Abstract:
A timer module is arranged to be mechanically and electronically coupled to a digital image capture camera module and one or more memory modules. A method of operating the timer module includes initially querying the one or more memory modules to determine available memory storage locations. Once the available memory locations are determined the timer module instructs the image capture module to capture images and transfer them to the memory modules a number of times on the basis of the available digital image storage locations. The elapsed time between the image captures may be set as desired by a user of the module.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   The present application is a Continuation of U.S. application Ser. No. 10/636,276 filed on Aug. 8, 2003, now issued U.S. Pat. No. 7,286,182, which is a Divisional of U.S. application Ser. No. 09/575,137 filed on May 23, 2000, now issued U.S. Pat. No. 6,903,766. 

   FIELD OF THE INVENTION 
   The invention relates to a timer module useful in a digital imaging system. It is useful for controlling image capture by a digital image sensor or camera. The timer module finds particular application in a compact printer system able to print full-color, business card size documents from a device about the size of a pen. 
   Australian Provisional Patent Application number PQ0560 dated 25 May 1999. The co-pending applications describe related modules and methods for implementing the compact printer system. The co-pending applications are as follows: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               USSN or 
                 
             
             
                 
               Patent 
             
             
                 
               Number 
               Title 
             
             
                 
                 
             
           
           
             
                 
               6,924,907 
               Compact Color Printer Module 
             
             
                 
               6,712,452 
               Modular Compact Printer System 
             
             
                 
               6,416,160 
               Nozzle Capping Mechanism 
             
             
                 
               6,238,043 
               Ink Cartridge for Compact Printer System 
             
             
                 
               6,958,826 
               Controller for Printer Module 
             
             
                 
               6,812,972 
               Camera Module for Compact Printer System 
             
             
                 
               09/575,157 
               Image Processor for Camera Module 
             
             
                 
               6,554,459 
               Memory Module for Compact Printer System 
             
             
                 
               6,967,741 
               Effects Module for Compact Printer System 
             
             
                 
               6,956,669 
               Effects Processor for Effects Module 
             
             
                 
               6,804,026 
               Color Conversion Method for Compact Printer 
             
             
                 
                 
               System 
             
             
                 
               7,259,889 
               Method and Apparatus of Dithering 
             
             
                 
               6,975,429 
               Method and Apparatus of Image Conversion 
             
             
                 
                 
             
           
        
       
     
   
   BACKGROUND OF THE INVENTION 
   Microelectronic manufacturing techniques have led to the miniaturization of numerous devices. Mobile phones, personal digital assistant devices, and digital cameras are very common examples of the miniaturization trend. 
   One device that has not seen the advantage of microelectronic manufacturing techniques is the printer. Commercially available printers are large compared to many of the devices they could support. For instance, it is impractical to carry a color printer for the purpose of instantly printing photographs taken with known compact digital cameras. 
   A compact printhead has been described in co-pending United States patent applications filed simultaneously to the present application and hereby incorporated by cross reference: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               USSN or 
                 
             
             
                 
               Patent 
             
             
                 
               Number 
               Title 
             
             
                 
                 
             
           
           
             
                 
               09/575,152 
               Fluidic seal for an ink jet nozzle assembly 
             
             
                 
               6,428,133 
               Ink jet printhead having a moving nozzle 
             
             
                 
                 
               with an externally arranged actuator 
             
             
                 
               6,526,658 
               Method of manufacture of an ink jet 
             
             
                 
                 
               printhead having a moving nozzle with an 
             
             
                 
                 
               externally arranged actuator 
             
             
                 
               09/575,176 
               Ink jet printhead nozzle array 
             
             
                 
               6,390,591 
               Nozzle guard for an ink jet printhead 
             
             
                 
                 
             
           
        
       
     
   
   Some cameras have self-timers that allow a user time to move into frame before a photo is taken. Self-timers are only useful for capturing a single image. Some cameras also have the facility for taking multiple frames but this generally requires the user to maintain pressure on a ‘take’ button. In any event, the timers are built in to the camera and have fixed functionality. 
   SUMMARY OF THE INVENTION 
   In one form, the invention resides in a timer module comprising: 
   a body; 
   control means within said body that automates the capture of multiple images by a camera module, the capture of each image being separated by a specific time interval; 
   at least one connection means incorporated in said body for connecting said timer module to a bus providing power and data between said timer module and said camera module. 
   In a further form the invention resides in a timer module for a compact printer system comprising: 
   a body; 
   control means within said body that automates the capture of multiple images by a connected camera module, the capture of each image being separated by a specific time interval; 
   at least one connection means incorporated in said body for connecting said effects module to a bus providing power and data between said effects module and said camera module. 
   In a still further form the invention resides in a method of automating the capture of multiple images by a camera module in a compact printer system comprising the steps of:
     setting a specific time interval between said capture of said images,   setting an initial image number on a connected memory module,   starting said image capture process.   

