The venerable CRT monitor may finally be on its way out as the primary display technology for critical broadcast and post production evaluation purposes.
Many factors, predominantly the European Union’s RoHS (Restriction of Hazardous Substances) directive that went into effect in July 2006 banning the use of six hazardous materials in the manufacture of various types of electronic equipment, have created a demand for a lead-free alternative to the cathode ray tube. Invented in 1897 by German physicist Karl Ferdinand Braun, the CRT has been a mainstay in television control rooms since the dawn of TV, but making them without using lead in their construction has proved impractical.
DISCOVERING THE DIFFERENCE
(click thumbnail)Now Sony, whose BVM (Broadcast Video Monitor) line of CRT displays has long been a popular monitor for broadcast engineers worldwide, has started shipping the screen they predict will become its replacement: the new BVM-L230 Master Series 23-inch LCD high definition “critical evaluation” monitor.
When prototypes of the BVM-L230 were displayed side-by-side with Sony’s BVM-A CRT screens at NAB2007, only the most golden eyes could tell the difference. Now, Discovery Communications has taken delivery of more than 25 BVM-L230 LCD displays to be installed in high end post production bays and media ingest operations rooms in the Discovery Creative Technology Center where broadcast productions and associated DVDs for The Discovery Channel and its sister networks will be produced.
“We had actually been looking at the BVM-L230 LCD displays even before Sony’s demonstration at NAB,” said Tony Cole, vice president of engineering for Discovery Communications. “Knowing that the RoHS restrictions would be eliminating CRT screens, we felt this was a perfect opportunity to adopt a monitor technology that would be more power efficient and require less space. We did an exhaustive investigation and determined that the BVM-L230 monitors would be an ideal replacement for the CRT monitors we had previously been using. In some cases they are actually better than what they are taking the place of.”
Now that Cole’s engineers are in the middle of installing the BVM-L230 LCD screens, he has found their performance exceeds expectations. “They are a definite advancement in display technology,” Cole said, “and we will be using them to replace all of our CRT monitors in the near future.”
He may not have any choice, if Cole wants to stay with the Sony brand. Due to many consumer-driven marketing factors in addition to the RoHS and similar manufacturing restrictions adopted by governments from California to China, Sony has decided to officially discontinue manufacturing CRT monitors although they will still sell their existing 14-inch and 20-inch inventory.
“The name BVM stands for a product that is quality driven,” said John Kaloukian, director of Sony’s Professional Display group, “so we decided there was no reason to move away from that nomenclature for our new LCD line. After all, the BVM-L230 monitors are geared toward the same target market.”
CONTROLLING BLACK LEVELS
Based on Sony’s Trimaster technology incorporating 38 exclusive patents, the BVM-L230 offers a 22.5-inch (viewable area, measured diagonally) screen, full 1920x1080 resolution, and is capable of producing 1,024 levels of gray scale. The BVM-L230 also boasts a color-gamut panel that is wider than their BVM-A CRT models, a newly developed high-precision backlight system and the industry’s first 10-bit driver.
“As the leader in this technology, we did not try to bring out an LCD-critical evaluation monitor until it was ready,” Kaloukian said. “For example, instead of the previous CCFL [cold cathode fluorescent lamp] backlights, the BVM-L230 uses 1152 LEDs (light emitting diodes) as its source of illumination for improved accuracy in its black levels.”
Black levels have historically been a concern when evaluating LCD displays. But although the black level from a conventional CRT varies with the ambient light from the environment in which they are viewed, the black level in an LCD can be completely calibrated which means it never varies. Since LCD screens use polarization to modulate the light, they reject the influence from surrounding light in the room where the display is mounted.
This makes the BVM-L230 especially applicable for installation in remote trucks, and Alabaster, Ala.-based Crosscreek Television Productions is finding them highly applicable for an OB truck’s unique requirements. John Peers, the company’s head of engineering is looking forward to putting BVM-L230s in the new Voyager 8 truck 53-foot HD Expando vehicle they are building.
“The racks we have designed in this truck are not big enough to support glass monitors,” Peers said. “But our tech manager and head video operator saw the BVM-L230 versus CRT comparison at NAB2007. Its colorimetry and black-level technology impressed them, and they knew this LCD monitor would fit in the rack space we had allocated for them.”
Among other assignments, the Voyager 8 will be used by ESPN to cover NHRA drag racing beginning in February 2008, so it has to be ready for HD production at any location. “Since we will be using all LCD displays in it, we wanted to make sure our main evaluation monitors were of the highest quality,” Peers said. “Our engineers have a very critical eye and the BVM-L230 fit their bill.”
The 23-inch BVM-L230 is priced at $25,000 which is $1,000 less than the previous 24-inch BVM-A CRT monitor. Sony will show a 42-inch version of the BVM LCD screen at NAB2008.
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