According to a study that was sponsored by Google, consumer usage of smartphones and tablets is on the rise, which should be fairly obvious to just about anyone. But the study also notes that increased smartphone and tablet usage has not caused consumers to abandon the personal computer. In fact, most of these users are comfortable using multiple device types, and far more smartphone users also use PCs rather than tablets at the moment.

"Mobile devices are mainstream," a post to the Google Mobile Ads Blog notes. "But our most significant findings centered on the clear consumer shift to smartphones. We partnered with Ipsos to conduct this research with a goal of gaining greater insight into consumer usage of mobile devices, the shift to smartphones and the emergence of tablets as a fourth screen."

I expected those four screens to be the TV, PC, smartphone, and now tablet. But if I'm reading this right, the study may be defining the four screens as portable PC, desktop PC, smartphone, and tablet.

The report says that usage in smartphones is up dramatically, with these devices now in the hands of 45 percent of consumers in the UK, 38 percent in the US and France, 23 percent in Germany and 17 percent in Japan. As important, perhaps, total mobile phone usage (i.e. feature phone and/or smart phone) now exceeds that of total PC (desktop and/or laptop) usage. And consumers are "clearly shifting from feature phones to smartphones," Google says. So it's only a matter of time before smart phone usage outpaces PC usage as well, I'd imagine.

(The smartphone/feature phone mix in the US is almost equal right now, so given the usage trends shown here I'd expect smart phone usage to surpass that of feature phones in this first half of 2012. But that's just the US; these figures vary from country to country.)

That said, consumers today are very comfortable using PCs in addition to their mobile devices. Google notes that fully 75 percent of smartphone owners continue to use their computer to access the Internet daily. And in the US at least, PC usage among smartphone users actually went up in the past year.

Tablet usage, meanwhile, is still relatively small though it's clearly on the way up. The US has the highest rate of tablet usage in the world, though it's at just 11 percent of all consumers. And tablet usage is dwarfed by PC usage. In the US, 73 percent of smartphone-toting consumers also use a laptop or other portable computer, and 57 percent use a desktop PC. Only 17 percent of this audience uses a tablet. Similar usage ratios are present in all of the other surveyed countries, but I'm curious to see how this changes over time.

In the summary of the study, Ipsos notes that the mobile Internet is today's main driver of growth in time spent online, and that smartphones have had a significant impact on Internet usage worldwide.