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.