LVDS cables
Some words about LVDS interface to LCD TFT screens .
For those who want to know better - please read this Wikipedia
Almost all modern laptop's (and monitor's) screens are LVDS types, it is type of serial connection to data source .
In short, LVDS is low cable count connection type, made as twisted pairs of data R G B (red, green, blue) plus clock data .
In each LVDS pair exist Positive(+) and Negative(-) wire , and those Positive and Negative must match in LCD socket and controller socket for proper work.
Unfortunate, various screens have various LVDS hardware connectors, like 14, 20, 30, 40 pins and various shapes.
For example 20 pins connectors can look different and use different sockets, but signal pin assignment is the same in both of them.
Also for example, the same looking 20 pin socket in two displays, could have completely different signals at the same pin's numbers, they are scrambled in different way.
The same differences are for all types of connectors, like 14, 20, 30, 40 or other pin sockets.
Signals always should be check with datasheet of particular display.
Many times you can use datasheet of similar display and then check for example positions of GND(using multimeter) to be sure, that order of signals are identical.
Usually, GND pins are "fingerprint" of type of cable we must use. Always check twice or more to be sure.
It is not all, another important for LCD is supply power Voltage, most of screens works at 3.3V but there are some 5V and even 12V.
But it is not all, there is also backlight, it is ambient light behind the TFT screen, that made picture visible for us.
Here we have CCFL lamps, those are driven by piece of electronic named CCFL High Voltage driver, usually controlled by BL(on/off) and ADJ(dimming) control, and powered usually by 12V-20V.
Latest LCD displays are backlit by LED diodes, in that case LCD connector have special input for LED power, usually along with BL(on/off) and ADJ(dimming) control if screen include LED driver, elsewhere there are only raw LED wires and we need to use external LED driver.
LVDS cables are able to deliver signals to various resolution screens, so they are able to deliver serial data 6 bit or 8 bit at 1 channel (odd bits) , some are works as 6bit or 8 bit at 2 channels (odd and even bits).
As last, I must mention that one pair can transmit not only data for one color, but bits of colors can be scrambled depend of LVDS receiver chip, used in particular LCD display.
Well, all above looks not easy and indeed is not.
So before start to work with any LCD display, first of all look for datasheet of your display and read it.
In datasheet are included most important information you will need :
- resolution of screen
- power supply Voltage
- signals to pin assignment
- what LVDS signal is used (ex. 6 bit 2 channels)
Another practical advice, is that
LVDS cables are quite expensive for various screens,
so NEVER THROW AWAY LVDS CABLES from your laptop's screen. If you removed screen from bracket. always KEEP his LVDS cable, the reason is simple, that cable we can reuse for our purposes with our screen. That way we can save time and money for searching and buying cable for particular LCD screen.
Of course, I can imagine many situations that we will buy LVDS cables if we really need, and it is OK.
Is good idea, to keep also all screen's covers and brackets, as it help finally to reuse complete screen's cover with LCD display.
OK, let say we have screen and his LVDS cable used in laptop, as next we must know what type of control board we use with screen.
Especially what socket and LVDS signal pin assignment is used in that particular control board.
Here is good news, it looks like in the cheapest (those are most interesting) universal LCD controller boards, are the same LVDS ports, it is 2mm space standard 2 row goldpin socket, LVDS signal assignment are the same in all controllers, described as 8 bit 2 channels.
LVDS cable assembly manufacturer from China.We could custom LVDS cable following your spec.Welcome to contact us to customized.
Cell Phone: +86-158-8966-1771 Atten: Jacky
E-mail: jacky@micro-coaxial.com
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