Sony will soon launch a pair of professional monitors that contain the largest commercial OLED screens yet produced.

The monitors are aimed at the broadcasting industry. A model with a 25-inch screen will go on sale on May 1 and one with a 17-inch screen on July 1.

OLED is a flat-panel screen technology that can produce brighter and richer pictures than LCD panels. The screens contain an organic material that emits its own light when energized, so no back light is required. That also helps make the screens thinner and reduces power consumption.

Sony demonstrated the screens in Tokyo on Wednesday. The OLED monitor is on the left, a conventional LCD monitor on the right. It's alittle difficult to see on video, but the OLED picture was visibly superior. When the screen showed a dark image, the OLED went down to full black, but the LCD remained grey because of its backlight.

Like a lot of equipment used in the broadcasting industry, the new monitors won't be cheap. The 25-inch model will cost 2.4 million yen, that's almost 29,000 US dollars. While they appear expensive compared to consumer-grade monitors, the OLED screens cost only about 10 percent more than the LCD monitors they aim to replace.

Sony's launch of commercial 17- and 25-inch OLED monitors is a step forward for the display industry, which has made a habit out of promising large OLED screens then failing to deliver.

Sony put its first OLED TV, an 11-inch screen, on the market in late 2007, but has never followed it up with a second product. The company continues to show prototypes, like these concepts from 2009 or this flexible screen from 2010, but none have come to market.

Competitors including Samsung and LG Electronics have also shown prototypes, but are yet to produce OLED televisions.

That's because screen makers have had a hard time perfecting OLED production to reliably make large, flawless screens. Smaller size panels around 3-inches have proved no problem and are popular in portable gadgets, but larger screens have remained a hurdle.

The difficulty was most vividly demonstrated with Sony's OLED TV. Despite its small size, the set $2,500 US dollars.

As for whether the new monitors mean a larger OLED TV is one the way, on Wednesday Sony wouldn't comment.