NEC 8.4" Transflective Solution - Custom Kit

**turbocad6** · 09-12-2007, 12:20 PM

it's surprising how much light is really needed, those led strips are made to be direct replacements for the ccfl, while they may be an improvement over the ccfl, I wouldn't expect it to be a drastic improvement really.

my screen backlight is estimated at somewhere in the 30,000 nit range before the screen, that's 32 1 watt luxeon leds that can be driven to around 1,000 nits each.... I estimate after the lcd I'm consevatively in the 1,400-1,500 nit range... making this much light will normally bring extreme heat....

that's the beauty of transflective & reflective, they harness the ambient light & utilize it... a transflective screen can be rated at like 170 nits & still be viewable in the sun... the reflective screen I'm using in my new install can be at 0 nit brightness, no light at all, inverter unplugged, & it still looks insane in the sun. that being said, my super bright lcd definatley looks better than the transflectives & reflective all around, but after going thru everything I did, I think trans or reflective is *choke*, good enough I guess

**thermoptic** · 09-12-2007, 01:42 PM

I am starting to think that the Effective Contrast Ratio (ECR) specified in the Rugged PC Review article is too narrow in scope. Based on the capabilities in either optical films or inherent within the LCD TFT itself, a reflective or transflective display would have a variable, say TRANS_INC_NIT, that would be proportional to the sunlight intensity and would help improve the final ECR value. The current ECR equation uses 10,000 nits for average sunlight.

Perhaps we could use the following modified equation:

ECR = 1 + ( (AMB_NORMAL_NIT + TRANS_INC_NIT) / ( 10,000 NITS * SURFACE_REFLECTIVITY_PERCENTAGE) )

Winmate discusses estimated NIT requirements based upon viewing environments here:
http://www.winmate.com.tw/Sunlight_Readable.htm

The following links, which I have no time to read on my lunch break, provide a deeper discussion of transflective LCD operation and testing, but no visible modified ECR equations:

http://lcd.creol.ucf.edu/publication...ID06_p_157.pdf
http://www.hec.afrl.af.mil/Publicati..._2428Meyer.pdf
http://www.freepatentsonline.com/20050006652.html
http://www.qualcomm.com/technology/i...hite_Paper.pdf

I may contact the author of the Rugged PC Review article and get his take on the impact of transflective operation on the ECR equation.

Skipping lunch to research car PC displays...man, I may need to join a support group.

**thermoptic** · 09-12-2007, 02:20 PM

Originally Posted by DarquePervert

Hey thermoptic....
It says that there is no inverter supplied. What is the inverter used for? Backlight? Something else?
Where could an inverter be obtained that would be appropriate for this LCD, assuming one is actually needed?

You will also need a VGA-to-LVDS interface, if this exists? If you have an EPIA board with LVDS connector, you will need a controller interface card for RGB control. I haven't looked into this yet. It is next on the list. Turbocad6 estimates $100+ for a good LVDS controller but I don't know what this covers.

**turbocad6** · 09-12-2007, 02:35 PM

if your board has lvds out you don't need anything but a cable to connect the 2, no interface board is necissary at all. of course you'll still need an inverter. many who can supply the vga-lvds board can also provide the package, which would include the board, all cables & inverter for said screen... a package like that could be over $250 last I checked..

yeah, tons of research is necissary, a little knowledge is a dangerous thing, just having some of the facts leads to incorrect conclusions most times..

as far as transflective goes, it definaley reduces the overall actual nit brightness of the screen, but then taking the boost into account from ambient light, the overal nit 's are higher overall. transflectives are generally less contrast than a standard panel.

on a note about contrast & brightness, I did my bright screen twice actually, the first panel I used was a more standard laptop panel, when the light was fully cranked it was severly washed out, sunlight viewable & an improvement over stock big time, but still washed out. this, along with horrible viewing angles, I just wasn't satisfied with the end results, I winded up redoing it with the boe hydis panel...

now the boe hydis panel uses a different technology as you've seen, it is almost like a transflective in most ways to begin with, & when you super bright a transflective screen it doesn't wind up being as "actual" bright as a non transflective, so the end result of the hydis was not as bright as the standard panel really, still super bright, but not as bright.

the hydis screen however, even with 30k nits behind it, has awsome contrast.... it looks soooo much better than my first lcd, even though technically it's not as bright...

there are so many variables in the stack of an lcd that it is hard to know how a panel will react to so much extra light, many will wash out & loose contrast big time, when a factory builds a sunlight viewable high nit screen they take this into account, & match the optical stack to the job at hand, but home brew does not have that luxury... even transflective upgrades need modifications to the rest of the optical stack for contrast & viewing angle tweeking...

