Unknown LCD Display

Discussion in 'Electronics Resources' started by freshestf, Apr 24, 2012.

  1. freshestf

    freshestf Thread Starter New Member

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    I'm working on an Arduino thermometer project and received a casing with an unknown LCD display. It has no identification on it whatsoever. I was hoping someone is familiar with the technology and could point me in the right direction to obtain a datasheet for it or at the very least tell me what kind of LCD it is and how it works. The pictures aren't the best, but hopefully they're good enough.

    There are two LEDs, on diagonal corners from one another. A blue rubber strip runs along the top and bottom of the screen (with a black "line" through the middle). When you apply a little pressure to the rubber, the screen responds in what seems to be a random manner. There are no pins or hardware connections from what I can see.

    Attached Files:

  2. nDever

    nDever Member

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    There actually may be a port for an ultra-thin ribbon cable to connect to this display. Because the cable would be extremely thin, the port that it goes in may be difficult to spot at first. Try looking for a slit on the display.

    From your pictures, the display looks like a monochrome model. Do you have any idea where (or from what) the LCD might have come from?
  3. BSomer

    BSomer Member

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    The rubber strips are what pass the signals to the LCD. Usually these make connections to fine pads on a PCB. If you were to remove one from the LCD you may be able to see the connection points on the LCD itself.

    Trying to locate info on an LCD with no identification marks or knowing what it came off of can be near impossible. The reason for this is that there are generic LCDs with just your standard 7 segment digits and then there are custom made ones that have special characters and layouts for specific manufacturers of electronic devices.
  4. freshestf

    freshestf Thread Starter New Member

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    Both responses make perfect sense. However, I don't recall seeing any slits for a ribbon connection (and unfortunately one of my team members has the LCD so I can't inspect it at the moment). I doubt I overlooked it, given the time I spent trying to figure out how it worked. It would make sense that the connections are behind the rubber strips. I'll have to look into this the next time I get my hands on it.

    After posting my thread, I did find the LCD is manufactured by Welch Allyn (the same company that provided the thermometer casings), not a third party as I had assumed. The LCD is used for a medical thermometer, which probably does have special characters and layouts. Unfortunately, Welch Allyn does not share any technical documents with their customers. There's only a very vague service manual which was no help.

    Even if I could find a ribbon cable to fit, I'd probably struggle interfacing with the pins and figuring out the functionality (unless it follows some standard pin layout and such).
  5. BSomer

    BSomer Member

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    It may be better to write this one off and buy or find an LCD that has easily attainable documentation. The Arduino has a lot of functionality with a number of different types of displays. You could even get a graphic display and make up your own characters and symbols with a little animation.

    Its just an idea.
  6. freshestf

    freshestf Thread Starter New Member

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    Yeah, we've already ordered another LCD. The nice thing about the one we were given is it was free and it was designed specifically to fit in the thermometer casings. We couldn't find any other LCD with the same dimensions, so we settled for the closest. Thanks for the insight.
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