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EL Backlight

Discussion in 'Electronic Design' started by James, May 8, 2009.

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  1. James

    James Guest

    Hi All,

    I am looking to backlight a small LCD. It is about watch size, about
    0.5 square inches. I would like to use an EL backlight because it
    looks like they are more efficient then LED. I am power my device
    with a 3 volt CR1216. This is about a 20maH battery. There is not
    much power to spare.

    Is anyone familiar with who manufactures EL drivers for a small
    display like this one?

    I wonder if the watch manufactures do their own drivers or if they are
    using someone driver IC?

    Thanks,
    James
     
  2. linnix

    linnix Guest

    It is very difficult to make EL backlight cost effective in such a
    small size. If you want efficiency, you can drive a watch size OLED
    screen for approximately 5mA full screen. A typical display could be
    20% to 50% or 1mA to 2.5mA effective.
    Which manufacturer? There are standard driver ICs for both LCD and
    OLED displays.
     
  3. Nemo

    Nemo Guest

    I am power my device
    You should certainly avoi LEDs. I once used a much larger coin cell,
    CR2012 I think, to power an instrument. It was the largest coin cell I
    could find which was dual-sourced, and was based on LiMnO2 chemistry.
    All went well at first, but then we found that it could not power our
    piezo alarm sounder and very efficient alarm LED's for very long.
    Basically these cells may be rated at 200mAhr or whatever - but if you
    take more than about 20mA (I forget exactly how much current we were
    using) their internal resistance rises within a few minutes.

    We had to move to a larger, cylindrical battery. Could you use something
    like a CR2 size cell?
     
  4. James

    James Guest

    Nemo,
    I am using a CR1216 and I have found similar things with this
    battery. I am driving a micro and the internal resistance is large
    enough that there is a lot of noise on the battery line. I pull about
    2ma and I think that this is quite a bit for this battery.
    James
     
  5. James

    James Guest

    I will take a look at OLED backlights. It would be great if I could
    get the backlight done for under 5ma. I was under the impression that
    OLED's were primarily used for higher resolution displays. I am using
    a cheap 4 digit 7 segment LCD display. One reason that I am
    interested in an EL backlight is that I did not want to add much
    thickness.

    I have looked at supertex for EL drivers and I was asking if there are
    other EL driver manufactures that I should look at? What about OLED
    drivers, is there a leading manufacture?

    Thanks,
    James
     
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