Thin Film Transister query

Discussion in 'General Electronics Chat' started by moomo, Sep 16, 2018 at 1:16 PM.

  1. moomo

    Thread Starter Member

    Jul 14, 2017
    40
    0
    Hey,

    Can you buy the Thin Film Transistors on a substrate such as glass (like those used in flat panel displays) as a complete off the shelf product - without having to buy a complete display? Or would these have to be manufactured for specific applications?

    Many thanks
     
    Last edited: Sep 16, 2018 at 1:47 PM
  2. RichardO

    Senior Member

    May 4, 2013
    2,268
    877
    Here is my understanding:
    The reason for thin film transistors is to make the display without having a separate driver PCB and the huge number of wires between the display glass and the PCB. I think this is accomplished by having multiplexers or shift registers on the display with the thin film transistors.

    One display I looked at used an IC with *thousands* of pads to drive the display directly -- not separate thin film transistors or shift registers/multiplexers. I assume it was mounted to the display glass using bumps (like in a BGA package) rather than wire bonding.
     
  3. moomo

    Thread Starter Member

    Jul 14, 2017
    40
    0
    How was it able to control each pixel individually without the TFT? Can you remember what type of display it was?
     
  4. RichardO

    Senior Member

    May 4, 2013
    2,268
    877
    The transistors and control electronics are all in one IC having a massive number of pads or bumps.

    While writing that I was trying to remember the part number for the driver IC I mentioned. Still coming up blank, though.

    I did find this link. I has a description of chip on glass:
    https://www.newhavendisplay.com/pkc_lcd_cog.html

    The link shows that TFT is not obsolete like I thought. I had assumed, wrongly, that chip on glass had replaced TFT.


    I have attached a data sheet for a chip on glass driver for a small monochrome graphic display having up to 255 by 160 pixels. Note that it has over 500 connections.
     
  5. moomo

    Thread Starter Member

    Jul 14, 2017
    40
    0
    Many thanks, that is really helpful. Kind Regards
     
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