   Further features of the invention will be evident from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to assist with describing preferred embodiments of the invention, reference will be made to the following figures in which: 
       FIG. 1  is a printer module; 
       FIG. 2  is a camera module; 
       FIG. 3  is a memory module; 
       FIG. 4  is a communication module; 
       FIG. 5  is a flash module; 
       FIG. 6  is a timer module; 
       FIG. 7  is a laser module; 
       FIG. 8  is an effects module; 
       FIG. 9  is a characters module; 
       FIG. 10  is an adaptor module; 
       FIG. 11  is a pen module; 
       FIG. 12  is a dispenser module; 
       FIG. 13  is a first compact printer configuration; 
       FIG. 14  is a second compact printer configuration; 
       FIG. 15  is a third compact printer configuration; 
       FIG. 16  is a fourth compact printer configuration; 
       FIG. 17  is a perspective view of the timer module; 
       FIG. 18  is an exploded view of the timer module; and 
       FIG. 19  is a block schematic diagram of a processor for the timer module. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The invention is described in terms of the application to a compact printer system. It will be understood that the invention is not limited to this particular application but rather can be employed with any digital imaging system. Nonetheless, the compact printer system provides a convenient environment in which to describe the details of the timer module invention. 
   Referring to  FIGS. 1 to 12 , there are shown various modules that together form a compact printer system. Individual modules can be attached and detached from the compact printer configuration to allow a user-definable solution to business-card sized printing. Images can also be transferred from one compact printer to another without the use of a secondary computer system. Modules have a minimal user-interface to allow straightforward interaction. 
   A compact printer system configuration consists of a number of compact printer modules connected together. Each compact printer module has a function that contributes to the overall functionality of the particular compact printer configuration. Each compact printer module is typically shaped like part of a pen, physically connecting with other compact printer modules to form the complete pen-shaped device. The length of the compact printer device depends on the number and type of compact printer modules connected. The functionality of a compact printer configuration depends on the compact printer modules in the given configuration. 
   The compact printer modules connect both physically and logically. The physical connection allows modules to be connected in any order, and the logical connection is taken care of by the compact printer Serial Bus—a bus that provides power, allows the modules to self configure and provides for the transfer of data. 
   In terms of physical connection, most compact printer modules consist of a central body, a male connector at one end, and a female connector at the other. Since most modules have both a male and female connector, the modules can typically be connected in any order. Certain modules only have a male or a female connector, but this is determined by the function of the module. Adaptor modules allow these single-connector modules to be connected at either end of a given compact printer configuration. 
   A four wire physical connection between all the compact printer modules provides the logical connection between them in the form of the compact printer Serial Bus. The compact printer Serial Bus provides power to each module, and provides the means by which data is transferred between modules. Importantly, the compact printer Serial Bus and accompanying protocol provides the means by which the compact printer system auto-configures, reducing the user-interface burden on the end-user. 
   Compact printer modules can be grouped into three types:
         image processing modules including a Printer Module ( FIG. 1 ), a Camera Module ( FIG. 2 ), and a Memory Module ( FIG. 3 ). Image processing modules are primarily what sets the compact printer system apart from other pen-like devices. Image processing modules capture, print, store or manipulate photographic images;   housekeeping modules including an Adapter Module ( FIG. 10 ), an Effects Module ( FIG. 8 ), a Communications Module ( FIG. 4 ), and a Timer Module ( FIG. 6 ). Housekeeping modules provide services to other modules or extended functionality to other modules; and   isolated modules including a Pen Module ( FIG. 11 ) and a Laser Module ( FIG. 7 ). Isolated modules are those that attach to the compact printer system but are completely independent of any other module. They do not necessarily require power, and may even provide their own power. Isolated Modules are defined because the functionality they provide is typically incorporated into other pen-like devices.       

