【作者】 韩东；

【导师】 吕国强；

【作者基本信息】 合肥工业大学 ， 精密仪器及机械（专业学位）， 2015， 硕士

【摘要】 液晶显示技术经过多年的发展,已经成为主流的平板显示技术。液晶不发光,需要背光源提供光线照亮显示区域。由于液晶的漏光现象,对比度不高成为液晶显示器的一个无法克服的问题。液晶显示的另一个固有问题是能效。液晶显示器通常工作时,即使显示全黑图片,背光也工作在最亮状态,无谓的消耗能量。动态调光技术能够根据液晶电视的显示内容动态地调整背光源亮度,同时对液晶像素进行补偿,有效降低整机功耗的同时提高了显示对比度。本文首先介绍了动态调光技术并分析了国内外现有动态调光算法的优缺点,然后提出了基于S曲线的两级动态调光算法,介绍了适用于稀疏型直下式背光源的区域动态调光算法,进行了调光算法的硬件方案设计,设计并制作了FPGA调光主控板和LED背光源驱动电路板,最后开发了整体工程样机。针对国内外现有的全局动态调光算法节能率低且存在溢出失真现象,本文提出了基于S曲线的两级动态调光算法。首先根据图像中像素亮度的最大值进行线性放大,然后基于亮度变化后的图像特征值确定S曲线参数,据此得到背光调光后的亮度和液晶像素补偿系数。为了增加电路设计的通用性,针对全局调光算法和区域调光算法,设计了具有图像存储机制的FPGA主控板,合理划分了功能模块,对各模块进行了RTL级描述,合理平衡了硬件资源利用率和处理速度。针对2种调光算法,分别开发了液晶电视工程样机,并进行了测试。测试结果表明50英寸的全局动态调光LED液晶电视整机节能18.4%,32英寸的区域动态调光LED液晶电视节能25.2%。两台工程样机稳定工作,显示品质均明显优于没有调光的普通电视。更多还原

【Abstract】 After more than 30 years development, liquid crystal display (LCD) has become a mainstream technology for flat panel displays. LCs don’t emit lights; therefore backlight units (BLUs) are necessary. Caused by light leakage of LC cell, low contrast ratio (CR) is one big drawback for LCDs. Another shortcoming of LCDs is power efficiency. The luminance of a BLU is constant, which means the power is consumed even displaying a completely dark image. Based on the display image, the backlight dimming technology can dynamically dim the backlight luminance and simultaneously change the LC pixels grayscales to, which can increase the contrast and reduce power consumption.The thesis introduces the dynamic dimming technology and analyzes the pros and cons of the nowadays dimming algorithms. The S-curve-based tow-step dimming algorithm for global dimming is proposed. The local dimming algorithm for sparse distributed LED backlight is introduced. The hardware design scheme for both the global and local dimming algorithms is then introduced. FPGA dimming board and LED backlight driving board are produced. The 2 prototypes are developed.As the fact that nowadays global dimming algorithms present the disadvantages of low power saving ratio and overflow distortion, the proposed algorithm is based on S curve, containing 2 steps. The grayscales of all the pixels are firstly linearly amplified, based on the max value of the pixels. The parameters of S curve are then decided on the modified image. The dimmed backlight level and the coefficient to compensate the LC pixels are confirmed.To increase the versatility of the circuit design, the hardware circuit is designed suitable both for global and local dimming algorithm. The FPGA main board is based on image storage. Several function modules are created and described on RTL level, which can reasonably balance the hardware resource efficiency and processing speed.Two prototypes to realize the proposed global and local dimming algorithms are developed and measured. The measurement results show that the ratios of power saving are 18.4% and 25.2%, respectively for the global dimming LCD TV of 50 inch and the local dimming TV of 32 inch. Both the 2 prototypes work well and present better display quality than the no-dimming LCD TVs.更多还原