Global television shipments in the second quarter rose 11% from a year earlier to 47.5 million units, NPD Group unit DisplaySearch said today. North American flat-screen TV sales surged in advance of February’s U.S. switchover to all-digital broadcasts, while customers in developing regions exchanged cathode-ray tube TVs for liquid-crystal display sets.

Year-over-year growth accelerated from 1% in the first quarter as second-quarter liquid-crystal display and plasma shipments jumped 47% and 52%, respectively, according to DisplaySearch. Samsung lengthened its lead over No. 2 Sony in global market share by revenue.

About 57% of the TV sets sold in the quarter were flat-panel TVs. LCDs accounted for almost a third of the TVs sold in developing regions, while closely held Vizio and Matsushita’s Panasonic sold plasma TVs at sizes that weren’t available a year earlier. LCDs accounted for 80% of the TVs sold in North America.

Samsung’s unit sales jumped 52% from a year earlier, giving it a 23% global market share by revenue. Panasonic, the world’s biggest plasma TV maker, leapfrogged Sharp into the No. 4 position globally among all TV types as plasma TV unit sales tripled in China.

Last week, DisplaySearch reported that North American television shipments in the second quarter jumped 28% to 9.3 million units from a year earlier, marking the largest jump in at least four years and defying the U.S. economic downturn. The North American jump, the largest year-over-year increase since DisplaySearch started tracking shipments in 2004, was fed by a 34% rise in plasma TV shipments.

In June, DisplaySearch said 2008 global TV shipments would jump 4% to 208 million units.