   Although housekeeping modules and isolated modules are useful components in a compact printer system, they are extras in a system dedicated to image processing and photographic manipulation. Life size (1:1) illustrations of the compact printer modules are shown in  FIGS. 1 to 12 , and example configurations produced by connecting various modules together are shown in  FIGS. 13 to 16 . 
     FIG. 1  shows a printer module that incorporates a compact printhead described in co-pending United States patent applications listed in the Background section of this application, incorporated herewith by reference, and referred to herewith as a Memjet printhead. The Memjet printhead is a drop-on-demand 1600 dpi inkjet printer that produces bi-level dots in up to 4 colors to produce a printed page of a particular width. Since the printhead prints dots at 1600 dpi, each dot is approximately 22.5 μm in diameter, and spaced 15.875 μm apart. Because the printing is bi-level, the input image should be dithered or error-diffused for best results. Typically a Memjet printhead for a particular application is page-width. This enables the printhead to be stationary and allows the paper to move past the printhead. A Memjet printhead is composed of a number of identical ½ inch Memjet segments. 
   The printer module  10  comprises a body  11  housing the Memjet printhead. Power is supplied by a three volt battery housed in battery compartment  12 . The printhead is activated to commence printing when a business card (or similar sized printable media) is inserted into slot  13 . Male connector  14  and female connector  15  facilitate connection of other modules to the printer module  10 . 
     FIG. 2  shows a camera module  20 . The camera module provides a point-and-shoot camera component to the compact printer system as a means of capturing images. The camera module comprises a body  21  having a female connector  22 . A lens  23  directs an image to an image sensor and specialized image processing chip within the camera  24 . A conventional view finder  25  is provided as well as a lens cap  26 . An image is captured when the Take button  27  is pushed. Captured images are transferred to the Printer Module  10  for subsequent printing, manipulation, or storage. The Camera Module also contains a self-timer mode similar to that found on regular cameras. 
     FIG. 3  shows a Memory Module  30  comprising a body  31 , LCD  32 , IN button  33 , OUT button  34  and SELECT button  35 . The Memory Module  30  is a standard module used for storing photographic images captured by the Camera  20 . The memory module stores  48  images, each of which can be accessed either at full resolution or at thumbnail resolution. Full resolution provides read and write access to individual images, and thumbnail resolution provides read access to 16 images at once in thumbnail form. 
   The Memory Module  30  attaches to other modules via a female connector  36  or male connector  37 . The male and female connectors allow the module to be connected at either end of a configuration. Power may be provided from the Printer Module  10  via the Serial Bus or from another source, such as a separate power module. 
   A Communications Module  40  is shown in  FIG. 4 . The communications module  40  consists of a connector  41  and a cable  42  that terminates in an appropriate connector for a computer port, such as a USB port, RS232 serial port or parallel port. The Communications Module  40  allows the compact printer system to be connected to a computer. When so connected, images can be transferred between the computer and the various modules of the compact printer system. The communications module allows captured images to be downloaded to the computer, and new images for printing to be uploaded into the printer module  10  and the memory module  30 . 
   A Flash Module  50  is shown in  FIG. 5 . The Flash Module  50  is used to generate a flash with flash cell  51  when taking photographs with the Camera Module  20 . The Flash Module attaches to other modules via female connector  52  and male connector  53 . It contains its own power source. The Flash Module is automatically selected by the Camera Module when required. A simple switch allows the Flash Module to be explicitly turned off to maximize battery life. 
     FIG. 6  shows a Timer Module  60  that is used to automate the taking of multiple photos with the Camera Module  20 , each photo separated by a specific time interval. The captured photos are stored in Memory Module  30 . Any flash requirements are handled by the Camera Module  20 , and can therefore be ignored by the Timer Module. The Timer Module  60  consists of a body  61  housing an optional LCD  62 , START/STOP button  63  and UNITS button  64 . The LCD is optional since data from the Timer Module could be sent on the serial bus to a specific display module. Nonetheless, it is convenient to consider the LCD as part of the Timer Module. 
   A SELECT button  65  allows the user to select time units and the number of units are set by UNITS button  64 . The Timer Module  60  includes a male connector  66  and female connector  67 . The Timer Module takes its power from the Printer Module  10  via the Serial Bus or from another source, such as a separate power module. 
   A Laser Module  70  is shown in  FIG. 7 . The Laser Module  70  consists of a body  71  containing a conventional laser pointer operated by button  72 . As the Laser Module is a terminal module it only has one connector, which in the example is a male connector  73 . The Laser Module is an isolated module, in that it does not perform any image capture, storage, or processing. It exists as a functional addition to the compact printer system. It is provided because laser pointer services are typically incorporated into other pen-like devices. The Laser Module contains its own power supply and does not appear as a device on the Serial Bus. 
   The Effects Module shown in  FIG. 8  is an image processing module. It allows a user to select a number of effects and applies them to the current image stored in the Printer Module  10  or memory module  30 . The effects include borders, clip-art, captions, warps, color changes, and painting styles. The Effects Module comprises a body  81  housing custom electronics and a LCD  82 . A CHOOSE button  83  allows a user to choose between a number of different types of effects. A SELECT button  84  allows the user to select one effect from the number of effects of the chosen type. Pressing the APPLY button  85  applies the effect to image stored in the Printer Module  10 . The Effects Module obtains power from the Serial Bus. Male connector  86  and female connector  87  allow the Effects Module to be connected to other compact printer system modules. 
