicates with a
 memory 34, which may comprise, for example, a DRAM array having a capacity
 of 16 MB, via sensing, digitizing, and compression circuitry 36. Sensing,
 digitizing, and compression circuitry 36 includes the sense amplifiers and
 other related circuitry, such as analog-to-digital converters for
 transferring the image out of the array. In order to improve memory usage,
 compression may be applied to the digital image data in sensing,
 digitizing, and compression circuitry 36. Digital compression techniques
 are well known in the art. A communications interface 38 is employed to
 transfer data from the memory 34 to a computer or other device for
 processing, display, and storage.
 A control circuit 40 directs the operation of the imaging array 32, the
 memory 34, sensing and compression circuitry 36, and communications
 interface 38. As is known in the art, control circuit 40 may comprise a
 CPU, firmware, communications and other logic.
 User interface elements, such as an LCD display 42, one or more input
 switches 44, and other elements, such as a frame advance audible indicator
 46, etc., may be connected to control circuit 40.
 Referring now to FIG. 4, an illustrative flow diagram of the operation of
 the digital image capture module is presented. Persons of ordinary skill
 in the art will recognize that the flow diagram of FIG. 4 is merely
 illustrative and not limiting as to the operation of the digital image
 capture module of the present invention.
 First, at step 50, the system is reset. If the module is in a quiescent
 state, the first shutter release sending light, closing the back cover, or
 other known methods, may trigger an active image capture state. At step
 52, the imaging array is activated and the system loops around step 54
 waiting for the camera shutter to open. This state is referred to
 hereinafter as a "photo session" state in which the imaging array 14 is
 activated. When the camera shutter opens, the image on the focal plane of
 the camera is sensed by the imaging array. When the shutter closes, the
 image is transferred out of the image array at step 56 and compressed and
 stored into the memory at step 58.
 Next, at step 60, the frame count is advanced. If an LCD or other display
 is used, the displayed frame number is updated. At step 62 the count is
 examined. If the frame just stored was not the last frame, control returns
 to step 52, where the imaging array is cleared to await the shutter
 opening for the next frame capture. If the frame just stored was the last
 frame, process control proceeds to step 64, to signify the end of the
 image capture process.
 One approach to sensing opening of the shutter is to provide a fixed
 number, for example, five "always-on" pixels in the imaging array that
 will always be sensing light, including during the quiescent mode (which
 is the idle mode during which all other sensor pixels are inactive,
 awaiting activation of a photo session). These "always-on" pixels are
 preferably uniformly spread across the sensor surface in a manner such
 that when an image is received, likelihood of at least one of them sensing
 light is very high. Thus, the shutter shall be deemed "closed" when none
 of these special pixels simultaneously detect any light.
 The shutter open event will he detected by at least one of the "always-on"
 pixels sensing light, and considered open until shutter closure is
 detected. Subsequently the shutter closure shall be implied by all pixels
 simultaneously sensing no light. Upon shutter closure, digital image
 capture module logic will start a mode timer at the expiration of which
 digital image capture module will return to quiescent mode if no further
 shutter open is detected. Otherwise, if the shutter open event occurs
 prior to mode timer expiration, the photo session will continue.
 As is known in the art, the image capacity of the digital image capture
 module of the present invention depends on memory size, image resolution,
 and image compression. For a given memory size, different resolution
 settings may be provided, resulting in a different number of frames
 possible for different selected resolutions. In an exemplary embodiment of
 the digital image capture module of the present invention where the size
 of the memory is 16 MB, 20 frames at a resolution of 1500.times.1000 using
 256 grey shades may be stored in the memory or 80 frames at a resolution
 of 750.times.500 may be stored in the memory, assuming a compression ratio
 of 2:1.
 Persons of ordinary skill in the art will appreciate that color will reduce
 this capacity. A color imaging array having red (R), green (G), and blue
 (B) pixels employs three times the number of pixel elements as does a grey
 scale imaging array for the same resolution. A simple scheme would be to
 use 3 actual pixels in close proximity to capture the three components R,
 G & B of each light element.
 The following two illustrative schemes enable storage of the three color
 components R, G, and B associated with each pixel element effectively
 using only twice the physical pixel space instead of three times (one for
 each component). Both capitalize on the phenomena that the green component
 of a picture element contains about two third of the light intensity, and
 the red and blue share the remaining third. These schemes, therefore, for
 each actual picture element of an image allocate one green pixel and
 effectively only half pixel each for the other two, thereby using a total
 of two physical pixels to provide the three components. These both employ
 one green pixel for each picture element location, while one red pixel for
 each alternate picture element, effectively using half as many pixels for
 the red component. The same approach is used for the blue pixels.
