NEW YORK (AP) _ Apple is expected to reveal a new iPad model on Wednesday, with a sharper screen and perhaps an option for faster wireless broadband. The upgrades are relatively minor, but the iPad is secure in its position as the king of tablets.

As usual, Apple has kept the features of the new device secret. No matter what they are, analysts expect the new iPad to be a success, riding on the popularity of the previous models, as well as pent-up demand from consumers who have been waiting for the new model.

The iPad 2 was a big step up from the original iPad, since Apple included a camera and reduced both the thickness and the weight of the device. But there isn't that much Apple can do to jazz up the iPad 3. Company watchers expect the new device to have the same basic size and weight as last year's model.

Nearly a year ago, the iPad 2 went on sale nine days after it was revealed. Apple watchers expect similar timing this year.

Some of the rumored new features include:

_ A sharper screen, similar to the ``Retina Display'' on the iPhone 4 and 4s. The rumored resolution is 2048 by 1536 pixels, which would make text look smoother and some high-resolution pictures look better. It won't make much of a difference for images on the Web, or video.

Some speculate that Apple will call the model the ``iPad HD,'' for ``high definition,'' rather than ``iPad 3.''

_ The new iPad could include Siri, the voice-activated ``assistant'' found on the iPhone 4S. Siri has gotten mixed reviews, but Apple has been touting the feature heavily in its advertising, and it would make sense to expand the availability of this high-profile feature.

_ Faster wireless capabilities. IPads are available with built-in modems for AT&T's and Verizon's third-generation, or ``3G'' cellular networks in the U.S. The iPad 3 could come in a version that offers faster ``4G'' or ``LTE'' networks. However, most iPads are used only on Wi-Fi, so an ``LTE'' chip wouldn't matter to most buyers.

In this respect, Apple is playing catch-up. Some competitors, such as Samsung and Motorola, already sell LTE-compatible tablets.

Since last fall, Sprint Nextel Corp. has sold the iPhone. But it doesn't sell the iPad. It's possible it could join AT&T and Verizon Wireless in selling the iPad 3.

_ A faster processor. This is pretty much a given, since every new iPhone or iPad has improved on the computing power of its predecessor. But few users complain about their iPads being slow, so this should not be a major selling point.

Sarah Rotman Epps, an analyst for Forrester Research, said hardware features aren't that important to tablet buyers.

``It's about the services _ what you can do with the device,'' she said in a blog post.

Apple's competitors have slowly come to realize this, but only after bringing out dozens of tablets with whiz-bang features like 3-D cameras. The competitor that's done the best is Amazon.com Inc. Its Kindle Fire tablet is cheaper than the iPad, but what really sets it apart is that it's tied into Amazon's book, movie and music stores, making it an easy route to entertainment, just like the iPad.

Still, the Kindle Fire has a long way to go. Epps estimates that Amazon sold 5.5 million Kindle Fires in the fourth quarter of last year. Meanwhile, Apple sold 15.4 million iPads, and has sold 55.3 million in total.

According to Canaccord Genuity, 63 percent of the tablets shipped last year were iPads. The only competitors with more than 5 percent market share were Amazon and Samsung Electronics Co.

The iPad launch comes as Apple has reached a rare milestone: last week, it was worth more than $500 billion. Only six other U.S. companies have been worth that much, and none have held that valuation for long. On Tuesday, Apple's stock had fallen, bringing its market value down to $493 billion, but analysts believe the company is worth closer to $550 billion.

One big unknown is whether Apple will keep the iPad 2 in production at a lower price, like it kept the iPhone 3GS after the launch of the iPhone 4. If so, the iPad 2 could carry a price tag that would make consumers think twice about buying a Kindle Fire.

Another big unknown is whether Apple will reveal its rumored foray into making TV sets. Some have speculated that the invite to the Apple event, which said ``We have something you really have to see,'' points in that direction.

Apple already sells and ``Apple TV,'' but that's a small box that attaches to a TV set to display movies and play music from iTunes.