Sharp Develops New IC to Introduce Color Displays into White Goods
Sharp Corp announced the "LR35503" graphics controller IC, which integrates circuits for graphics drawing, LCD control and CPU core, etc.
"If a color display is used, the amount of information shown and the quality of its expression will increase significantly," said Eiji Ikuta, assistant department general manager of Product Development Dept II of Sharp's System Device Division. "The cost of the components required for a color display, however, has been too high. We have integrated the minimum functions needed to enable white home appliances to feature a color display into a single chip."
Sample shipments and volume production are slated to start in mid September and October, respectively. Sample pricing is ¥3,000 (approx US$28).
The first product that employed the "LR35503" was the "AX-X1," a new model in Sharp's "Healsio" superheated steam oven series announced Sept 1, 2008. The oven can display photos of cooked recipes and information about the effects of its cooking technology (which removes oil from food) using its GUI, changing the content displayed on the color LCD panel in accordance with the operation of the dial and buttons.
Employing a color LCD with minimum cost increase
"If we raise the LR35503's processing performance more than necessary, its cost will increase and the barriers to the adoption of a color LCD won't be lowered at all," said Masashi Shiomi, assistant manager of the Planning Department in the System Device Division in Sharp's Electronic Components and Devices Group. "We focused on how far we can limit its functions to minimize a cost increase caused by the introduction of a color display."
The LCD controller only supports QVGA (320 x 240 pixels) displays, which are relatively inexpensive, and displays images by decoding JPEG files to cut a memory volume. In addition, to use a dual-layer substrate, Sharp made the LR35503 a 0.5mm-pitch QFP package.
"(Thanks to those efforts,) the cost of the components excluding the display is almost equivalent to that required when using a dot matrix LCD display," Ikuta said.
The 27MHz "Z80" core, a JPEG codec circuit and a graphics drawing circuit are integrated. The graphics drawing circuit can display a 16 x 8 to 320 x 240 resolution still image, a background image with a maximum resolution of 512 x 256 pixels (partially cut out when displayed), and up to 64 frames of 8 x 8 or 16 x 16 resolution image patterns at a specified coordinate at 30fps.
"Like old game consoles, it expresses preinstalled image patterns by lining them up like tiles," Shiomi explained.
The chip supports special effects such as fading and bi-level images as well. Featuring a circuit for inputting digital video signals in the ITU601 specification, it can also overlap and display graphics and images input from a camera.
In accordance with user operation, the Z80 core determines what image data will be displayed at which coordinate, and it transmits the coordinate data and the image's memory address to the graphics drawing circuit. As it only requires relatively easy computing, Sharp could set the CPU core's operating frequency as low as 27MHz, it said.
The graphics circuit, which receives that information from the Z80 core, takes data from external flash memory, in which the image data is stored and draws it on the display after decoding its signals according to the JPEG standard using a dedicated circuit. As this system requires no external video RAM, the LR35503 can reduce component costs, Sharp stated.