     FIG. 9  shows a Character Module  90  that is a special type of Effects Module (described above) that only contains character clip-art effects of a given topic or genre. Examples include The Simpsons®, Star Wars®, Batman®, and Dilbert® as well as company specific modules for McDonalds® etc. As such it is an image processing module. It consists of a body  91  housing custom electronics and a LCD  92 . SELECT button  93  allows the user to choose the effect that is to be applied with APPLY button  94 . The Character Module obtains power from the Serial Bus through male connector  95  and female connector  96 . 
   The Adaptor Module  100 , shown in  FIG. 10 , is a female/female connector that allows connection between two modules that terminate in male connectors. A male/male connector (not shown) allows connection between two modules that terminate in female connectors. The Adaptor Module is a housekeeping module, in that it facilitates the use of other modules, and does not perform any specific processing of its own. 
   All “through” modules have a male connector at one end, and a female connector at the other end. The modules can therefore be chained together, with each module connected at either end of the chain. However some modules, such as the Laser Module  70 , are terminating modules, and therefore have either a male or female connector only. Such single-connector modules can only be connected at one end of the chain. If two such modules are to be connected at the one time, an Adaptor Module  100  is required. 
     FIG. 11  shows a Pen Module  110  which is a pen in a module form. It is an isolated module in that it attaches to the compact printer system but is completely independent of any other module. It does not consume or require any power. The Pen Module is defined because it is a convenient extension of a pen shaped, pen sized device. It may also come with a cap  111 . The cap may be used to keep terminating connectors clean in the case where the chain ends with a connector rather than a terminating module. 
   To assist with accurately feeding a business card sized print media into slot  13  of the printer module  10 , a dispenser module  120  is provided as shown in  FIG. 12 . The dispenser module  120  comprises a body  121  that holds a store of business card sized print media. A Printer Module  10  locates into socket  122  on the dispenser module  120 . When correctly aligned, a card dispensed from the dispenser module by slider  123  enters slot  13  and is printed. 
   In the sense that a minimum configuration compact printer system must be able to print out photos, a minimum compact printer configuration contains at least a Printer Module  10 . The Printer Module holds a single photographic image that can be printed out via its Memjet printer. It also contains the 3V battery required to power the compact printer system. 
   In this minimum configuration, the user is only able to print out photos. Each time a user inserts a business card  130  into the slot in the Printer Module, the image in the Printer Module is printed onto the card. The same image is printed each time a business card is inserted into the printer. In this minimum configuration there is no way for a user to change the image that is printed. The dispenser module  120  can be used to feed cards  130  into the Printer Module with a minimum of fuss, as shown in  FIG. 13 . 
   By connecting a Camera Module  20  to the minimum configuration compact printer system the user now has an instant printing digital camera in a pen, as shown in  FIG. 14 . The Camera Module  20  provides the mechanism for capturing images and the Printer Module  10  provides the mechanism for printing them out. The battery in the Printer Module provides power for both the camera and the printer. 
   When the user presses the “Take” button  27  on the Camera Module  20 , the image is captured by the camera  24  and transferred to the Printer Module  10 . Each time a business card is inserted into the printer the captured image is printed out. If the user presses “Take” on the Camera Module again, the old image in the Printer Module is replaced by the new image. 
   If the Camera Module is subsequently detached from the compact printer system, the captured image remains in the Printer Module, and can be printed out as many times as desired. The Camera Module is simply there to capture images to be placed in the Printer Module. 
     FIG. 15  shows a further configuration in which a Memory Module  30  is connected to the configuration of  FIG. 14 . In the embodiment of  FIG. 15 , the user has the ability to transfer images between the Printer Module  10  and a storage area contained in the Memory Module  30 . The user selects the image number on the Memory Module, and then either sends that image to the Printer Module (replacing whatever image was already stored there), or brings the current image from the Printer Module to the specified image number in the Memory Module. The Memory Module also provides a way of sending sets of thumbnail images to the Printer Module. 
   Multiple Memory Modules can be included in a given system, extending the number of images that can be stored. A given Memory Module can be disconnected from one compact printer system and connected to another for subsequent image printing. 
   With the Camera Module  20  attached to a Memory Module/Printer Module compact printer system, as shown in  FIG. 15 , the user can “Take” an image with the Camera Module, then transfer it to the specified image number in the Memory Module. The captured images can then be printed out in any order. 
   By connecting a Communications Module  40  to the minimum configuration compact printer system, the user gains the ability to transfer images between a PC and the compact printer system.  FIG. 16  shows the configuration of  FIG. 15  with the addition of a Communications Module  40 . The Communications Module makes the Printer Module  10  and any Memory Modules  30  visible to an external computer system. This allows the download or uploading of images. The communications module also allows computer control of any connected compact printer modules, such as the Camera Module  20 . 
   Each module is visible on the Serial Bus. Each module is self identifying and self-configuring using standard USB protocols. Apart from the standard protocol functions (including identification), there are a number of functions to which each module is also capable of responding. These are outlined in Table 1. Each module also has a number of module-specific functions. These commends allow the modules to be controlled by an external device, such as a personal computer, and by other modules. 
   
