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Energy-saving
LED Display
Background of Design Established from 2002, Lite Pa Co., Ltd. has endeavoured in technology and application of LED display. We also propose the new method for LED driver, signal transmission, and control system. For recent years, the LED components and its packaging tech has improved which boosts up the light efficiency of white-light LED, higher than that of red, green and blue LED. Meanwhile, the issue of environmental protection and energy saving indeed applies pressure to LED video wall. Under this circumstance, Lite Pa proposed a new LED control method, Pre-Synthesize. It applies four color system of YUV color mode instead of the traditional RGB color mode system in LED video wall. Also, we obtain the patent of this new application.
Features Energy-Saving
Sharpness
Compatibility of Black/white and color images
Lite Pa Energy-saving RGBW LED Display
Energy-saving 33.2%(Ave.)~66.6%(Max.)
Prolong lifetime of display
Lower down the strict requirement for RGB lightness proportioning
The average lighting time of the LED lamps in RGBW display is half than the time of LED lamps in RGB display.
Traditional vs New LED Display Intro of Theory
Traditional display: based on RGB color mode Yellow = Red + Green Purple = Red + Blue Indigo = Green + Blue White = Red + Green + Blue
RGB as one pixel in traditional LED PCB.
New display method based on YUV color mode:
RGBW as one pixel in new LED PCB.
Y R-Y G-Y B-Y
Brightness measure aberration measure aberration measure aberration measure
Math deduction analysis & Application to product Math deduction analysis Based on the previous equation, if a, b, c doesn’t equal to zero, then three basic colors can mix. Remove the least among a, b, c and add white. The white can mix with the other two colors.
They could be like the below: (1) a=b=c color_out＝a*W (2) a=b <c color_out＝a*W+|c-a|*B (3) a=c < b color_out＝a*W+|b-a|*G (4) b=c < a color_out＝b*W+|a-b|*R (5) a<b<c (They don’t equal to each other.) color_out＝a*W+(b-a)*G+(c-a)*B (6) b<a<c (They don’t equal to each other.) color_out＝b*W+(a-b)*R+(c-b)*B (7) c<a<b (They don’t equal to each other.) color_out＝c*W+(a-c)*R+(b-c)*G The rest can be deducted by analogy.
Application to product
Energy-Saving Mode Color saturation not affected. Requirement R-30 / G-40 / B-50，the actual display status would be R-0 / G-10 / B-20 / W-30 color-out = dW+(a-d)R+(b-d)G+(c-d)B This is under Energy-Saving mode
Brightness Mode Sacrificing color brightness lifted. Requirement R-30 / G-40 / B-50， brightness lifted 20，the actual display status would be R-30/ G-40/ B-50 / W-20 Brightness lifted: color out = aR+bG+cB+(manually increase 0~100%)W
Compare the current (1) As LED characteristics, the light-emitting efficiency of White LED is higher than RGB LEDs. We can just place White LED directly to subsitute the white light of mixturing RGB LEDs. Due to the same current consumption at each LED, when raising the light-emitting efficiency of white light, RGBW will save more energy than RGB.
The common light efficiency as below: Driving current＝20mA Beam angle＝100*50
LED
RED
GREEN
BLUE
WHITE
Brightness (mcd)
620
1200
280
2200
Based on the previous: (1) a=220 b=220 c=220 color out＝220*W (black & white)
current
Traditional 52mA
(2) a=128 b=128 c=200 color out＝128*W+72*B (single-color saturation)
current
Traditional 36mA EnergyNew 21mA saving
current
Traditional 25mA
(3) a=32 b=80 c=200 color out＝32*W+48*G+168*B (Any two of the three basic colors mixture) (4) In other situation, any one or two of a, b, c is zero without white-light LED lit up, the power consumption is the same.
New
New
current
The Same
17mA
19mA
Energysaving
66.6%
56.1％
Energysaving
24 ％
Energysaving
0％
Compare the current (2) Statistics for image color: Three color mixture TV shows/ movie Test on spot
Item
Spec
Two color mixture
68% Energy-saving
Single color mixture
28%
4%
35%~42%
P16 full color/ static driving/ resolution8 00*600/（calculated in RMB） RGB system
RGBW system
Energy-saving
Consumption
86KW
53KW
38%
Daily consumption (8hrs/day）
688/550 dollars
424/339 dollars
211 dollars
Annual consumption
251120/0.2 million dollars
154760/0.12 million dollars
80 thousand dollars
Lifespan (8 years/ unit)
2008960/1.6 million
1238080/0.96 million dollars
640 thousand dollars
Compare the image Sharpness When the image is synthesized in brightness and aberration, human eyes have good identification to black and white, and thus the sharpness can be boosted and itâ&#x20AC;&#x2122;s more obvious with closer look.
RGB system
RGBW system
Lift up the lifespan of the display The experiment of the complete image synthesized by brightness and aberration measure testifies that human eyes have lower identification to the details of full color image than those of black and white. ● In RGB system, any of the three colors decays, the aberration of brightness will be noticed by human eyes easily. ● In RGBW, any of the four colors decays, the brightness measure isn’t affected. ● The average lighting time of the LED lamps in RGBW display is half than the time of LED lamps in RGB display. The above features can prolong the lifespan of display. The original image
RGB system
RGBW system
Compatibility Compatibility of black & white & full color
Compatibility of the PCB Driver IC：8 bits or 16 bits w/ constant current, MBI5026 / ST2221 Driving：Same decoding, static or 1/2,1/4,1/8,1/16 driving LED allocation：Rectangle/ vertical/ horizontal
The original image
RGB system
RGBW system
To separate brightness signal into RGB measure, not compatible to the original system.
No need to change the system which is compatible to the original system.
RGB system
RGBW system
Compare the cost Sample specification: Pitch：P16 Resolution：32*32 Driving：Static driver
Item
System
RGB system
RGBW system
LED
2048R/1024G/1024B
1024R/1024G/1024B/1024W
Driver IC (mbi5026)
192/256*
256
PCB size
Same
Same
Power
307W
200W
Total cost
*****
5~7% increased
● In visual display mode, 256 driver IC are applied but in actual display mode, 192 driver IC are applied.
Compare the light effect of image Left: RGB/ Right: RGBW
Red 255
Blue 255
Green 255
White 255 (6500K)