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New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

T400/410/420 and T500/510/520 series specific matters only
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TPFanatic
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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#61 Post by TPFanatic » Thu Nov 01, 2018 6:56 pm

The screens that are compatible are so because they are specifically programmed to be compatible with the adapter board, which identifies itself as the LCD to the laptop. So I don't think that screen would work.
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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#62 Post by dr_st » Fri Nov 02, 2018 1:09 am

TPFanatic wrote:
Thu Nov 01, 2018 6:56 pm
The screens that are compatible are so because they are specifically programmed to be compatible with the adapter board, which identifies itself as the LCD to the laptop.
So, these screens were used with similar adapters in some commercial laptops as well? Or else why would anyone bother programming them such way?
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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#63 Post by Pokrzept » Fri Nov 02, 2018 4:03 am

TPFanatic wrote:
Thu Nov 01, 2018 6:56 pm
The screens that are compatible are so because they are specifically programmed to be compatible with the adapter board, which identifies itself as the LCD to the laptop. So I don't think that screen would work.
What do you mean by that? The EDID file in the displays EEPROM has been modified so the adapter board can "communicate" with it properly? If so there's a big chance that B140HAN01.8 will work properly after small EDID update.
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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#64 Post by tdot » Fri Nov 02, 2018 5:59 am

TPFanatic wrote:
Thu Nov 01, 2018 6:56 pm
The screens that are compatible are so because they are specifically programmed to be compatible with the adapter board, which identifies itself as the LCD to the laptop. So I don't think that screen would work.
I've heard that but that's actually what I don't understand ... and like dr_st I don't quite understand why. (i.e. RMSMajestic asking why don't they support other panels)

Most likely I think I'm missing some understanding of how the eDP protocol works. Is eDP not just a standard interface? Why would the adapter board care what kind of screen it has plugged into it? If the eDP interface is standard, what difference would it make to the converter board? Unless they artificially limited the supported panels, which to me wouldn't make any sense. I'm pretty sure LVDS just sent a video signal not caring what receives it - does eDP require two way communication to output a signal?

If it 'should work' but is 'not supported' I'd consider trying it at least. I'm curious to see a glossy screen, and from what I've read I think the 1.8 is a superior panel (I believe it has a slightly higher contrast ratio and slightly less power consumption) to 1.3 (which spec wise I believe is thinner to 1.2). But if the adapters are locked to certain screens I'll just forget it.

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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#65 Post by TPFanatic » Fri Nov 02, 2018 3:43 pm

tdot wrote:
Fri Nov 02, 2018 5:59 am
I've heard that but that's actually what I don't understand ... and like dr_st I don't quite understand why. (i.e. RMSMajestic asking why don't they support other panels)
Ok I spoke backward. I did not mean the LCDs are programmed to work with the adapter board. I mean the adapter board is programmed to work with those specific LCDs. The adapter board has its own firmware that allows it to talk back to certain screens. Javi-Jie put in firmware for each supported screen, and firmware does not exist for other screens, so other screens simply will not work.

The T420, T420s, T430, and T430s do not know how to talk to eDP. eDP and LVDS are different languages. Rather than just making an LVDS to eDP adapter cable, the adapter board is necessary to tell the laptop the specs of the screen. It is the adapter board that tells the laptop "I am a screen." In fact it tells the laptop "I am a B140HAN01.3 with these specs ... " regardless of the fact that my screen is actually a B140HAN01.1, not a 1.3, it tells my computer it is a 1.3. Because it is the adapter board identifying to the laptop that it is a screen, not the screen.

RMSMajesty asks why they don't support other panels, to indicate that the adapter board is a clone of Javi-Jie's prototype, which only supports those specific panels. If the Chinese adapter boards were truly original they would support more panels or be an entirely different design.

You can of course try it but do not be surprised if it does not work. I will be surprised if it does.
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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#66 Post by tdot » Fri Nov 02, 2018 4:04 pm

TPFanatic wrote:
Fri Nov 02, 2018 3:43 pm
tdot wrote:
Fri Nov 02, 2018 5:59 am
I've heard that but that's actually what I don't understand ... and like dr_st I don't quite understand why. (i.e. RMSMajestic asking why don't they support other panels)
The T420, T420s, T430, and T430s do not know how to talk to eDP. eDP and LVDS are different languages. Rather than just making an LVDS to eDP adapter cable, the adapter board is necessary to tell the laptop the specs of the screen. It is the adapter board that tells the laptop "I am a screen." In fact it tells the laptop "I am a B140HAN01.3 with these specs ... " regardless of the fact that my screen is actually a B140HAN01.1, not a 1.3, it tells my computer it is a 1.3. Because it is the adapter board identifying to the laptop that it is a screen, not the screen.
I guess I need to look deeper into the eDP protocol. I understand the above, I just don't understand why it the adapter board cares (or has to care) the difference between a B140HAN or an "anything" that takes eDP as input. I would have assumed the actual display signal signaling between any eDP interface and panel are the same - as I'm pretty sure is the case in LVDS (which IICR is just sync+bit streams per color).

In other words, I understand that the boards are probably programmed to communicate with a specific EDID, but not why it can't just output a 'valid eDP signal' regardless of what its plugged into ... I mean, 99% chance the signalling for B140HAN01.3 and B140HAN01.8 are identical - so the question is, the converter board/eDP can't just 'output a signal for B140HANxxx ignoring the EDID'?

I know it's not really relevant to if it will work or not, just curious :lol:

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Re: New IPS FHD Upgrade Kit for thinkpad T420 T430 ,And T430S T420S

#67 Post by RMSMajestic » Tue Nov 06, 2018 8:32 pm

tdot wrote:
Fri Nov 02, 2018 4:04 pm

I guess I need to look deeper into the eDP protocol. I understand the above, I just don't understand why it the adapter board cares (or has to care) the difference between a B140HAN or an "anything" that takes eDP as input. I would have assumed the actual display signal signaling between any eDP interface and panel are the same - as I'm pretty sure is the case in LVDS (which IICR is just sync+bit streams per color).

In other words, I understand that the boards are probably programmed to communicate with a specific EDID, but not why it can't just output a 'valid eDP signal' regardless of what its plugged into ... I mean, 99% chance the signalling for B140HAN01.3 and B140HAN01.8 are identical - so the question is, the converter board/eDP can't just 'output a signal for B140HANxxx ignoring the EDID'?

I know it's not really relevant to if it will work or not, just curious :lol:
The eDP protocol is for transferring data. However EDID is what is used to drive the panel. Just like for harddrive, IDE/SATA/M.2 are just protocols for data transfer but for the HDD to work you will need specific firmware stating the cache size/RPM/reallocation/possible SLC cache etc. Like you can't drive a 4200 rpm HDD to 10k rpm
https://en.wikipedia.org/wiki/Extended_ ... ation_Data

The more ideal kit would be to read the EDID firmware and drive it accordingly. But that is not the ideal solution for the purpose of this converter kit, as it adds more to the cost, space and power consumption or perhaps is beyond what Javi was capable of. So the EDID is embedded in the firmware to make things simple.


Back to B140HAN01.3 & .8, I think they are all based on the same technology, but can't promise anything about that.
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