     
       
             
           
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Basic Module Functions 
             
           
        
         
             
               Name 
               Description 
             
             
                 
             
             
               GetImageCounts( ) 
               Returns two counts - the number of images 
             
             
                 
               that can be read from the module, and 
             
             
                 
               the number of images that can be written to 
             
             
                 
               the module. This allows read only, write 
             
             
                 
               only, and virtual read only images. 
             
             
               GetCurrentImageNumber 
               If the module has a setting for the image 
             
             
                 
               number, this call returns the current image 
             
             
                 
               number. 
             
             
               GetImageAccessMethods 
               Returns two sets of 8 access bits. 
             
             
                 
               The first set represents the read access bits, 
             
             
                 
               and the second set represents the write access 
             
             
                 
               bits. See Table 2 for an interpretation of the 
             
             
                 
               bits. 
             
             
               GetImage(N, Mode) 
               Returns image number N using the 
             
             
                 
               specified 8-bit access mode. See Table 3 for 
             
             
                 
               an interpretation of the access mode bits. 
             
             
               StoreImage(N, Mode) 
               Stores an image at address N using 
             
             
                 
               the specified 8-bit access mode. See 
             
             
                 
               Table 3 for an interpretation of the access 
             
             
                 
               mode bits. 
             
             
               TransferImage(N1, Mode, 
               Transfers the image at address N1 using 
             
             
               Dest, N2) 
               the specified 8-bit access mode to the 
             
             
                 
               image at address N2 at the serial device 
             
             
                 
               with id Dest. See Table 3 for an 
             
             
                 
               interpretation of the access mode bits. 
             
             
                 
             
           
        
       
     
   
   The 8-bit mode returned by GetImageAccessMethods is interpreted as follows: 
   
     
       
             
           
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
               8-bit return code from GetImageAccessMethods 
             
           
        
         
             
               Bit 
               Interpretation 
             
             
                 
             
             
               0 
               Access 850 × 534 permitted 
             
             
               1 
               Access 534 × 850 permitted 
             
             
               2 
               Interleaved L*a*b* permitted 
             
             
               3 
               Planar L*, a*, b* permitted 
             
             
               4-7 
               Reserved, and 0 
             
             
                 
             
           
        
       
     
   
   The 8-bit mode used for image read and write access via GetImage, StoreImage and TransferImage is interpreted as follows: 
   
     
       
             
           
             
             
           
         
             
               TABLE 3 
             
           
           
             
                 
             
             
               8-bit code used for read &amp; write access 
             
           
        
         
             
