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FROM EDN EUROPE: Reference designs boost display quality for portable products

With Electronica approaching, the president of Sharp Microelectronics in Europe, Maximilian Huber, recently charted some of the pressures on the LCD business. He noted the developing trend of camera functions in mobile phones that more closely approach the performance of stand-alone digital cameras. This trend, combined with mobile phones' increasing multimedia capabilities, implies a demand for better display quality. Sharp is using its CGS (continuous grain silicon) silicon technology in phones and expects to soon offer transflectives—for better performance in sunlight. At the other end of the scale, Huber acknowledges the price pressure in the LCD-television sector, with plasma-technology suppliers continuing to offer competition in the largest screen sizes. Sharp says it has the only "sixth-generation" LCD production facility currently running; it handles "mother glasses"—the substrate on which the active devices for the display are formed—of 1500×1800 mm. Because the glass thickness is only 0.7 mm, you cannot manipulate these glass sheets by hand. Therefore, the manufacturing infrastructure to handle the glass represents a significant investment in automated production.

Huber also acknowledges another pressure on the displays business: the Reduction of Hazardous Substances directive. Its greatest immediate impact on displays is in the provision of backlighting, which manufacturers have predominantly carried out with cold-cathode fluorescent tubes. Because these tubes are mercury-based, manufacturers must replace them. The two main candidate technologies for use are Xenon-based lamps and white—or colour-balanced cluster—LEDs. (Exhibitors at Electronica will offer both solutions.)

Sharp continues to develop its System-LCD concept. The CGS process allows the formation of semiconductor devices of good performance (speed) directly on the substrate glass along with the active transistors of the LCD matrix itself. Drivers, controllers, and power-supply functions can be integrated on to the periphery of the glass panel, reducing component count, size, and weight of the complete display. The company's Advanced TFT design uses the metalisation of the conductive tracks interconnecting the thin-film transistors as a reflector to return incident light through the LCD matrix and to increase brightness in high ambient light.

At Electronica, Sharp will introduce a 10.4-in. display for the industrial market, the LQ104V1DW01, with 380- cd/m² brightness and a 500-to-1 contrast ratio. It employs
the ASV (Advanced Super View) generation of transmissive-technology display
panel and provides good viewing angle with no colour inversion (href="contents/images/468447f1.pdf">Picture).

Supporting its range of display products in the mobile market, Sharp also expects to augment its series of reference designs for PMPs (portable media players). Existing designs support low-end products at QCIF resolution (176×220 pixels) with an amorphous-silicon 2.2-in. display and an ARM9-based 200-MHz controller IC, as well as a medium-resolution platform with QVGA (320×240-pixel) resolution and, again, the LH7A404 controller. Expect the next step to be a high-end reference design with digital video record and playback capability that will provide mobile video at VGA (640×480-pixel) or D1 (720×480-pixel) resolution, for A/V enthusiasts and professional markets.

Sharp, www.sharp-sme.com.

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