Low-cost snapshots: Dismembering a diminutive digicam
By Brian Dipert, Senior Technical Editor -- 6/12/2008
Buy any digital camera (or computer), and get $70 back when you simultaneously purchase one of 11 available models of inkjet printers or multifunction units. That's the gist of the promotion Epson was running with Buy.com earlier this year. And what gear did I buy, with Prying Eyes analysis in mind? The lowest-priced possible option, of course; Argus's $9.99 DCM-099 0.3M-pixel digicam. What's inside the unit's petite silver plastic case, and do its picture-taking abilities belie my price-defined modest expectations?
As usual, figuring out how to crack open the case (without simultaneously obliterating everything inside) was the hardest step in this project. However, after scratching my head for 15 minutes, I jimmied off the circular black piece of plastic on the unit's front face and, underneath, spied the head of a solitary, small Philips screw. Removing it, then pulling away the camera back panel, exposed one side of the PCB.
Cost is everything with an item whose retail price tag is this low; even fractions of a penny worth of incremental bill-of-materials burden can mean the difference between profit and loss. On that note, I'm not sure why Argus chose to put a vertical strip of black electrical tape along the left side of the PCB; is the fact that the camera's sensor is in the exact same location on the PCB's other side coincidental or meaningful? Similarly, I don't know why there's a small piece of white tape underneath the capacitor in the PCB's upper left corner. The inspection sticker is another curious inclusion.
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Speaking of cost, note the unit's crude pop-up viewfinder, which as it turns out is useful for subject framing purposes. And further on the bill-of-materials-cost topic, note that the camera comes bundled with a software disc (including drivers and an OEM version of an ArcSoft image-processing program), paper documentation (notably comprehensive, and with a notable lack of typographical errors), a wrist strap and case, a AAA battery, and a USB interface cable with a proprietary connector (a baffling choice on Argus' part).
A simple piezoelectric speaker beeps to alert the user of camera power-on-and-off and mode transitions, along with image-capture completion. Underneath it (and a piece of intermediary double-sided adhesive foam) is what I first assumed to be a 2-Mbyte NAND flash memory chip. Googling the item's "ESMT M12L616A" part number, however, alerted me that I had a 16-Mbit SDRAM on my hands. Don't remove the single AAA battery or allow it to drain prior to PC transfer, or you'll lose your stored pictures (yes, I personally confirmed this shortcoming)!
The lack of any visible memory IC save the PSOP-encapsulated SDRAM suggests that system code resides on the same sliver(s) of silicon that implement(s) the camera's "brains." Speaking of encapsulation, the chip-on-board system processor likely can be found under the blob of black epoxy in the center of the PCB. Its specifics are unknown.
Remove two more tiny Philips screws, detach the assembly from the front-panel plastics, and the other side of the PCB becomes visible. Two membrane switches (one to activate the shutter, the other for mode toggling and selection) implement the entirety of user input. As for user feedback (such as remaining-picture count), a low-resolution monochrome LCD, connected to the PCB (as was the case with a prior Prying Eyes adventure) via "zebra strip" elastomers, does this particular deed. There's no post-capture native picture playback on this camera!This design's perfect for exemplifying Moore's Law's strengths and limitations. The amount of double-sided PCB surface area consumed by digital logic and memory circuits (including their packages, which substantially contribute to the total) is only around 20% of the total available real estate. Conversely, discrete capacitors, diodes, inductors, and resistors (and resistor packs) dominate the topology, along with a few power transistors.
A lens labeled as having a F2.6 fixed aperture and 5.4 mm fixed focal length (along with fixed focus) handles incoming photon collection. Underneath it is a VGA-resolution (640×480 pixel) sensor, of unknown dimensions (thereby precluding me from making a lens-focal-length translation calculation to the 35-mm camera equivalent), which I strongly suspect is CMOS-implemented, and which I also strongly suspect contains the intelligence necessary to tackle JPEG conversion and other image-processing functions (which, surprisingly on such a low-end unit, include 50-vs-60 Hz control to compensate for fluorescent bulb illumination situations in countries with varying AC mains power frequencies).
The DCM-099 captures still pictures in both high (VGA) and low (likely QVGA) resolutions, and at two different quality-versus-size compression ratio options, translating to peak resident storage of between 26 and 208 images. It even supports the capture of 6-fps AVI video streams, of unknown resolution (but probably QVGA), and again probably via the motion-JPEG codec.
And how's the unit's image quality? Frankly, I don't know, thereby explaining mu use of "probably" and "likely" above. The software comes on a mini CD that's dimension-incompatible with my MacBook's slot-loading optical drive. Downloading and installing the Windows TWAIN drivers from the support area of Argus's website was an equally unrewarding effort; none of the Windows XP SP2-based computers I subsequently tried connecting to the DCM-099 was able to communicate with it. Given that support costs can also make or break a company's profit aspirations, and that Argus offers a toll-free customer service telephone number (which, I was happy to experience, was promptly picked up by a fairly competent human being, albeit one who was ultimately unable to solve my installation woes), my stumbles don't bode well for Argus' fortunes. Not to mention the fact that software support for OS X or other non-Windows operating systems is unavailable.
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