Low-temperature polysilicon (LTPS) LCDs feature higher electron mobility than amorphous-silicon displays. As a result, it's possible to fabricate driver circuitry together with pixel transistors on their glass substrates. Toshiba engineers added a static random-access memory (SRAM) cell to be fabricated in each dot of the LCD to give the display memory function.

Since the embedded memory holds the data, there is no need to apply an electronic field to the display once the still-image data is written. This will cut power consumption greatly, said a Toshiba spokesman. The prototype LCD dissipates 1.3 milliwatts when it shows still images and consumes 25 mW when displaying moving images in 4,096 colors.

The 1-bit SRAM cell, which consists of seven transistors, holds "on" or "off" data for each red, green and blue dot. It is fabricated under the reflective electrode of each dot.

"The target of this development is to cut the power consumption of cellular phones in the standby mode," the spokesman said. Toshiba intends to promote the LCD for next-generation cell phones that will handle power-consuming color video.

The prototype LCD will cut power consumption by 50 percent during still-image display, according to Toshiba. If the LCD is used in cellular phones equipped with a battery with 3.7-volt output and 650-mAh capacity, the standby time can be extended by 23 percent, from 350 hours to 430 hours, said Toshiba.

The sample will be available in the second quarter of next year. Volume production is to follow in the third quarter of 2001. But that's too late to make it into the first third-generation cell phones to hit the Japanese market, units based on wideband-CDMA technology that are expected here next spring.