Thin Film Transister query

Thread Starter

moomo

Joined Jul 14, 2017
41
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:

RichardO

Joined May 4, 2013
2,271
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.
 

Thread Starter

moomo

Joined Jul 14, 2017
41
How was it able to control each pixel individually without the TFT? Can you remember what type of display it was?
 

RichardO

Joined May 4, 2013
2,271
How was it able to control each pixel individually without the TFT? Can you remember what type of display it was?
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.
 

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