LED 라이트 디밍 시스템 번역(영어 번역본)1 Introduction
Due to the development of recent semiconductor manufacturing technology, LED(Lighting Emitting Diode) is receiving attention as a new light source to replace existing ones due to improvement in its electrical characteristics and reduction in cost. LED is environment-friendly and has a longer lifespan compared to other existing light sources. Also, it is advantageous in saving energy due to its high light efficiency. Because it is a semiconductor device, it has excellent electrical traits especially compared to existing light sources and therefore, can increase the energy saving effect by integrating a dimming control system.
Such dimming control systems are generally designed so that the user can control the brightness of the LED light using wired/wireless communication. However, making a system that uses wired communication has a drawback because separate communication lines are added and the installation cost increases. When using wireless communication, separate lines are not necessary but a communication modem that sends and receives wireless signals is added, raising the cost to make it difficult to be utilized in a home or office environment. In addition, existing dimming control systems have bad compatibility because they have different communication protocols depending on the modem they use. This paper aims to solve these problems by describing a dimming controller that controls LED light brightness not wit separate communication lines or modem, but by turning on/off a light switch. 2 Body
2.1 How It Works
Figure 1 displays the general system diagram of the LED light dimming controller using a light switch. The system is consisted of a SMPS which supplies power to the LED, a light switch to turn on/off, and a dimming controller that controls the brightness of the LED based on the on/off counts of the light switch.
Figure 1. General system diagram Figure 2 displays the internal block diagram of the dimming controller. SMPS supplies power to the MCU, and wave patterns of the AC input signal are sensed by the MCU. Through the inputted AC input wave patterns, the on/off count of the light switch is detected. This is used to control the brightness using PWM by turning on/off the FET, which is connected to the LED output. Figure 2. Internal block diagram of the dimming controller Figure 3 shows the wave patterns of the dimming controller based on the on/off of the light switch. When the switch is turned on initially, the LED brightness is maintained at maximum value because the MCU runs in its initial state and permits a high state on the FET’s gate voltage(Vgate). If the switch is turned back on within a given time(TDim) after the switch is turned off and on/off is repeated 2 or more times within a given time(TReset), it will be recognized as a dimming control signal and permit a PWM signal at Vgate. This causes the current flowing through the LED to repeatedly go on/off and lower the brightness. Also, the number of times on/off is repeated within the given time(TReset) is counted and the LED brightness is reduced in a phased manner by reducing the duty of the PWM signal at Vgate.
Contrarily, if the switch is not turned back on within the given time(TReset) after being turned off, power supply to the MCU and LED is suspended and eventually the LED is turned off. Figure 3. Major wave patterns of the dimming control system 2.2 Measurement Results
Table 1 shows the measured values of input power and luminous flux based on on/off count when using the proposed dimming control system for 10W, 30W LED down lights and 50W LED flat light respectively. Step1 shows maximum load, Step2 shows the measured value when the on/off count is 2, Step3 shows the value when the on/off count is 3. 3 Conclusion
This paper described a dimming control system that controls brightness using only a light switch. The proposed dimming control system does not require separate communication lines and modem, and was empirically proven to phase control the brightness of LED lights solely based on the on/off count of the light switch.
With the dimming control system proposed in this paper, we believe that additional construction time and cost for dimming control system can be drastically reduced, and it will be suitable for home and office environments due to its superior compatibility with existing light switch and lamp control. | 