As we’ve said before, wearable computing is coming. We know it’s on Google’s mind — last month the company showed off its Project Glass eyewear. And we’ve seen evidence that Apple’s interested as well.

The Cupertino company filed for another wearable computing patent this week. The application covers an invention that, as you can see in the above image, has to do with a head-mounted digital display…

The New York Times points to a recently published patent application, discovered by PatentlyApple. The document is titled “Display Resolution Increase with Mechanical Actuation,” and it describes a method for increasing the pixel density of a head-mounted digital display.

Before we jump to the conclusion that Apple is readying a Project Glass competitor, there are a few things worth noting. The first is that this is not a design patent, so Apple is not required to depict what the actual device looks like. And the second, is that the application does say that this technology can be used for other types of devices, such as television sets, or computer monitors.

But if we were to combine this invention with some of the other ones we’ve seen over the years, it certainly looks like Apple is interested in making some sort of wearable computing device. Earlier this month, the company was granted a patent called “Peripheral treatment for head-mounted displays.” And a few years ago, a similar filing surfaced that described a goggle-like contraption.

The question is, what is it?