Irvine’s Vizio Inc., which designs and markets flat TVs here, grew its market share in the first quarter, extending its lead as the biggest seller of liquid-crystal display sets in North America.

The company sold 1.5 million TVs in the quarter for a total North America market share of 21.4%, according to data released this month from DisplaySearch, a unit of Port Washington, N.Y.-based NPD Group Inc.

That’s up 46% from a year earlier as Vizio had four of the top five selling LCD models in the U.S., according to Portland, Ore.-based Quixel Research LLC.

It took share from big-name competitors, including Samsung Group, Sony Corp. and Funai Electric Corp., which sells sets under the Philips brand in the U.S.

No. 2 Samsung sold 1.2 million sets and had 16.6% share. No. 3 Funai sold 884,000 and had 12.1% share. No. 4 LGE sold 783,000 for 10.7% share.

Rounding out the list were No. 5 Sony, No. 6 Sanyo Corp. No. 7 Toshiba Corp., No. 8 included a mix of TV makers, No. 9 Sharp Electronics Corp. and No. 10 Panasonic Corp.

Vizio sold 6.9 million TVs in 2010 for a total North America market share of 18%, according to DisplaySearch.

Vizio also topped Samsung in the light emitting diode, or LED market, selling nearly 733,000 units for a North American market share of 29%.

Samsung sold 582,000 LED TVs for a market share of 23%.

Vizio started in 2002 amid the flat-screen boom and now has yearly sales of about $3 billion.

It does all the product design, engineering, marketing and customer service locally. Most everything else is done in Asia.

Vizio sells its TVs at Costco, Wal-Mart, Target, Best Buy and other big box retailers.