• 한국멀티미디어학회논문지
• /
• 제22권8호
• /
• pp.860-873
• /
• 2019

LCD backlight boosting and the integration of boosting and dimming are proposed based on image analysis to maximize perceptual image qualities and to reduce display system power. Based on the histogram of the image data, methods for selecting an image suitable for boosting and for adjusting the optimum backlight brightness are proposed. A comprehensive combined optimization method of LCD backlight boosting, dimming and bypass based on image characteristics is also described. Perceptual image quality enhancement and power consumption are evaluated based on well known image databases. Average subjective image quality is improved by 24.8%, RMS contrast is improved more than 20%, and average power consumption is reduced by 15.94% compared to conventional uniform boosting.

• 전자공학회논문지SC
• /
• 제42권3호
• /
• pp.63-70
• /
• 2005

유도방전을 이용한 무전극 램프는 전극을 필요로 하지 않기 때문에 긴 수명을 갖으며 안정기 출력의 변화에 대해서도 매우 강한 특성을 갖는다. 본 논문에서는 무전극 램프 조광제어를 위한 두 가지 새로운 알고리즘을 제안하였고 이를 적용한 공진형 인버터에 대하여 기술하였다. 제안된 두 가지 조광제어 알고리즘은 주로 LCD 백라이트의 조광제어에 적용되는 버스트 디밍 기법을 기초로 한다. 제안된 두 가지 방식중 하나는 개선된 버스트 디밍 기법으로 간단한 디지털 논리회로를 이용한 제어회로를 통해 $5\%$ 단위의 시비율로 조도조절이 가능한 방식이며, 나머지 하나는 버스트 PWM 평균 시비율 제어 기법으로 다소 복잡한 제어회로를 통해 $1\%$ 단위의 시비율로 조도조절이 가능한 방식이다. 본 논문에서는 100W급 무전극 램프를 대상으로 실시한 실험결과를 통해 제안된 조광제어 알고리즘의 유효성을 입증하였다.

• 전력전자학회논문지
• /
• 제19권4호
• /
• pp.320-326
• /
• 2014

In this paper, the new smart dimming algorithm which is mixed with PWM and PAM control method is proposed for reducing the power consumption of LED TV Backlight. The proposed technique is using the curve characteristics of LED forward voltage and current which is proportionally changing LED forward voltage as changing LED forward current. Therefore, each PWM and PAM control method has different LED forward voltage and current in the same brightness condition. The PWM control method adjusts the brightness of LED TV Backlight by only varying the duty ratio of PWM and constantly sustaining the amplitude of LED forward current and voltage. So, the level of LED forward current and voltage in the PWM control method is relatively high and constant regardless of duty ratio of PWM. On the other hand, the PAM control method adjusts the brightness of LED TV Backlight by directly varying the level of LED forward current. So, the level of LED forward current and voltage in the PAM control method is lowered according to the brightness level. For the above-mentioned reason, the PAM control method has the advantage of reducing the total power consumption of LED TV Backlight at the brightness condition of below 100%, compared with PWM control method. By implementing this characteristic to LED driver circuit with control algorithm in MCU, the power consumption of LED TV Backlight can expect to be reduced. The effectiveness of the proposed method, new smart dimming algorithm, CPWAM(=Conditional Pulse Width Amplitude Modulation), has been verified by experimental results.