Wednesday, December 29, 2010
【 Weak current College 】 how to control and improve LED full colour display quality 】
Full color led display to its large size, high brightness, environmental adaptability, irreplaceable advantage, is widely used in advertising media, traffic information, such as indoor sports stadium, the large size of the video display. As the LED chip technology, led packaging technology, led display manufacturing technology of fast lifting and a further decline in prices, full-color led display is through price adjustment critical period. Shenzhen Lehman photoelectric General Manager Li diffuse iron when talking about "how to control and improve the quality of LED full colour display," presented their point of view.
Dedicated LED full color choice
Led device for full-color led display of the most crucial part for three reasons: first, the LED is fully colorful display unit with the highest number of critical devices, each square will use only a few thousand to tens of thousands; second, LED LED is to decide exactly rejecting and optical display performance of the principal, directly affect the evaluation of the audience on screen; once again, LED display overall costs as a percentage of maximum, from 30% ~ 70%.
The selection decision LED the entire screen of more than 50% of the quality. If you fail to select good LED, display of other parts, however good, could not make up for deficiencies in the quality of the display.
Reflect the full color led display dedicated LED an important indicator of quality:
1, failure rate
As a result of full color led display by tens or even hundreds of thousands of groups of red, green and blue LEDs pixel dots, any color LED's failure will affect display the overall visual effect. In General, by industry experience in led display start assembling to aging 72 hours before the shipment failure rate should be no higher than 35 (meaning led device itself causes failure).
LED is a semiconductor device, electrostatic sensitive, easily cause static electricity failure, antistatic life on screen. In General, LED by human failure voltage electrostatic mode test should not be lower than 2000V.
3. attenuation characteristics
Red, green and blue LED have with working hours increasing brightness attenuation characteristics. The pros and cons of LED chip, auxiliary materials is good or bad and packaging technology level determines the rate of decay LED. In General, 1000 hours, 20 Ma test at ambient light, the Red LED of attenuation should be less than 10%, blue, green, LED by the attenuation should be less than 15%-red, green, blue, attenuation of consistency for full color led display future effects of white balance is very big and the display shows the fidelity.
The brightness of the LED brightness is an important decision factor. LED brightness higher, use current margin increases to save power, maintain stable LED. LED has a different point value, the brightness is set in the chip, the smaller the angle, LED the more lights, but the angle of the display is smaller. In general you should select the 100 degree LED to guarantee sufficient angle of the display. In view of the different points-of-sight distance and different display, brightness, angle, and find a balance on the price.
Full color display is made up of countless red, green and blue LEDs pixel tiles, each color LED brightness, wavelength and the consistency of the entire screen determines the brightness consistency, white balance, color consistency. In General, display manufacturers requires device vendors 5nm in the wavelength range and 1: 1.3 brightness range of the LED, these indicators can be used by the device vendor through spectro separations rate achieved. machine Voltage of consistency do not generally require.
Because there is a point of view of the LED, RGB LED display also has angle direction, that is, different point of view, its brightness will increment or decrement. In this way, the red, green, blue three colors LED perspective consistency will seriously affect the different perspectives of the white balance of consistency, directly affect the screen video color fidelity. To do the red, green and blue LED brightness when in different angles of matching consistency, you need to encapsulate the lens design, raw materials select strict scientific design, depending on the package of the technological level of the supplier. Normal direction white balance a good screen, if LED perspective consistency is not good, exactly rejecting and different angle of white balance effect is bad. Led device perspective consistency properties available LED angle Tester measured, for middle and high grade display is particularly important.