Q: What is the brightness, viewing angle and wavelength of the LED?
A: Luminous Intensity is equal to the amount of luminous flux emitted into a very small solid angle at a defined angular orientation from the light source. The measurement for luminous intensity is the candela. Symbol is Iv.
Viewing Angle is the total cone angle in degrees encompassing the central, high luminous intensity portion of the LED beam from the on-axis peak to the off-axis point where the LED intensity is 50% of the on-axis intensity. This off-axis point is known as theta one-half ( 1/2). Two times 1/2 is the LEDs' full viewing angle; however, light is visible beyond the1/2 point.
Wavelength is the distance between two points of corresponding phase and is equal to waveform velocity divided by frequency. It defines what color human eyes could recognize
Q: What is dominant wavelength? Please specify the ranges of wavelength in red, green and blue color respectively.
A: Dominant wavelength is defined as the best range of wavelength showing the most natural color recognized by human eyes. Researches indicate that fixed colors with wavelength of 620-630nm (red), 520-530nm (green) and 460-470nm (blue), in fact mixed in a particular proportion, can get the pure white. That is, in display field, people use luminous materials with above wavelength to make "compounded" white more natural.In order to get a good balance white led display, we specify the led colors with wavelength within 4nm for each color
Q: Which chip vendors are you buying from?
A: It depends on the Customer's requirement. We can purchase from Japan, Korea, Europe, USA. We are using chips mainly from Taiwan
Q: What is the chip size you're using for outdoor display? How about indoor display?
A: For outdoor display, we're using 12mil chip for red, 14mil for both green and blue. Regarding indoor display, 9mil for red, 12mil for green and blue are currently adopted
Q: How much will the brightness of LED drop down after 1000hrs?
A: Based on the result of aging test, the brightness decay of green LED is around 5%-8%, while blue is around 10%-14% and red is around 5%-8%