Mitsubishi Electric Develops 'Laser Backlight LCD TV'

Feb 17, 2011
Takuya Otani, Nikkei Electronics
The new LCD TV (left) and Mitsubishi Electric's existing LCD TV using white LED backlight. They are 46-inch models.
The new LCD TV (left) and Mitsubishi Electric's existing LCD TV using white LED backlight. They are 46-inch models.
[Click to enlarge image]

Mitsubishi Electric Corp developed the "Laser Backlight LCD TV," which uses laser diodes for part of its backlight source, and prototyped a 46-inch TV.

Its backlight unit includes two types of light sources: red laser diode and cyan LED. Compared with Mitsubishi Electric's existing LCD TVs, which use white LEDs for backlight, the color gamut of the new TV is about 1.3 times wider. It is a 126% color gamut on NTSC standards.

"Especially, the vividness of red color has drastically improved," the company said.

Mitsubishi Electric has already commercialized a rear projection TV using RGB color lasers (See related article). This time, the company used only the red color laser.

"We took costs into consideration for commercialization," it said. "And we found that the red color laser is more effective than the other lasers."

The laser is manufactured by Mitsubishi Electric. Its emission wavelength is 638nm.

Because red color is realized by the laser light source, cyan LEDs are used for the other two colors (cyan is a mixed color of green and blue).

"If green and blue colors are realized by two kinds of LEDs, it causes the unevenness of color," Mitsubishi Electric said.

The cyan LED is a customized product ordered for the new LCD TV, it said.

The backlight of the prototyped 46-inch LCD TV is the edge-lit type. It uses several tens of the red laser diode and several hundreds of the cyan LED. Because a laser and an LED have different divergent angles, Mitsubishi Electric developed an optical system for evenly mixing lights from them. As a result, the unevenness of color was mitigated, the company said.

The brightness, contrast ratio, power consumption and other specifications of the new TV are almost the same as those of Mitsubishi Electric's LCD TVs using white LED backlight, it said.

The company plans to commercialize the Laser Backlight LCD TV within fiscal 2011 and release it in Japan first.