How TFT panels attached to PCB - Page 1
Forum section: electronics / general

author: Bud
author_rank: Super Contributor
timestamp: September 04, 2014, 02:40:40 am
content: I have a few TFT modules of different size but they are modules with TFT panels already mounted on the carrier PCB. I can't figure out for sure what holds graphics panels in place, how they are attached to the PCB. Is that by means of sticky strips on the back of the TFT panel ?

author: Rasz
author_rank: Super Contributor
timestamp: September 04, 2014, 03:44:11 am
content: my Crystal Ball is scratched and I cant see your lcd panels clearlyhow about some pictures?

author: David_AVD
author_rank: Super Contributor
timestamp: September 04, 2014, 05:12:35 am
content: I was wondering the same thing only this morning when looking at some 7" touch panels I have. My guess is thin adhesive tape.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 04, 2014, 05:13:19 am
content: Usually double-stick tape and registration pegs; electrical connection via FFC/FPC connector.Good tip for dealing with the short life cycle of LCD modules: build a cheap carrier board with a standard connector (FFC, ribbon cable, board-to-board headers..), add a few bits for compatibility (backlight driver, logic converters or decoders, or even a controller), and rev a new one every time you have to buy a new supply.Tim

author: Bud
author_rank: Super Contributor
timestamp: September 04, 2014, 05:24:14 am
content: Rasz - there is not much to look at, it is just a PCB with a thin LCD panel laying flat on it. You can search on eBay for "tft module", plenty of photos there.

author: Bud
author_rank: Super Contributor
timestamp: September 04, 2014, 05:28:50 am
content: Quote from: T3sl4co1l on September 04, 2014, 05:13:19 amThanks but no thanks, life is too short to brew your own graphics controllers, I instead buy modules with graphic controllers built-in.

author: David_AVD
author_rank: Super Contributor
timestamp: September 04, 2014, 06:59:29 am
content: Quote from: T3sl4co1l on September 04, 2014, 05:13:19 amThat's the exact reason I was looking more closely at the 7" ones I have here. The only hard to solder bit is the fine pitch SSD1963 chip.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 04, 2014, 07:32:34 am
content: Quote from: Bud on September 04, 2014, 05:28:50 amI've seen some that include GUI widgets -- all you need is an insert-protocol-here and your API is ready to go, high level, event driven.Great for development, but hope you didn't need your dollarsigns!Quote from: David_AVD on September 04, 2014, 06:59:29 am...Which really just comes down to,How much is it worth it to you?Plain LCDs are cheap, but require a lot of hardware. A controller chip alone might cost you the $5 you hoped to save over a COG type.The kind with onboard controllers (or a frame buffer at least) are easy enough to use, but you'll spend a long time either writing your own graphics routines, or debugging someone else's. (Isn't it great that open software can be improved by anyone?...and often, needs to be, several times over, before it's generally useful?!)Or you can get some damn fine modules with medium level (accelerated graphics?) or high level (GUI events?) drivers built in, which will save you a lot of development work, but how much can you really afford, especially if it goes to production?Overall, it's hard to say if any one solution would be the most useful among the alternatives, even for a given application -- on the plus side, the difference is probably only a few bucks, but if you are tasked with optimizing every thin cent out of a product, you'll have no choice but to do some serious homework to evaluate them all.Tim

author: David_AVD
author_rank: Super Contributor
timestamp: September 04, 2014, 09:12:20 am
content: For me, it's about a TFT + touch + controller solution that we'll have a little more control over (quality and repeatability). Cost is of some concern, but if we can build a better unit for $80 than the current $50 one from China I'd be happy with that.The LCDs themselves seem reasonably common, but having only one or two sources for the completed unit with PCB worries me too. I'd also remove the features we don't need (SD card slot and flash memory) and replace the 2 female headers with 1 male one so we can use easier-to-make female-female IDC cables.