| Now, LCD has been were widely used in many aspects, is one of the most commonly used display devices in our daily life. However, due to the light leakage of its backlight module, which it requires to display, LCD gets lower contrast ratio compare with other types of display devices. In order to solve this problem, LED dynamic backlight technology has been proposed by some researchers. With the help of LED backlight module, this technology dims the luminance of the backlight when LCD is displaying some dark images. In this way, the light leakage can be reduced and the contract ratio can be improved. And, the power consumption can also be reduce, too. For the outstanding performance of the LED dynamic backlight technology, it has been given more and more attention.LED dynamic backlight, especially the block dynamic backlight needs to increase the number of the drivers and control circuits, to control the luminance of each block, and, the production costs get higher. So, many researchers are focusing on how to get better display with lower costs. For block dynamic backlight, the more blocks it has, the better effect it gets. As each block needs an additional driver to control its luminance, the cost grows with the number of the drivers. Getting better display effect with the array of small-scale backlight blocks, as well as controlling the array of large-scale backlight blocks with a more simple circuit are two major directions of the subject. And the current studies are mostly the former. In this article, a block dynamic backlight control method based on a orthogonal decomposition is proposed. In this method, the matrix of the luminance of each block in the backlight array can be decomposed into2binary signals by2D discrete Hadamard transform. A matrix-structured backlight system is designed to realize this control method, and the basic control procedures are also given in this article.First, this article has described the principle of the LED block dynamic backlight and the clipping that exists in the display with the dimming backlight. The contradiction between the light leakage and the clipping is indicated.Second, this article has explained how X-Y channel local dimming method controls the array of backlight blocks with much less drivers. With the help of wavelet analysis, the defect of the X-Y channel local dimming method in displaying the diagonal high frequency information has been pointed.Then, through summing up the advantages and dis advantages of the various backlight algorithm above, a block backlight control method based on2D discrete Hadamard transform is proposed. This method utilizes orthogonal decomposition, to ensure the integrity of the high frequency information of the backlight, and discomposed each frequency into28-bit binary signals. A matrix-structured backlight system is designed to realize the Hadamard control method. Through the analysis of the time complexity of the control procedure based on the designed system, the feasibility has been verified.Finally, this article compares the backlight generated by the proposed method with others, verifies the practical effect of the Hadamard block dynamic backlight control method through. |