 According to both schemes, appropriate red, green, and blue optical filters
 are disposed over the imaging array to provide color sensitivity. Use and
 implementation of such filters is known in the art.
 A first approach employs pixel sensing elements in the following order:
 GRGBGRGBGRGBGRG . . .
 RGBGRGBGRGBGRGB . . .
 GBGRGBGRGBGRGBG . . .
 BGRGBGRGBGRGBGR . . .
 Another scheme employs pixel sensing elements in the following order:
 GRGRGRGRGRGRGRG . . .
 BGBGBGBGBGBGBGB . . .
 GRGRGRGRGRGRGRG . . .
 BGBGBGBGBGBGBGB . . .
 While two illustrative color sensing schemes have been disclosed herein,
 persons of ordinary skill in the art will appreciate that other schemes
 may be employed in the present invention.
 The digital image capture module may be inserted into a capture docking
 device or otherwise connected to a computer when captured images need to
 be processed. The capture docking station is designed to provide
 stand-alone processing of the images, or to connect the digital image
 capture module to a PC, a computer network, a printer, a computer display
 screen or a TV. The docking station will typically connect to a PC or
 other device or system through a high speed port such as Firewire, SCSI or
 parallel port as is known in the art.
 When a digital image capture module is removed from its host camera, a
 docking station may be used with the present invention. A docking station
 would provide a safe storage case for ease in handling as well as reduced
 risk of damage by accident, environment and soil by human contact. It will
 facilitate transfer of captured images using wire or wireless schemes and
 provide a means to recharge digital image capture module batteries. Such a
 docking station may also be used for local searching, viewing, editing,
 text and sound annotation, indexing, rearrangement and deletion of images
 by means of a combination of components such as a microphone, a suitable
 display screen, an attachable keyboard and/or a pointing device. The
 docking station could also enable archive/search/retrieval of images from
 a built-in bulk storage device.
 A number of docking station types may be designed by combining one or more
 of the above features, to address user needs in a number of market
 segments. For example, a minimal dock may comprise a simple protective
 case that exposes the communications port on the digital image capture
 module to facilitate connection to an image upload device, as well as
 recharge the batteries. A fully loaded docking station may house a sizable
 bulk storage device, sport a large LCD screen that displays both thumbnail
 size as well as full size images, allows significant editing, image
 processing, text/graphics/sound annotations, etc. In essence, a docking
 station may serve the purpose of a feature rich digital album, obviating
 the need for a host PC altogether for many users.
 When the digital image capture module is loaded in the camera and the back
 cover closed, the user emulates the conventional approach, such as
 advancing the film advance lever a few times to set the film counter to 1.
 This would enable the shutter operation in a typical camera. As a result
 of back cover closure being sensed, the logic in the digital image capture
 module initializes itself to accept new images starting from the current
 frame counter. The frame counter may be reversed at any time by user by
 pressing a button on the digital image capture module to cause its latest
 stored frame to be erased. The same button, if held down, for example, for
 two seconds, will reset the frame counter to 1 and erase all frames. These
 features enable the user to discard selected frames or sequences of frames
 and start again from any specific counter value. Unlike conventional film,
 the user can open the camera back cover at any time to adjust the frame
 counter. The frame counter is also adjustable or resettable to 1 by host
 software during the upload process. Interfaces for such user control are
 well known in the art.
 Once the digital image capture module is loaded in the camera and the
 shutter is pressed, the image is captured by the imaging array, and sent
 to memory. The internal frame counter is advanced to the next empty frame.
 Unlike the conventional film, no physical motion takes place; the imaging
 array remains fixed in the same space.
 The battery logic will keep memory alive at all times. According to a
 presently preferred mode of operation, the imaging array will, however, be
 turned on only when the user is ready to take pictures. As stated earlier,
 the user can indicate this by pressing the shutter once at the start of a
 session or by other known means. No image will be captured and the
 internal frame counter is not advanced by this action. Once a photo
 session begins, the imaging array will stay on for a preset time to allow
 additional pictures during the session. When this time expires, the
 activation process will need to be repeated. Alternatively, opening the
 back cover and closing it will also cause imaging array activation.
 Audible tones may be generated to differentiate between start of a
 session, capture of an image, and end of a session.
 Once digital images are captured on digital image capture module, they need
 to be uploaded, decompressed, color transformed, brightness/contrast
 adjusted, and/or color corrected, etc. before they can be displayed or
 printed. The image may also be subjected to user desired modifications,
 indexing, captioning, editing, cleanup, combining, etc.
 This process is performed within a desktop PC, a network PC (or an NC), or
 another suitable device, such as a specially designed docking station
 discussed elsewhere in this document, by means of software utilities or
 applications as is known in the art. Examples of such off-the-shelf
 products would be, Hotshot from PictureWorks, PhotoDeluxe from Adobe,
 MyQuickTakeApp from Apple Computer, etc. Typically, a basic set of
 features would be included within a software utility packaged with digital
 image capture module. The user may then optionally acquire additional
 functionality by off-the-shelf upgrade from a retailer, or an application
 directly from a manufacturer.
