具可調色溫與亮度的LED照明之驅動電路設計與研究

本文主要針對具可調色溫的LED照明燈具之設計與研究進行量測分析。傳統上的各式燈源，受限於燈體本身的發光特性，只能以單一色溫作表現，如白熾燈僅能產生暖白，螢光燈管的色溫選項也大都侷限在常見的晝光色(冷白光)與燈泡色(暖白光)，色溫的選擇性往往需要透過不同的燈源才能達成，且效果有限，LED為新世代的革命性光源，具備低耗電、體積小、重量輕、壽命長、無汞、反應速度快、可調光控制等優點；因此利用其不同LED的色溫組合，即可在燈泡或小燈具內實現色溫變化的可能性。然而色溫的變化往往產生亮度的改變，亮度的變化也牽動色溫的漂移，而不同效率的LED組合也造成控制上的難度，故如何有效的結合電路驅動設計與LED特性，使其色溫能精準地控制，是一重要的技術。目前照明用的LED大多採用多晶封裝(COB)或者是多顆LED為主，本論文針對雙色多晶封裝的LED，燈具則選用筒燈作為量測用燈具，電源則選用PWM Driver，透過PWM控制訊號20%、40%至100%的工作週期(Duty cycle)設定，改變LED電流導通與不導通的比例，藉此量測其不同工作週期比例之光通量，再將量測到的光通量做為韌體的參數設定，透過程式去校正色溫與亮度，使調整亮度時色溫不變；調整色溫時亮度不變之優質光環境。本文主要從LED的特性，與電路的比較，分析其不同的調變方式所產生的影響，探討色溫控制的具體實現方法，期能創造可隨應用場合而搭配的可變色溫燈具，使光源能夠更豐富生活。

關鍵字

LED ；室內照明；筒燈； PWM調光

並列摘要

The thesis studies how to design the adjustable color temperature of LED lighting fixture and analysis the characteristics based on the measurement experiment. Traditional lamps only emit single color temperature due to the light emitting principle. For example, the incandescent lamp is warm white and the compact florescent lamp is cool or warm white depend on its phosphor. It needs multi lamps to create the color temperature environment what we want. However, this effort is not good enough to change it by user control friendly. LED is a revolution light source with small size, low power consumption, less weight, long lifetime, no mercury (Hg), quickly response and easy dimming. So we can take various color temperature of LEDs to mix the desired color temperature in a compact space of bulb and lighting fixture. The major issue is brightness would be change by tuning color temperature. Meanwhile, the color temperature also be shifted by changing brightness. It is difficult to control brightness and color temperature independent, especially in various light efficacy for cool and warm white LEDs. The topic study filed is how to implement the highly accurate control system and combine the driving circuit with understanding the LEC characteristics. The trend of general LED lighting is adapted from the chip on board to integrated the adjustable color temperature lighting. This thesis is focus on to study the characteristics of COB and choose the down light to operate the measurement experiment. In order to improve the driving linearity, the PWM function is necessary for power driving circuit. We could measurement the luminous flux by various duty cycles and check the relationship of the cool and warm white ratio. The calibration parameters would be determined by analysis measurement data. According to the calibration parameters, the software could be embedded it and control the adjustable color temperature independently. The trend of general LED lighting is adapted from the chip on board to integrated the adjustable color temperature lighting. This thesis is focus on to study the characteristics of COB and choose the down light to operate the measurement experiment. In order to improve the driving linearity, the PWM function is necessary for power driving circuit. We could measurement the luminous flux by various duty cycles and check the relationship of the cool and warm white ratio. The calibration parameters would be determined by analysis measurement data. According to the calibration parameters, the software could be embedded it and control the adjustable color temperature independently. This thesis analyzes the influences of various parameters with PWM method and compares to the driving circuit with LEDs. The color temperature LED lighting method could be implemented. We believe it would make the life better with abundant color temperature light environment.