Microsoft has issues invites to the press for a media event on Sept. 23 in New York, where it is expected to unveil the new Surface 2 tablets. Reuters

Undaunted by sluggish sales of the Surface RT and Surface Pro tablets, Microsoft (NASDAQ:MSFT) is preparing to release a second-generation model of the device, the Surface 2.

The Redmond, Wash.-based technology giant has sent invitations to the media for a special event on Sept. 23 in New York, where it will unveil the Surface 2 and the Surface Pro 2 tablets -- the updated versions of the existing Surface RT and Surface Pro models.

Although the company was recently rumored to launch a Surface mini tablet soon, sources have said that such a product will not be part of the upcoming event, The Verge reported. According to the report, the Surface 2 and Surface Pro 2 will feature a two-stage kickstand, but the main form factor of both new tablets is expected to be very similar to that of the current models.

Microsoft Surface 2 event invite. Microsoft

The Surface 2 is rumored to feature a 1080p display and is likely to be powered by Nvidia's (NASDAQ:NVDA) Tegra 4 processor. The device’s battery is expected to last for about eight hours, while a new Power Cover accessory is likely to boost its battery even further.

When it comes to the Surface Pro 2, the tablet is expected to sport Intel’s (NASDAQ:INTC) new Haswell processor, and is likely to be shipped with 8GB of RAM. The Haswell processor is said to improve the battery life of the Surface Pro 2 by just more than two hours. The Power Cover accessory will also likely support the Surface Pro 2.

Microsoft recently cut prices across the Surface Pro lineup by $100 in the hope of increasing sales. The 64GB and 128GB versions of the tablet now cost $799 and $899, respectively.

According to recent data, Microsoft’s share of connected device sales has collapsed from more than 90 percent in 2009 to less than 25 percent today. Even departing CEO Steve Ballmer has admitted that the Surface tablets could not perform as expected.

“We built a few more devices than we could sell,” Ballmer said at a recent meeting with investors in July. “We’re not selling as many Windows devices as we want to.”