 According to another embodiment of the present invention, a dual purpose
 camera is provided. The dual purpose camera of the present invention can
 be used either with conventional photographic film or with the digital
 image capture module of the present invention. An illustrative embodiment
 of such a dual purpose camera is illustrated in FIGS. 5 and 6.
 FIG. 5 is a perspective view of an illustrative embodiment of a dual
 purpose camera 70 according to the present invention showing several of
 its features.
 FIG. 6 is a rear view of an illustrative embodiment of the dual purpose
 camera 70 according to the present invention showing several other ones of
 its features.
 For a dual-purpose camera according to the present invention, a special
 somewhat simpler and less costly version of the digital image capture
 module of the present invention is contemplated. This digital image
 capture module of the present invention would utilize internal camera
 battery and the film counter (plus battery level) display built into the
 camera body. Electrical contact between the digital image capture module
 and the host camera may be made as is conventional in the electronics art
 by use of electrical contacts or connectors which provide mating
 electrical connections between the digital image capture module and the
 camera body.
 In addition, as shown in FIG. 5, such a camera 70 would include a
 communications port which may comprise an RJ-11 or similar connector 72 or
 other communications port connector 74. The communications port allows
 image data to be uploaded from the digital image capture module for use by
 a computer or other viewing device as previously described herein. In
 addition, a hinged cover 76 on the camera body may be opened to expose an
 edge connector 78 for connection of the camera 70 to a docking station for
 uploading, storing, editing, and/or viewing captured images.
 Employing a communications port on the camera body eliminates the need for
 pulling out the digital image capture module cartridge for the upload
 purpose, reducing the chores and risk of handling. The camera can also be
 designed to house a short length of a built-in communication cable that
 directly connects to a PC, or modem etc. The camera may also be designed
 with a wireless (infrared, RF, microwave, etc.) transmitter/receiver for
 exchanging image data with a suitably located host device. Such systems
 are known in the art.
 A microphone 80 and associated circuitry may be added to the camera to
 enable sound annotation or live sound capture onto a digital image as is
 known in the art.
 A socket 82 (FIG. 6) may be provided for a bulk storage device such as a
 tiny hard disc, a PCMCIA slot or a flash memory module insertable into the
 camera body or its back to increase the frame storage capacity of the
 digital image capture module significantly. This feature has the potential
 of facilitating longer sequences of animation at, for example, a sports
 event, or even enable a limited video capability with much higher image
 quality than typical today. Such storage would also require additional
 battery power, which would need to be incorporated into the camera.
 By locating control buttons and film counter display on the camera body,
 digital image capture module package would be simplified, thereby
 enhancing user convenience as well as reducing the cartridge cost.
 A "deluxe" version of the camera may sport a back with a built-in digital
 image capture module sensor, logic and memory, so as to allow installation
 of a conventional film to supersede the digital operation, without having
 to remove the digital image capture module components. Thus, the camera
 acts as a digital device without the conventional film, and as a
 conventional camera when the conventional film is installed (the digital
 sensor having been slightly adjusted manually or automatically and shield
 protected to prevent damage from film movement to accommodate the normal
 film), the camera switching to the conventional mode when such a film is
 sensed.
 A sizable LCD display 84 including frame number and date and time
 indicators as shown may be provided on the camera back 86. It could also
 be used to add text or graphic captions, or an indexing scheme to
 facilitate searching for an image. Control buttons 88a, 88b, 88c or
 optional touch input on LCD display are used to control the LCD display
 and may provide features such as image search/selection, rearrangement,
 date and time programming, enable/disable of date and time display,
 captions, etc. In addition, control buttons, 90a, 90b, 90c for the digital
 image capture module can allow control of features such as image erase,
 bulk erase, frame advance, indexing, backup, etc. Control interfaces for
 such functions are well understood in the art.
 Additional information such as underexposure/ overexposure lighting
 conditions, background lighting, use of flash, filters, special lenses
 systems etc. from the camera may be appended to a digital image for an
 automatic compensation by software for these conditions when image is
 eventually processed for viewing or printing.
 The dual-purpose camera according to this aspect of the invention
 eliminates the need for pressing shutter to start a photo session because
 turning the camera power on will simultaneously activate the power to the
 digital sensor.
 While embodiments and applications of this invention have been shown and
 described, it would be apparent to those skilled in the art that many more
 modifications than mentioned above are possible without departing from the
 inventive concepts disclosed herein. The invention, therefore, is not to
 be restricted except in the spirit of the appended claims.