Don’t be surprised if HP’s next TouchPad is a 7-inch tablet

Few tablet makers have dipped a toe in the 7-inch slate pool, but HP (s hpq) could be the next to test the waters, based on recent FCC documents found by Engadget and then inspected by an enthusiast site. A device named the TouchPad Go was tested by the FCC, which could just be a reference to a product with more mobility features such as an integrated 3G or 4G radio. But it’s hard to argue the Go isn’t a forthcoming 7-inch slate running webOS given two key pieces of evidence.

The FCC’s schematic diagram offers both clues, although one is obvious while the other isn’t. According to the PDF document, the model under test is named Opal. The original TouchPad, currently on sale now with a permanent $100 list price reduction, was codenamed the Topaz. So the device tested by the FCC isn’t a slightly different version of HP’s current tablet. This isn’t the first mention of the Opal name either; it appeared on a leaked HP device roadmap. The second data point is the size of the device’s required label, which is 2.067-inches by 1.161-inches. A forum member at the WebOSEnthusiast webOSroundup site extrapolated that size to the tablet drawn in the FCC documents and derived a device with a screen size of 7.32-inches.

HP planning to use webOS across a number of devices shouldn’t surprise. The company spent $1.2 billion to acquire Palm last year and has repeatedly said it would use webOS on phones, tablets, printers and even traditional PCs. HP bought a platform, and a few devices — such as the Palm Pre smartphone line — came with it. I think the company is betting that a one-size-fits-all approach isn’t the best strategy for smartphones, nor for tablets.

If the Opal is indeed a 7-inch tablet, it could help spur webOS device sales for those who don’t want to carry a larger slate. Although I’m likely in the minority here, I actually prefer a smaller tablet device for portability and ergonomic reasons. A 10-inch slate is great for media, web-surfing, email and more, but eventually, it gets heavy to hold. My experience with a 7-inch Samsung Galaxy Tab shows the device can easily be used anywhere, and for longer periods of time. Think of it as combining the portability of a smartphone with the usability and productivity of a larger slate. Heck, if HP added cellular voice capabilities to a 7-inch slate, I’d consider using it to replace a smartphone.