We have developed a new LCD controller incorporating a Compression Feedforward Driving, which will be second generation Feedforward Driving. In spite of having only one SDRAM, this LCD controller can offer nearly ideal performance, improving the response time through utilizing image compression technology to reduce the frame memory requirement.

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Abstract— The authors have been developing a Feedforward Driving scheme as an overdrive technique to improve LCD response time. Focusing on the reduction of frame memory in overdrive in particular, they are now studying a memory‐reduction method by applying an image‐compression technique. An LSI has already been developed that incorporates a Compression Feedforward Driving unit, which successfully reduced image data to 1/3 by means of the image‐compression technique. This paper reports a study of Motion Adaptive CODEC Feedforward Driving in which a motion adaptation process is added to the CODEC section of the Compression Feedforward Driving unit. This motion adaptation process reduces the amount of errors in overdrive that are caused by memory reduction by using a circuit of the same scale as that for Compression Feedforward Driving.

Methods of reducing overdrive memory using fixed block truncation coding (FBTC) have been studied since 2002, and the effects have been described from time to time. To date, our study has developed a timing controller for liquid crystal panels (TCON), and located in this panel, are a compression feedforward driving (cFFD) unit, which constitutes the basic structure, and a motion adaptive CODEC feedforward driving (macFFD) unit, which switches the structure according to the motion. Both driving units are available for the overdrive of 1/3 compressed images. Further in 2006, we proposed a high compression feedforward driving (hcFFD) algorithm for 1/6 compressed image overdrive. This paper reports the technology of hcFFD integrated into a single LSI, in which the performance has been improved and the circuit has been simplified through a review of the algorithm.

Abstract— The authors have studied a method of reducing the frame memory for signal processing used to improve the response time of liquid crystals. Compared with cases in which quantization is used, the compression Feedforward driving method, which reduces frame memory by applying an image‐compression technique, can effectively reduce the frame‐memory size. The study revealed that errors decrease by 6–10 dB or so if the image data was reduced to 1/3 by means of image compression. Based on the results of the study, the authors have developed a second‐generation LCD controller. With just one SDRAM unit, this LCD controller can produce almost ideal processing effects.

The algorithm to reduce the memory capacity in FFD (Feedforward Driving) is discussed. FFD improves the motion video on LCD. The application of image compression technology achieves approximately one tenthorder reduction of memory capacity.

Authors have been engaged in the development of a feed forward driving technique, as part of the overdrive technique to improve the response time of liquid crystal displays. They have developed, in particular, a compression feed forward driving system in which an image compression technique was applied, focusing on a method of reducing the frame memory necessary for the signal processing of overdrives. Further, they are now studying motion adaptive CODEC feed forward driving that reduces the amount of overdrive errors by adding a motion-adaptive process to the image decoding section in cFFD. This paper discusses macFFD that does not use SDRAM as the overdrive for entry model LCD TVs. Setting the image compression ratio to 1/10 or so will enable the fabrication of frame memory for overdrive for SDTV using SRAM. IntroductionImprovement of the performance of the display of motion pictures has been recently requested for liquid-crystal (LC) panels, in addition to the viewing angle, brightness, contrast and the gamut of color reproduction. This demand has been accelerated by users' comparisons of motion picture display performance between LC panels and conventional display devices, or CRTs, and is also driven by the fully-grown market of LC TVs.In recent years, a number of techniques have been reported for improving the performance of displaying motion pictures, such as the overdrive technique to improve the response time of LC display units, black insertion, blinking and back light to improve hold type problems, and so on [1-4].On the other hand, some new measurement methods to quantify blurs in motion pictures displayed on LC panels have been also discussed. It is said that motion blurs on LC panels are attributable to the long response time of LCs and the temporal summation by hold type displays. The study of a new definition of response time and a new method of evaluation has been promoted because the conventionally used definition of LC response time cannot properly express such performance factors of displaying motion pictures [5][6][7][8].Among others, we have been intensively considering a method of reducing the frame memory required by overdrive after the development of feed forward driving (FFD), which is our firstgeneration overdrive [1]. Compression feed forward driving (cFFD), which is our second-generation overdrive technique, has already been developed [9][10][11]. This cFFD realized maintenance of performance and cost reduction through reducing the frame memory required by overdrive by means of the image compression technique.Further, we have started the study of motion adaptive codec FFD (macFFD), in which a motion-adaptive processing unit is added to the image decoding section of cFFD, as the third-generation FFD. The use of the motion-adaptive processing function in the image decoding section enables us to restrain the occurrence of unnecessary acceleration data in still pictures, which is one of features of cFFD, and at the same time, to reduce acceleration data errors in motion pictures [12].In th...

We have developed High Compression Feedforward Driving (hcFFD) that can compress the image data stored in the frame memory of overdrive down to 1/6. Together with the optimization of the encoding parameters of macFFD, which belongs to the previous generation, this hcFFD technique corrects the response time of liquid crystal with smaller and less memory by means of a system that dynamically controls the bit rate allocated to the luminance signal and the color signal. This 1/6 reduction of image data allows us to structure a memory interface with a 16-bit data bus even on high-definition LCD panels, ensuring both low cost and secured performance.