               Bit 
               Interpretation 
             
             
                 
             
             
               0 
               Orientation: 0 = 850 × 534, 1 = 534 × 850 
             
             
               1 
               0 = interleaved, 1 = planar 
             
             
               2-3 
               Color plane (valid only when bit 1 = planar) 
             
             
                 
               00 = L*, 01 = a*, 10 = b*, 11 = reserved 
             
             
               4-7 
               Reserved, and 0 
             
             
                 
             
           
        
       
     
   
   In some situations, certain modules may be configured without the printer module. For example, it may be convenient to configure a camera module  20  and a memory module  30  for capturing and storing images for later printing by the printer module  10 . The timer module  60  and the flash module  50  may be added to the camera module  20  and memory module  30  to produce a digital camera having many of the features of a conventional camera. Additional memory modules can easily be added to provide virtually unlimited memory storage. 
   The above commands allow images to be transferred to and from the modules without going through the printer module. For example, the Memory Module  30  can act under control of the Timer Module  60  to transfer a captured image from the Camera Module  20  to the Memory Module  30  using the TransferImage command. The Camera Module  20  will have a module specific ‘capture’ command for capturing an image. 
   In the general case, the Printer Module holds the “current” image, and the other modules function with respect to this central repository of the current image. The Printer Module is therefore the central location for image interchange in the compact printer system, and the Printer Module provides a service to other modules as specified by user interaction. 
   A given module may act as an image source. It therefore has the ability to transfer an image to the Printer Module. A different module may act as an image store. It therefore has the ability to read the image from the Printer Module. Some modules act as both image store and image source. These modules can both read images from and write images to the Printer Module&#39;s current image. 
   The standard image type has a single conceptual definition. The image definition is derived from the physical attributes of the printhead used in the Printer Module. The printhead is 2 inches wide and prints at 1600 dpi in cyan, magenta and yellow bi-level dots. Consequently a printed image from the compact printer system is 3200 bi-level dots wide. 
   The compact printer system prints on business card sized pages (85 mm×55 mm). Since the printhead is 2 inches wide, the business cards are printed such that 1 line of dots is 2 inches. 2 inches is 50.8 mm, leaving a 2 mm edge on a standard business-card sized page. The length of the image is derived from the same card size with a 2 mm edge. Consequently the printed image length is 81 mm, which equals 5100 1600 dpi dots. The printed area of a page is therefore 81 mm×51 mm, or 5100×3200 dots. 
   To obtain an integral contone to bi-level ratio a contone resolution of 267 ppi (pixels per inch) is chosen. This yields a contone CMY page size of 850×534, and a contone to bi-level ratio of 1:6 in each dimension. This ratio of 1:6 provides no perceived loss of quality since the output image is bi-level. 
   The printhead prints dots in cyan, magenta, and yellow ink. The final output to the printed page must therefore be in the gamut of the printhead and take the attributes of the inks into account. It would at first seem reasonable to use the CMY color space to represent images. However, the printer&#39;s CMY color space does not have a linear response. This is definitely true of pigmented inks, and partially true for dye-based inks. The individual color profile of a particular device (input and output) can vary considerably. Image capture devices (such as digital cameras) typically work in RGB (red green blue) color space, and each sensor will have its own color response characteristics. 
   Consequently, to allow for accurate conversion, as well as to allow for future image sensors, inks, and printers, the CIE L*a*b* color model [CIE, 1986, CIE 15.2 Colorimetry: Technical Report (2 nd  Edition), Commission Internationale De l&#39;Eclairage] is used for the compact printer system. L*a*b* is well defined, perceptually linear, and is a superset of other traditional color spaces (such as CMY, RGB, and HSV). 
   The Printer Module must therefore be capable of converting L*a*b* images to the particular peculiarities of its CMY color space. However, since the compact printer system allows for connectivity to PCs, it is quite reasonable to also allow highly accurate color matching between screen and printer to be performed on the PC. However the printer driver or PC program must output L*a*b*. 
   Each pixel of a compact printer image is therefore represented by 24 bits: 8 bits each of L*, a*, and b*. The total image size is therefore 1,361,700 bytes (850×534×3). 
   Each image processing module is able to access the image stored in the Printer Module. The access is either to read the image from the Printer Module, or to write a new image to the Printer Module. 
