As the power and brightness of LEDs continue to increase and prices continue to fall, the use of LEDs in the field of lighting is becoming more and more popular. But in terms of current brightness and price, LEDs have a long way to go to replace white lamps. Now LEDs have the advantage in lighting, because they are color, purity and reliability. Therefore, entertainment venues, commercial displays, and urban landscape lighting will be the main applications of LEDs in the field of lighting.
1, LED commonly used control methods
The control technology of LED lighting fixtures is the key to improving the application level of LED lamps. At present, there are several methods for controlling LED lamps:
Independent control method - use a low price microcontroller or dedicated control chip in each LED fixture. Produce a series of color changes, such as colorful, gradient, etc., and some control chips also have an audio sync port. The LED can be flashed synchronously with the nearby music, there is no control line between the light and the light, and the power is turned on, or the AC zero-crossing synchronization. The characteristics of this product are relatively simple, and the lamp holder and lamp holder are compatible with traditional lamps, and can be mass-produced and exported. However, their shortcomings are that chasing can not be achieved, changing the complex lighting changes of the lights, and not designing the overall lighting scheme according to the needs of the application. Therefore, it can only be applied to local simple occasions.
Inline control method----LED lamps are connected to the controller, and the controller is connected to the network through DMX512 to realize the control of the LED lamps. Another method of in-line control is to include a low-cost microcontroller in each of the lamps, which is controlled by RS485 connection, and also uses a shift register (SPI bus) to transmit LED control signals.
2. Our exploration in LED lighting controllers
When designing the LED lamp controller, we mainly developed the technology of in-line control, and successively developed products such as DALI interface, DMX512, shift register and other solutions. This paper analyzes the advantages and disadvantages of various methods, and proposes a solution that we think is the best, and developed the corresponding lighting control chip. We have been working together for two years.
DMX512 controller solution
The DMX512 is a traditional stage lighting control protocol, a standard proposed by the United States Institute for Theatre Technology, Inc. in August 1986 to transmit 512 thyristor dimming information on a pair of lines.
The DMX512 communication method uses an asynchronous communication format, and each dimming point is composed of 11 bits, one of which is a start bit, 8 bits of dimming data, and two stop bits. Each transmission can have 512 dimming points.
2 / 3 / 4 phase are available.
Matt white / black / silver color for option.
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High PF, high lumen, high CRI, >90Ra, high reflectance diffuser (Lens+Reflector) with 12° / 24°/ 36° for choice.
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