I feel you pain, when I did mine I did so much research it wasn't even funny, many many hours really of reading & learning... a few years later I remember some of what I learned, but there is just so much to the overall equation...

**thermoptic** · 09-12-2007, 04:23 PM

Of course there are VGA-to-LVDS controllers!

They are used in all displays! Lack of sleep is taking its toll…

Turbocad6, I’m glad you’re here to guide noobs, such as myself, through this complex transflective web. Bad decisions from too little information can be dangerous indeed.

It appears that the EPIA EN15000G only needs the transmitter card to connect to the panel:

VIA LVDS-07G 24-Bit
http://www.mini-box.com/VIA-LVDS-07G...=8&category=20

VIA LVDS-07G 24-Bit User’s Manual
http://resources.mini-box.com/online...-24-manual.pdf

Via VT1631L LVDS Transmitter Chip
http://www.via.com.tw/en/products/vi...y/lvds/vt1631/

It appears the VIA LVDS-07G card ALSO routes panel controller voltage (3V) and inverter voltage (5V) but I need to check the specs on the EPIA EN15000G. I don’t know if it can supply enough current. Hopefully the NEC panel spec can answer these questions. I will still need the inverter to drive the CCFL.

**thermoptic** · 09-13-2007, 04:20 AM

I received my tracking number for the panel and I should have it on Friday. I ordered the LVDS-07G from Mini-Box and the inverter from Future Electronics. These parts will arrive early next week.

84PW041 Inverter Spec:
http://www.stobby.co.uk/RDS/nec-dl.asp?f=84PW041.pdf

The NEC LCD specification lists the connector types for the panel. The last item to complete the display integration is the LVDS cable. Giuliano identified the connector types on the LVDS-07G in this post: http://www.mp3car.com/vbulletin/981023-post36.html. Nice work.

I guess I need to decide where I’m going to put my car PC in order to size the interface cable. This cable assembly will contain the LVDS signals, 3V panel supply, 5V inverter supply, and probably the touchscreen signals. I see that MCT can assemble long, custom LVDS cable assemblies. See review here: http://www.mp3car.com/vbulletin/1052877-post1.html

It feels good to finally have the display components selected and ordered. Hopefully, I can resume a normal sleep schedule.

You don't want to know how much sleep I am averaging a night.

Next I need to select the touchscreen. I will continue to track that effort in the Input Devices forum.

**spmclaugh** · 09-13-2007, 02:14 PM

Looks like you found the NEC panels that I was going to recommend - the standard one and the LED backlit one. From my other post, you can also check out the Toshiba LTD089EXWS, Optrex T-51638D084J-FW-A-AB, and Sharp LQ088H9DZ01. None of my "favorite" distributors stock the Toshibas or Sharps, but I've sent out requests for single-volume pricing to some other distributors. Except my requests were for 6.0 - 6.5" models.

BTW, CAT5 cable is actually recommended for LVDS (even CAT3 is acceptable), you'd just need to find the end connectors (or hard-wire it).

**spmclaugh** · 09-13-2007, 03:01 PM

Also, even though the NEC's have the best resolution (by far), their technology seems to differ from traditional transflective in some way. Their "natural light technology" might be similar in spirit, but you think that they'd advertise it as such if it was standard transflective. The google search I used to find them was "NEC transflective", and I found some industrial/electronics magazine article on "thomasnet" called "Transflective LCD Modules target industrial displays". But I think that they are mistaken - the NEC data sheet does not mention transflective anywhere. I found another article on NEC's web site that seems to suggest it actually switches "modes" from fully reflective to fully transmissive, depending on a switch that can be flipped. That could be annoying if you're driving under bridges, around trees, etc.

**spmclaugh** · 09-13-2007, 03:20 PM

If I'm post-whoring already, might as well continue... The link was: http://www.nec-lcd.com/en/technology/nlt_sr_nlt.html

Though I've since read a few more articles that directly quoted NEC spokespeople as saying their ST-NLT technology is synonymous with transflective.

BTW, you won't need an inverter on the model you're currently looking at -- it's LED based.

**turbocad6** · 09-13-2007, 03:28 PM

the hydis is similar, in that it's similar to transflective, but not really stated as transflective...

I thought the best resolution was a panel that I have, it's a toshiba ltm06c310, mine was upgraded by nathan fpd, it's a 6.3 with 1024x768

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