Acer today unveil 3 new tablet devices to challenge iPad. Two of them uses the Android OS and they come in 7″ and 10.1″ screen. The third is based on Windows 7 and uses a 10.1″ screen.

Acer joins a field dominated by Apple, which had a 95 percent share of the tablet market last quarter, according to Strategy Analytics. Samsung Electronics Co. recently released its Galaxy Tab and RIM plans to release its 7-inch BlackBerry PlayBook next quarter.

The two Android tablets will be available in April and the Microsoft device will go on sale in February. All three will offer Wi-Fi connectivity and allow users to surf the Internet using a 3G connection. Wong said the tablets would likely be in the previously stated range of $299 to $699.

Acer yesterday also released a smartphone with a 4.8-inch screen based on Android.