CMOS vrs CCD

Discussion in 'Computer Support' started by Charlie, May 4, 2005.

  1. Charlie

    Charlie Guest

    I am looking for a webcam to do video conferencing. Which would be a
    better choice CMOS or CCD. There seems to be very little difference in
    price.

    Thanks
    Charlie
     
    Charlie, May 4, 2005
    #1
    1. Advertisements

  2. Charlie

    pcbutts1 Guest

    Neither is categorically superior to the other, although vendors selling
    only one technology often claim otherwise. The choice depends far more on
    the application...and the vendor.
    Both types of imagers convert light into electric charge and process it into
    electronic signals. In a CCD sensor, every pixel's charge is transferred
    through a very limited number (often one) of output nodes to be converted to
    voltage, buffered, and sent off-chip as an analog signal. All of the pixel
    can be devoted to light capture, and the output's uniformity (a key factor
    in image quality) is high. In a CMOS sensor, each pixel has its own
    charge-to-voltage conversion, and the sensor often also includes
    digitization circuits, so that the chip outputs digital bits. These other
    functions reduce the area available for light capture, and with each pixel
    doing its own conversion, uniformity is lower. But the chip requires less
    off-chip circuitry for basic operation. (For more details on device
    architecture and operation, see "CCD vs. CMOS: Facts and Fiction" (385k
    PDF).)

    CCDs have been the dominant solid-state imagers since the 1970s, primarily
    because CCDs gave far superior images with the fabrication technology
    available. CMOS image sensors required more uniformity and smaller features
    than silicon wafer foundries could deliver at the time. DALSA founder and
    CEO Dr. Savvas Chamberlain was a pioneer in developing both technologies in
    the 1960s, and his leadership helped bring CCD technology forward. Only
    recently has semiconductor fabrication advanced to the point that CMOS image
    sensors can be useful and cost-effective in some mid-performance imaging
    applications.

    CCDs offer superior image performance (as measured in quantum efficiency and
    noise), and flexibility at the expense of system size. They continue to rule
    in the applications that demand the highest image quality, such as most
    industrial, scientific, and medical applications.

    CMOS imagers offer more integration (more functions on the chip), lower
    power dissipation (at the chip level), and smaller system size at the
    expense of image quality and flexibility. They are well-suited to
    high-volume, space-constrained applications where image quality is not
    paramount, such as security cameras, PC peripherals, toys, fax machines, and
    some automotive applications.

    Costs are similar at the chip level. Early CMOS proponents claimed CMOS
    imagers would be much cheaper because they could be produced on the same
    high-volume wafer processing lines as mainstream logic or memory chips. This
    has not been the case. The accommodations required for good imaging
    perfomance have limited CMOS imagers to specialized, lower-volume
    mixed-signal fabrication processes. CMOS imagers also require more silicon
    per pixel. CMOS cameras may require fewer components and less power, but
    they may also require post-processing circuits to compensate for the lower
    image quality.

    The larger issue around pricing is sustainability. Since many CMOS start-ups
    pursue high-volume, commodity applications from a small base of business,
    they must price below costs to win business. For some, the risk will pay off
    and their volumes will provide enough margin for viability. But others will
    have to raise their prices, while still others will go out of business
    entirely. High-risk startups can be interesting to venture capitalists, but
    imager customers require long-term stability and support.

    The money and attention concentrated on CMOS imagers means that their
    performance will continue to improve, eventually blurring the line between
    CCD and CMOS image quality. But for the forseeable future, CCDs and CMOS
    will remain complementary. Each can provide benefits that the other cannot.
    DALSA's approach is "technology-neutral": we are one of the few vendors able
    to offer real solutions with both CCDs and CMOS.

    More info here http://www.dalsa.com/markets/ccd_vs_cmos.asp


    --


    The best live web video on the internet http://www.seedsv.com/webdemo.htm
    Sharpvision simply the best http://www.seedsv.com
     
    pcbutts1, May 4, 2005
    #2
    1. Advertisements

  3. Charlie

    Parko Guest

    Charlie wrote with a thumbnail dipped in tar:
    CMOS based cameras should be cheaper to manufacture due to economies of
    scale. Every MB has a CMOS chip, remember.
     
    Parko, May 4, 2005
    #3
  4. Charlie

    chuck Guest

    honey get logitech zoom or black-n silver they r the best good
    luck...logitech works great on x.p home
     
    chuck, May 8, 2005
    #4
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.