   The communications protocol for image access to the Printer Module provides a choice of internal image organization. Images can be accessed either as 850×534 or as 534×850. They can also be accessed in interleaved or planar format. When accessed as interleaved, each pixel in the image is read or written as 24 bits: 8 bits each of L*, a*, b*. When accessed as planar, each of the color planes can be read or written independently. The entire image of L* pixels, a* pixels or b* pixels can be read or written at a time. 
   The Timer Module  60  is used to automate the capture of multiple images with a Camera Module  20 , the capture of each image being separated by a specific time interval. The captured images are stored in an on-line Memory Module  30 . Any flash requirements are handled by the Camera Module  20 , and can therefore be ignored by the Timer Module. 
     FIG. 17  shows a magnified perspective view of the Timer Module  60 , as previously described with reference to  FIG. 6 . The optional LCD  62  provides visual feedback. It contains a 2-digit numerical display  68  representing the number of time units between captured images. Three time units are available: seconds, minutes, and hours, represented by s, m, and h LCD segments respectively. A multi-segment thermometer  69  provides an animated countdown between image captures. As shown in  FIG. 17 , the LCD  62  is showing all segments active. 
     FIG. 18  is an exploded perspective view of the Timer Module  60 . The LCD  62  is mounted on a flexible printed circuit board (PCB)  300 . With reference to  FIG. 19 , also formed on the PCB  300  is a simple microcontroller  351  which is suitably an application specific integrated circuit (ASIC)  350 . 
   In reference to  FIG. 18 , the UNITS button  64  is a double button and operates in the manner of a known rocker switch to increment or decrement the number of time units. Selections made using the UNITS button  64  are communicated to the PCB  300  via contact  301 . 
   The flexible PCB  300  is mounted on a support  303  of chassis molding  302 . In the preferred embodiment the PCB  300  is mounted such that the LCD  62  lies substantially parallel with a front face  304  of the support  303 . The flexible PCB  300  passes over the support such that the ASIC  350  lies substantially parallel with a back face  305  of the support  303 . The flexible PCB  300  passes under the ASIC  350  and extends away from the base  306  of the chassis molding  302 . 
   The contact  301  conforms to a curved edge of the support  303  allowing the base of UNITS button  64  to lie substantially parallel with a side face  310  of the support. 
   The male bayonet connector  66  comprises a cap molding  307 , a latch strip  308  and a plurality of contact strips  309 . The upper end of the cap molding is essentially dome-shaped and comprises two holes  311  positioned diametrically opposite each other. The holes  311  are positioned and shaped to receive the folded ends  312  of latch strip  308 . 
   The lower end of the cap molding  307  comprises an elongated section  313  that is shaped to carry contact strips  309 . The contact strips extend from the upper end of the cap molding, where they form part of the male connector  66 , to the bottom of the elongated section  313 . The bottom of the elongated section fits into a recess  314  in the base  306  of the chassis molding such that the contact strips  309  form part of the female bayonet connector  67 . 
   Raised portions  315  of the contact strips  309  fit into an aperture  316  in the elongated section  313  of the cap molding. Contacts on the flexible PCB  300  mate with the raised portions  315  to make contact with the Serial Bus. 
   The START/STOP button  63  and the SELECT button  65  are incorporated in a molding  317 . A contact in the base of the molding for each button connects with the PCB  300  when one or other of the buttons is pressed. 
   The internal components of the Timer Module  60  are contained within a metal extrusion  318  that comprises a plurality of apertures. It is clear from  FIG. 18  the manner in which the buttons  63 ,  64  and  65 , and the male connector  66  protrude from the extrusion through the associated apertures to perform their function. 
   A fascia molding  319  clips into the aperture  320  and provides a protective cover for the LCD  62 . 
   The Timer Module  60  connects to a compact printer configuration via the male connector  66  or the female connector  67 . Either the male or the female bayonet connector joins the Timer Module to the Serial Bus via contact strips  309 . Power is provided to the Timer Module from the Printer Module  10  via the Serial Bus or from a separate power module. 
   Alternatively, the Timer Module  60  may be connected to a compact printer configuration via both the male and female bayonet connectors. An example of this principle is shown in  FIG. 16  where the Memory Module  30  is connected to the Printer Module  10  via its male connector and is connected to the Communications Module  40  via its female bayonet connector. 
   The Timer Module  60  must be used in conjunction with a Camera Module  20  and at least one Memory Module  30 . The first stage of Timer Module use is therefore to construct a configuration containing at least these Modules. Power may be provided from a power module, a Printer Module  10  or a personal computer through the communications module  40 . However, the Modules may be connected in any order. The Modules are joined together using the bayonet connectors as previously described. 
