capacitive touch screens

Discussion in 'The Projects Forum' started by curious_to_know, May 23, 2010.

  1. curious_to_know

    Thread Starter New Member

    Jun 23, 2007
    9
    0
    Hi!
    i am upto something techy this summer. so i am curious_to_know the technical aspects of the capacitive touch screen- the actual capacitance developed, the minimum area of contact and/or the field required...that to if any.

    i made some effort like "googling" but unfortunately got my hand only on the basic working principle without any such technical specifications

    is anyone having such data?
    also is any one aware of the the notion ink adam? any idea if it is using the projected capacitance or the surface capacitance.

    ps: do not post links of wikipedia or howstuffworks ---the don't give the tech data i am looking for.

    thanks
    curious_to_know
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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  3. curious_to_know

    Thread Starter New Member

    Jun 23, 2007
    9
    0
    thanks a lot for the link!

    the specifications mention the circuit voltage requirements i am still unable to find the sensor capacitance requirements.
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    The sensor capacitance requirements differ from manufacturer to manufacturer, you will have to pick a Capacitive Touch IC and look up the specs on that, I have used the MPR084Q Capacitive touch sensor from Freescale Semiconductor, and there are others like it..... Microchip has Microcontrollers for Touch Sensing >>http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en548149

    B. Morse
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    I did a PIC project with free HEX file that measures and displays capacitance down to 0.01pF in 0.01pF resolution;
    http://www.romanblack.com/onesec/CapMeter.htm

    It's ideal for working with capacitance sensors as you can connect it to your pad prototypes etc and read the change in capacitance from putting your finger near the pad. As an example putting my finger 10mm from a single wire increases the capacitance 0.05pF and my finger 5mm from the wire makes 0.10pF.

    For working with capacitance sensors it really helps to have a high resolution sensitive capacitance meter. Check it out. :)
     
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