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I was trying to hack a 3-D system starting from the monitor: VG248QE. I teared it down to LCD matrix and driver. This is a 1080p(1920 x 1080) monitor so I was expecting that at least 1080(row) + 1920(columnn) = 2000 pins wired from the LCD driver to the LCD Matrix(I am not counting RGB's also!). However, I see 6 x 90 = 540 pins going to the LCD Matrix and I did not see any component(deMUX, MUX etc) on LCD matrix.

LCD driver to LCD matrix

I looked up for the Driver chip online but found nothing(no datasheet!).

LCD Driver chip

The question is, how does the driver drives so many pixels with so less pins? Am I not seeing MUX's embedded in LCD matrix? Or is there something else I am missing?

And just to share: VG248QE uses LCD overdrive method to achieve 1ms LCD rise/fall time and uses this chip for several levels of supply(+/-40V, 30V, 15V ...) for overdriving:

OVERdrive supply chip

Alper91
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2 Answers2

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A LED/LCD display is constructed of multiple panels: 16x16, 64x64, etc depends on the supplier.

enter image description here

These panels are mounted such to produce the 1920 x 1080 pixels

Each panel will have its own interface IC and LED/LCD driver chipset like the tlc59283

How is each panel/module controlled? via a serial interface.

If you look at a 320x240 panel such as this one you will see its interface is only 40pins wide & it clocks through D1:DH1 --> D320:DH240 as it reads in the RED, GREEN, BLUE data line to determine the hue saturation and brightness to be applied to the cell to be illuminated.

Larger displays use more panels and with vertical scan rates of say... 100Hz but with a fixed serial bandwidth per panel... a larger number of data lines are required to address each panel in a parallel fashion.

http://www.edn.com/design/led/4432914/How-to-design-LED-signage-and-LED-matrix-displays--Part-1

http://www.fujitsu.com/downloads/MICRO/fma/pdf/LCD_Backgrounder.pdf

  • Thank you both for such detailed answers. Now I understand the method. Now, you both responded with correct and fully understandable answers so I feel like I have to reward the first one as the answer. – Alper91 Dec 28 '15 at 09:39
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Typically there are long skinny driver chips for row and column. They may be on the outside COF (Chip-On-Flex) or inside COG (Chip-On-Glass construction) the panel itself. Here's an HD TV panel from Dave Jones' blog showing the COF column drivers:

enter image description here

Here you can find a datasheet for a Novatek driver chip showing the data interface for 384 outputs- 128 x 3 for RGB- they feed 6 bytes in parallel into the chip (48 pins) to give 384 outputs.

In the case of an HD panel you would have 1,080 row drivers and 5,760 column drivers (1920 x 3). The video shows 8 column driver chips, each with 720 driver 'pins'.

enter image description here

Generally you will not find much information available online on this kind of part as they are only used by a very few customers.

Spehro Pefhany
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  • Thank you both for such detailed answers. Now I understand the method. Now, you both responded with correct and fully understandable answers so I feel like I have to reward the first one as the answer. – Alper91 Dec 28 '15 at 09:39