Whats easier?, moving an LCD or converting to 7-segment LED

Discussion in 'General Electronics Chat' started by SEMguy, Jan 6, 2008.

  1. SEMguy

    Thread Starter New Member

    Jan 5, 2008
    2
    0
    Hello to all.

    This is my first post here, I did a bunch of searches and could not find an answer to my problem, So I am posting here.


    Problem: I have a device ( a digital micrometer ) on it is a small LCD display. the PCB cannot be moved, but I want to remote locate the display and hopefully use a larger one at the same time.

    the LCD display connects to the PCB by a small piece of conductive rubber I have removed the rubber and I can solder wires to each of the contacts to connect to the remote display. There are 19 contacts on the PCB. as of now I do not know the pinouts.

    SO what will be easier? to try and find a larger LCD unit, or convert to LED, I have many 7-segment LED displays in my parts bins, but buying a new LCD is not a problem.

    I figure either way I will have to build a power supply for the remote display because of the size difference and the fact that the Micrometer works off one 1.5v button battery.

    if anyone knows what the pinout on LCDs like this are (I have seen many things that are set up the same way as the Micrometer) that would save me the time of figureing it all out and would be greatly appreciated. even just a rough idea would be great.

    By the way the LCD appears to be 5 digits with a minus sign to the left and a millimeter mark (mm) to the right.

    Thank you in advance and if you have any ideas or thoughts please post I am always open to trying things a different way.

    Thank you
    SEMguy.
     
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    You should really consider moving to a larger LCD display. A LED display needs at least 1.7V and 2mA to be driven properly (that is, to be visible). The chip that is driving your LCD won't give you those levels.

    Movong to a larger LCD display might be difficult, unless the interface (the part that connects) is exacly the same. Otherwise you have to build a PCB board to interface the display (chances are that a new LCD display already has a PCB board and holes to solder connections).

    My advice is not to make any modifications to your device.
     
  3. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Just for clarity, is this a micrometer or a caliper? A lot of people get the two confused!

    For the calipers, I know that a lot of people like to read out the measurement data. There is actually a serial protocol which details current measurement information, then the programmer decodes this and produces their own display. I think there may be readout kits available.

    If my hunch is incorrect, then you may be in for a good amount of work. I'm guessing that the controller is far from standard, but it may just be a simple parallel interface to the LCD. From memory, I don't think you can simply apply voltage to the LCD itself, I think you have to switch it on and off. I think it has something to do with if an electrolysis-like degradational effect.

    LEDs are great readouts for this sort of application. I would highly recommend trying to read the LCD signals, then finding a way to buffer them, then drive the LED in parallel. I'm not really sure what to expect from the LCD signals though, so you would have to do some measurements.

    Steve
     
  4. SEMguy

    Thread Starter New Member

    Jan 5, 2008
    2
    0
    It is a Pair of digital calipers I am trying to modify.

    SEMguy
     
  5. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
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