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Second - everything which is described below I've made on my own risk and if anyone tryes to duplicate any part of the text, has to keep in mind that with his actions one can destroy both LCD and/or a laptop motherboard, So I WILL NOT BE RESPONSIBLE FOR ANY DAMAGES CAUSED FROM THAT !
As you know one of the problems of the X61 tabled is a low brightness of it's CCFL backlight. According to that , before nearly half a year I had an idea to implement an LED backlight but due to lack of free time I succeed to realize it this week.
What were the main goals in this project :
1. to make a LED backlight which brightness will be not less than the CCFL one.
2. the power consumption of the driver + LEDs should not be more than that of the inverter+CCFL
2. to make a driver for those LEDs to drive them with their nominal current, and with constant and equal brightness for all leds.
3. to ensure those driver to be controlled like a standard CCFL inverter - with Fn+Home @ Fn+End buttons
4. to make the LED driver with the same dimensions like the inverter and the LED strip with same dimensions like a CCFL
First after a brief lookout over a original inverter I found a MP1010B IC which datasheet helped me to understand how it is controlled. So the main supply voltage is 19.8v , enable voltage is 3v and the brightness is controlled by 1.8v PWM signal. Also it was easy to find which pin of the connector is for what.
After a little search over Internet ,the best LED driver IC for conditions above was found - TPS61181 . It is for 60 leds and the leds which I've used are those - 0603 SMT 2300mcd WLED
Other thing that we will need is a donor inverter for a power connector and part with directional buttons for tablet mode (the circle next to the fingerprint sensor). I buy it from there - inverter .
Here are some pictures of the work process:
from top to bottom : a green ruler
; PCB for 60 leds 2mm X 250mm; a part of the LEDs in 0603 body (small yellow dots on the black strip)----------------------------------------------------------
LED driver PCB which I've made by a foto-resist method and the small black square is the TPS61181
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on top is drivers PCB with electronic components already soldered and below it are soldered LEDs on their PCB; on the bottom is a donor CCFL inverter
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Closer look of a driver PCB
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LED strip is connected to the LEDs driver board.......
... AND IT'S WORKING
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With the red arrow I've shown the part with the buttons which had to be glued to the LED driver board
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LED strip vs CCFL and at the top corner you can see glued part from the donor inverter
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Here you are some pict from the assemble of the new backlight
And a few pict on LCD disassemble ( I was a little bit nervous here
)
And because this mod is nothing without comparison between both backlights , here it is :
I don't have luxometer so I've used my camera for before and after picture comparison
Up is with CCFL and below is with LEDs. I've took a picture in dark room with same camera exposure w/o a flashlight ,so as it seems the LEDs are a little brighter. YEEESSSS for now - and we can go to the next comparison....
Power consumption test:
I've measured both voltage and current on inverter and LED driver in working condition ,first on min brightness and than on max brightness.
Here are the data:
for CCFL inverter,min - supply voltage: 19,9v x 0,02amp = 0,398W
for LED driver, min - supply voltage: 19,9v x 0,02amp = 0,398W
as it seems the power consumption at min is the same, lets see on max...
for CCFL inverter,max - supply voltage: 19,8v x 0,21amp = 4,158W
for LED driver, max - supply voltage: 19,8v x 0,19amp = 3,762W
That's are nice results ,with less consumption on max we've got a little more brightness than a CCFL.
In conclusion I may say that all the 4 goals are more or less completed.
If you ask me does it worth all that work, investment,time , and risks took for a little more brightness, my answer is BIG NOO except if you enjoyed working with electronics like me and /or this is your hobby. I really enjoyed this project and the positive results from it.
)
