RGB LED is a LED that can create different colors with red, green, and blue lights. Under the coat of an RGB LED, there are three small LEDs, which respectively emit red, green, and blue light. It has 4 pins, three of them connecting these red, green, and blue lights, and the other one attaches to a common anode (+) or cathode (-). Start reading and know more about it.
Principles of RGB LED lights
Additive and subtractive color models
RGB is the abbreviation of Red, Green, and Blue. They are the primary colors of an additive color model. What is the additive color model? It means to create colors by adding different degrees of red, green, and blue colors. You can get a white color once setting values of red, green, and blue color to the maximum. On the contrary, there is another color model which is called the subtractive color model. Basically, it consists of three colors: cyan, magenta, and yellow. A combination of these colors will be black. This model is used in the printing industry since it is a process of absorbing and reflecting lights. Unlike the subtractive color model, the colors the additive color model produces are brighter. And our eyes are sensitive to red, green, and blue lights. So the additive color model is what we use for RGB LED lights.
How to apply this principle to make lights of different colors? Red, green, and blue colors have values ranging from 0 to 255. To get a certain color, you will need to adjust the corresponding values of red, green, and blue colors. For example, to get yellow, the values will be Red=255, Green=255, and Blue=0. Usually, this setting will be achieved by programming codes in devices like computers.
Since the range from 0 to 255 is quite wide, it enables you to create more than 16 million different colors. This impressive feature makes RGB LED preferred in many fields such as indoor and outdoor decoration. Besides, RGB LED is not like white LED, which creates white light by using phosphors to transform other lights. It gets white light by adding lights. In this way, it will not cause much energy loss. Instead, the white light it creates will be brighter.
Common Anode and Common Cathode RGB LEDs
For the longest pin of RGB LED, there are two types. One connects a common anode and the other connects a common cathode. But they don’t vary much from each other. You just need to wire and connect the circuit in different ways.
For an anode RGB LED, the red, green, and blue leads will be linked to lower voltage or GND. And anode lead connects the positive terminal of the power supply.
For a cathode RGB LED, on the contrary, you need to connect red, green, and blue leads to a higher voltage. And cathode lead links the negative terminal of the power supply.
Multimeters can help to distinguish between these two. First, find the longest pin which is designed for a common anode or cathode. Second, place the red tip of the multimeter which stands for the anode on this pin and the black tip on one of the other pins. If the LED lights up, then it is an anode RGB LED. In the same way, place the black tip on the longest pin and the red one on another pin. If it is a cathode one, there will be light in the bulb.
RGB vs RGBW vs RGBWW vs RGBCCT vs RGBIC
This series of abbreviations can be confusing for those who want to buy an RGB LED product. But don’t worry, the differences between them are slight. You have known that RGB stands for red, green, and blue, then let’s learn what the other words mean.
RGBW: red, green, blue, and white
RGBWW: red, green, blue, white, and warm white
RGBCCT: CCT means Correlated Color Temperature. An RGBCCT LED contains red, green, blue, cold white, and warm white.
RGBIC: IC means Independent Control, indicating a chip that can control colors independently.
The following is a detailed introduction to these types of LEDs.
RGBW: Compared with RGB, it adds a white light chip and therefore can produce more colors. Its most impressive function is to create a brighter and purer white color than that made by RGB LED.
RGBWW: There are 5 chips in an RGBWW LED. Based on the constitution of RGBW, it adds warm white color. This warm white light enables it to create a yellowish-white color, which RGBW can not achieve.
RGBCCT: Unlike adding white and warm white lights, RGBCCT has cold and warm white lights, thus can easily change the tint of white. Cold white light is more blueish and warm white light is more yellowish. The white color of the middle hue is closer to daylight. Cold and warm white lights have their own uses.
RGBIC: It is predominant in its performance in creating light effects. To achieve this, the independent control chip plays an important role. It makes the control of segmental colors possible. With its independent control, an RGB LED strip can show different colors and vivid light effects.
Control of RGB LED lights
How to control RGB LED to achieve different colors and light effects? Learn the following secrets and you will have an overall comprehension.
Analog and digital RGB LED
RGB LEDs can also be divided into analog and digital ones since these are the two main methods to change the current of LEDs. To be specific, analog control means constant current reduction (CCR), and digital control is pulse-width modulation (PWM).
Analog dimming is achieved by changing the current in the LED circuit with the hardware. With light and the power supply voltage remaining unchanged, it can achieve changing the brightness of the LED by changing the resistance values. Analog dimming makes the current continuous. But since the values of the hardware are limited, the range of adjustable current is also limited. When lighting of high precision is required, this approach is not ideal.
Digital dimming, also known as PWM dimming, is to change the on and off time of the current by sending digital signals to achieve brightness adjustment. Human eyes are not sensitive enough to brightness flicker. So PWM turns on and off of the LED at an extremely high frequency. If the frequency exceeds 100Hz, what human eyes see is the average brightness, instead of perceiving the fact that the LED is flashing. PWM changes the brightness by adjusting the time ratio of brightness and darkness. Because within one PWM cycle, when the frequency is greater than 100 Hz, people’s perception of the brightness is a cumulative process. The longer time the LED lights up in one entire cycle, the brighter the human eye perceives it. However, it is possible to capture the instant when the LED is dark with high-frequency sampling devices, such as high-frequency sampling cameras.
Both the above methods have their merits and demerits and need to be applied according to the specific situations. But PWM is the one being widely used at present.
Different principles are applied together with different signaling protocols. Some protocols include Phase control dimming, 4-wire (0-10V) dimming, Digital Addressable Lighting Interface (DALI), DMX, etc. These protocols vary in the voltage and current needed, the way to connect circuits, functions, and so on. There will be processors and drivers in the LED circuits to decode signals and then realize changing brightness or various effects of the lights. For instance, below is the structures of the system using the DALI protocol.
What users do
You can click the buttons on the controller or use applications on your phone to send signals to the receivers. The process of transmitting signals implements common technology like RF or IR, Wi-Fi, Bluetooth, etc.
This passage is an introduction to what is RGB LED, what are its classifications of it, and how it works. Hope that by viewing this passage, you can grasp the basic information of RGB LED and won’t be that confused when choosing different products. Thanks for your reading.