Apple's tablet, now expected to be unveiled next week, will likely sport a 7-in. screen in its first iteration, with a 10-in. model following to make it a credible productivity platform, an Apple hardware expert predicted today.

Aaron Vronko, the chief executive of Michigan-based Rapid Repair, a firm that specializes in iPhone and iPod service and repairs, laid out his educated bets on what Apple will reveal next Wednesday.

"I think there are two possibilities on the display, 7-in. and 10-in.," said Vronko, who based his estimates on reports from Asian component makers, his own experience with hardware technology and what would "actually make sense to do in a device." Vronko frequently does teardowns of Apple mobile devices to figure out what makes them tick and how much they probably cost to manufacture.

Because the display would be the most power-hungry of any tablet component, the size of the screen has broad implications. "I don't think it's plausible to make a device with a 10-in. LCD display," Vronko said, "because it would take nearly eight times as much power as the similar screen on the iPhone. A tablet would have to use either a smaller screen or a different screen technology."

Vronko's betting that Apple will not hang a notebook-sized battery on any tablet it crafts because of weight constraints and design limitations inherent with the slate concept. "Design is king at Apple," he said. "They won't want to produce anything much thicker than the current iPhone 3GS, around 16-17 millimeters or so. So a big battery is out."

A beefy laptop-like battery is also out, Vronko believes, because of weight limits. "The design I've specced out would come in under two pounds, around 28 ounces or so," he said.

With the battery limiting the size and weight of a tablet, Apple will have probably made a choice between a 7-in. OLED-based (organic light emitting diode) display and the power-sucking 10-in. LCD. Vronko cited an OLED screen's lower power consumption as a reason for tilting toward the former. An OLED screen would make it possible for Apple to construct a tablet with iPhone-esque battery life, such as 10 hours of video play or 20-30 hours for e-reading purposes.

Vronko argued that the 7-in. size was possible because enough would be available to meet Apple's bandied-about March shipping timetable. But that manufacturing volume would not allow a 10-in. OLED until later this year. "It's most likely an OLED screen, but not a 10-in. since it's doubtful any manufacturer would be capable of producing them in quantity," Vronko said. "They won't be until the third or fourth quarter."

The second, larger tablet would add not only a larger screen, but with that larger screen, the ability to conduct productivity chores, Vronko claimed. And that plays to both Apple's expected pricing and analysts' general belief that a Jobs-sanctioned tablet would have to have more than entertainment and e-reading applications to become an iPhone-like break-out device.

"A 10-in. tablet that offers productivity [applications] is one way Apple will be able to justify a $1,000 price," said Vronko. But for productivity tasks to be possible on the tablet, Apple will have to come up with a new way for users to enter data. "Hunt and peck is not going to work," Vronko argued, referring to the onscreen keyboard of the iPhone. "Two-handed touch, though, would be robust enough, and you could do two-handed [onscreen] typing on a 10-in. screen."

Find your next job with techworld jobs