Q: why must be constant current led power driver source?
A: first of all is the LED diode, its characteristic curve and the common diode are basically the same, when the applied voltage after reaching diode turn-on voltage, and voltage change can cause the diode current shift. NiuBao power points out that the led power driver using constant current is to ensure that led the constant current, no matter how change voltage, constant current through the led, ensure the service life of the led and light failure. Say again LED, affecting the service life of the LED is the key to the temperature, when the LED at higher temperatures, the junction resistance decreases, that is, current reduce small, under the same voltage, temperature increase will lead to the LED current, current increase and make temperature rise further, this vicious circle will be burned LED, LED light failure as well as related to temperature, temperature rise time failure, presents the phenomenon which is bright not bright. Investigate its reason, LED the rise of temperature, caused by 2 reasons, one is the quality problem, its heat conduction ability is poor, when LED encapsulation of LED tube core temperature less than surface cool (internal), even if we add the internal heat radiator also can't take out, and some against the products without the cooling device. 2 it is the power caused by temperature rise, which is caused by the current temperature, when the LED conduction, because of its nonlinear, the change of the weak power supply will cause a sharp change LED current, leading to a rise in temperature. Using constant current source is in order to overcome the above problems.
Q: the export of LED lighting lamps and lanterns must use isolated power supply?
A: look what export to countries, safety certification is different in different countries, as exports to the European Union, have CE, and CE no isolation power supply also can pass, but you are exported to the United States and Canada, will UL certification of UL power supply, this is to isolate the power supply. So you still national reference related information according to your target. Realistic, though, finally you still get isolated power supply, safer, so don't have to worry about after-sales.
Q: LCD driver power supply must meet? How to adjust the LCD contrast?
Answer: 1, LCD driver power supply must be good, otherwise the backlight bulb does not light, LCD panel also won't show the image. 2, LCD contrast adjustment by the control circuit and LCD driver board.
Q: what is the principle of no drive LED?
A: it is now some leds do encapsulation will drive and lamp bead encapsulation together on a small plate, and then as a whole sale, the seller is called no drive leds, actually still have driven, just go do it, you don't have to buy separately.