For example, five signal-processing functions are required for the LCD TVs currently being developed at Mitsubishi Electric Corporation. Technologies for Y/C separation, noise reduction, and IP conversion are essential. Additionally, compression feed-forward driving (cFFD) techniques improve video responsiveness, while natural Color Matrix (NCM) technology provides natural color reproduction with vivid colors. The new TVs also incorporate other functions, two are which being developed by Renesas: support for text broadcasting systems from different countries and an LCD-panel timing controller (TCON).

Previously, it took from two to six separate LSI devices to implement these seven functions. To simplify TV designs and cut costs, Mitsubishi Electric and Renesas have collaborated to develop the "digital video processor-multi" (DVP-M) series of video signal processing ICs. These complex devices are the first in the world to provide all of the previously mentioned technologies in single-chip solutions that deliver outstanding functionality and enhanced capabilities.

The DVP-M series LSIs eliminate or greatly reduce the problems of blurred color and after-images previously associated with LCD screens. Additionally, they save circuit-board space, cut power consumption, reduce parts counts and decrease overall cost. Figure 1 compares the old design with the new one.

One example relates to the depiction of diagonal lines, which has been a weak point for LCD TVs. Contour correction technology that analyzes the characteristics of diagonal lines is used to improve the sharpness of contours. Generally, the signal processing of diagonal lines has consisted only of comparing vertically adjacent pixels and checking along the time axis. The new video signal-processing ICs do more. To improve the image, they apply technology that reduces edge widths by checking edge regions three-dimensionally, including diagonally adjacent pixels. The right-hand side of photograph 2 shows the resulting gain in image quality.

Another example of Mitsubishi Electric’s expertise is the use of cFFD technology to improve responsiveness and deal with the problem of after-images caused by the display screen's slow response speed. According to Masaki Yamakawa of Mitsubishi Electric's Advanced Technology Research Laboratory, "The cFFD technology optimizes the voltage applied to the LCD to boost response speed by comparing the 'before' and 'after' images when a change in image content means that a quick response is required. The result is a response speed of 12 to 14ms, which improves after-image performance to a realistic level. The cFFD technology also uses image compression techniques to reduce the required memory size to a level that makes it possible to integrate the circuitry on a single chip.".

Another feature of DVP-M series is that the devices provide video interfaces for three different broadcast standards: NTSC, PAL, and SECAM. This simplifies the process of developing LCD TVs for different regions of the world.

To enable a wide range of end uses, from standard to high-end TV models, the LSI product range is split into three separate types of signal processing devices:

All devices in this product line have the same pinouts for complete mechanical compatibility. Mr. Yamakawa comments that "because the chips are pin-compatible, a common platform (circuit board) can accommodate all three models in the DVP-M series. This reduces the cost and shortens the time required to develop a wide range of LCD TVs, from standard models to premium products."

The Renesas SIP technology that makes the pin compatibility possible has the added benefit of reducing the amount of wiring on the circuit board. In turn, this reduces issues related to electro-magnetic interference (EMI), easing system design.

Having established a successful collaboration, Renesas and Mitsubishi Electric will continue to work to facilitate the evolution of LCD TVs. Both firms are contributing their expertise for tuning the parameters of advanced DVP-M chip implementations.