   The Timer Module queries all the modules in the system to locate the camera module and any number of memory modules. A list is compiled of available memory modules and ranges of available image numbers within those modules. The total number of available image storage locations N is recorded. The timer then instructs the camera N times to capture images and transfer the images to the memory module until all storage locations are full. The timer waits an elapsed time between each image capture. The elapsed time is set by the user using the buttons or commanded from an external source using the timer module command set. The Timer Module commands the transfer of the captured image from the camera module to the memory module using the TransferImage command described above. 
   Once the START button  63  is pressed, the Timer Module  60  counts down the specified time, and then instructs the Camera Module  20  to capture and transfer an image to the appropriate Memory Module  30 . 
   When only a single Memory Module is present in the configuration, after the START button  63  is pressed, the Timer Module continues to capture an image after every time interval has elapsed and transfer each captured image to the single Memory Module until that Memory Module is full. 
   When there are multiple Memory Modules in the configuration, the process is the same as for the single Memory Module, except that the Memory Modules are filled up one by one until all Memory Modules have been filled. The first Memory Module to be written to is the one physically closest to the Camera Module  20 , and the last Memory Module to be written to is the one physically furthest from the Camera Module. 
   Two tasks need to be accomplished before the Timer Module  60  can be activated to begin a countdown. The duration of the time interval between the capture of each image must be set and the initial image number on the Memory Module(s) must be set. These tasks can be performed in any order. 
   The duration of the time interval between the capture of each image is set by selecting the time unit using the SELECT button  65  and then selecting the number of those units using the UNITS button  64 . For example, a time interval of 30 seconds can be accomplished by selecting the seconds units, and then adjusting the number to 30. A time interval of 15 minutes can be accomplished by selecting the minutes units and then adjusting the number to 15. The Timer Unit maintains a context for each unit so as to minimize the change required by the user. 
   Alternatively the duration can be set from a personal computer or another module using the Timer Module command set. 
   The first image to be written to a specific Memory Module will be written to the current image number displayed on that Memory Module. The image number is then incremented. The image number is set by means of the SELECT button  35  on the Memory Module. Setting the initial image number before the Timer Module is activated lets the user specify how many images each Memory Module will capture. For example, setting a 48 image Memory Module to  40  allows the capture of 9 images: images  40 ,  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47 , and  48 . Once the image count reaches 48 it stops and no further images are written to that Memory Module. If multiple Memory Modules are present, the Memory Module next closest to the Camera Module will be written to. 
   Once the two preliminary tasks have been done, the Timer Module&#39;s START/STOP button  63  can be pressed to start the Timer Module. Pressing the START/STOP button  63  a second time stops the Timer Module. While the Timer Module is actively counting down, feedback is given in two ways. Firstly, the time unit LCD segment (s, m or h) flashes on and off (1 second on, 1 second off) to let a user know the countdown is active. Secondly, a multi-segment thermometer  69  provides an animated countdown of the proportion of time elapsed until the next image capture time. 
   As mentioned above, the Timer Module contains an integrated circuit  350 . The elements of the integrated circuit  350  are shown in  FIG. 19 . These elements include a simple microcontroller  351 , a Serial Bus Interface  352 , a small scratch RAM  353  for storing timing instructions and a small program memory  354 . State information is limited to the current time unit setting (seconds, minutes, hours), the number of time units (2-60 seconds, 1-60 minutes, 1-96 hours), whether the timer is active (yes, no), the time until the next image capture (2-60 s, 1-60 m, 1-96 h), the current Camera Module target, the current Memory Module target and the next Memory Module image number. Instructions are limited to setting the time units, setting the number of time units, starting and stopping the timer. 
   Also included in the ASIC is a memory decoder  355  and parallel interface  356  (that communicates with the LCD and various buttons). A Joint Test Action Group unit  357  may be included for self-test purposes. In some circumstances a clock  358  and crystal oscillator  359  may be required. 
   The combination of the Memory Module  30  with a Camera Module  20  constitutes a digital imaging system. This combination allows an image captured by the Camera Module to be stored in the Memory Module. The addition of the Timer Module  60  allows multiple images to be captured and stored automatically. 
   Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention.