According a press release issued by the Redmond, Wash.-based company, ViewSonic will pay royalties under the agreement, which also covers the Chrome platform, as noted by the Seattle Times. Microsoft's statement regarding the Acer deal doesn't specify whether royalties are involved in its patent license agreement.
It has been reported that the Windows maker currently makes more money off of patent licensing to Android vendors than it does off its own Windows Phone 7 platform. HTC reportedly pays as much as $5 per Android device sold to Microsoft.
In July, Microsoft announced that it had reached four new Android patent deals. Wistron Corp, Velocity Micro, General Dynamics and Onkyo Corp have all signed agreements with the company.
For its part, Acer has said it will face any patent infringement challenges that come with the Android platform. Chairman JT Wang has accused Apple of starting a "patent war" with HTC over Android.
Last month, Microsoft and Google executives exchanged tense words over the current patent situation. The spat began when Google's chief legal officer complained that Microsoft, Apple and others have conspired against the company by banding together to buy up patents from Novell and Nortel. Microsoft fired back by asserting that Google had declined an invitation to join the Novell consortium.
"Google says we bought Novell patents to keep them from Google. Really? We asked them to bid jointly with us. They said no," Microsoft General Counsel Brad Smith said on Twitter.
Google CEO Larry Page said in August that it had purchased Motorola to "protect Android from anti-competitive threats from Microsoft, Apple and other companies." The company announced the deal to acquire Motorola, which has more than 17,000 patents, for $12.5 billion last month.
Meanwhile, Apple's legal battles against Android vendors such as Samsung and HTC continue. Earlier this week, HTC sued Apple again with patents it had obtained from Google. Apple has been successful in obtaining a number of injunctions against rival Samsung's Galaxy line of tablets and smartphones.