Google has sent invitations for an event in San Francisco on Oct. 4 where the web company is expected to introduce new smartphones and home-automation hardware, along with product upgrades. The text of the letter, which includes the phrase "Ok Google, add to calendar," suggests a bigger role for the Google Now voice assistant. The invitation also features an animated graphic showing a search bar that morphs into the shape of a smartphone.

Google may stamp its latest smartphones with a "Pixel" brand instead of the "Nexus" name it has used in the past for Android smartphones it has made in collaborations with partners.

Google may also introduce a higher-resolution upgrade to its Chromecast media streaming device and new virtual-reality hardware. There are also reports that Google may ditch the Nexus brand for its phones; the company sent a tweet with the hashtag "madebygoogle."