Sony is expected to announce a new Sony Digital SLR as part of its Alpha range in the coming weeks if an invite for an event in America turns out to be true.

SonyAlphaRumours.com, which as you might expect covers rumours about Sony Alpha cameras has got wind of an NDA briefing event that states:

"Featuring never before-seen Sony Digital SLR products and soon-to-be released Sony Digital Imaging models"

The event, which is happening on Tuesday 24 August 2010, will be under a non-disclosure agreement meaning that although Sony will be showing select members of the press the new kit, the actual launch date could be some time in the future, possibly as late as camera trade show Photokina in September.

Photokina is a once every 2-years event held in Cologne and is expected to see launches from Fujifilm, Canon, Nikon, Olympus and others.

SonyAlphaRumours are suggesting that the new models could feature a fixed mirror design.

"Unlike current DSLR who's mirrors move up and out of the way to take a picture, a Pellicle or Pellix mirror stays in place," describes NikoDoby over at Nikonrumours. "It's semi transparent so the image is projected up into the viewfinder and transparent enough to allow the sensor to be exposed. The advantage is 10fps or more and the sensor is protected from dust. It's also inherently quiet since there's no mirror slap. The disadvantage is a dimmer viewfinder and a small loss of light to the sensor (2/3 stop?). Also the mirror has to be spotless now since the photo is exposed through it."

What do you think Sony will launch?