Prepare to feel very old. By December, U.S. stores will reportedly sell a TV set with four times the resolution of today's best HDTVs, according to Sony Corp. The set will measure 84 inches (213 centimeters) on the diagonal, making the screen area four times as large as the common 42-inch set.

The first high-definition TVs roughly quadrupled the resolution of the sets that came before them. Now, the industry is ready to do it again. 

Executives said Sony will reveal the price of the set next week.

There is, for now, apparently very little video content available that can take advantage of the higher resolution. Although, with some work and know-how, a computer connected to the set can display video in the ultra-HD  "4K" resolution. The set will also do its best to "upscale" TV, DVD and Blu-ray movies, so they look better.

Phil Molyneux, chief operating officer of Sony Electronics, said the situation was no different from the launch of the cassette tape, the CD or the DVD.

"We always get this question when we launch beautiful new technology: Where's the content?" Molyneux told journalists at an event in New York. "Did we bring the content to market? Yes, we did."

The exact resolution of the set is 3,840 by 2,160 pixels. It's known as "4K" because it has nearly 4,000 pixels on the horizontal edge. That compares with 1,920 by 1,080 pixels in "1080p" sets. More pixels allow TV makers to make bigger screens without compromising sharpness.

Sony makes digital projectors operating at 4K resolution for movie theaters.

The TV industry has been looking for a technology that will get consumers to upgrade their HDTV sets. Sales are slumping after an initial wave of upgrades from standard-definition sets, and 3-D sets attract only a small number of consumers.

Apple Inc. has slowly been quadrupling the resolution of its devices, starting with the iPhone 4 two years ago. This year, it released iPads and MacBooks with ultra-high-resolution screens.

Struggling Japanese TV makers are hoping to make a comeback with the next-generation 4K TVs that can turn a living room into a cinema-like experience. With their South Korean rivals dominating the global TV market, Sony Corp. and Toshiba Corp. said they plan to release 84-inch 4K TVs by year's end for Sony, and in April or later for Toshiba.

The new-generation TV's huge jump in technology is obviously its biggest selling point. But high prices and a lack of content carrying high-resolution images for the TV are huge hurdles for the Japanese TV manufacturers. Sony and Toshiba are currently displaying their new TVs at the IFA trade show in Berlin. South Korea's LG Electronics Inc. is also expected to introduce a 4K TV in North America and elsewhere in September.

Sony said its 4K TV will be priced at around 25,000 euros (or $31,000) in Europe, while Toshiba has yet to announce a price for its massive 84-incher. Both said their 4K TVs are capable of processing current HD images of digital broadcasting and Blu-ray Discs into higher resolution images.

Toshiba released the world's first 4K TV in December. Measuring 55 inches, it is priced at around 700,000 yen, more than three times that of a conventional TV of the same size. Toshiba said the product has sold about 1,000 units a month. "Sony's (4K) entry will galvanize the market," a Toshiba official said.

The new-generation TV needs four times the data of current HD TVs to fully take advantage of its capabilities. But currently the technology does not exist to broadcast 4K images or put 4K images onto discs.

"For the time being, we have no choice but to have people use the TV's image-processing function to view high-quality images," a Sony official said.

Despite the lack of content for 4K TVs, Sony and Toshiba decided on early releases of their 4K TVs because they said customers who are particular about image quality will want them.

Images on current HD TVs can appear grainy when viewed at a distance shorter than three times the height of the screen. But 4K TVs can halve that distance, enabling people to sit in front of an 84-inch TV at a distance of 1.5 meters.

Sony expects people who have small living rooms to buy the new large-screen TV, a company official said. Meanwhile, Japan Broadcasting Corp. (NHK) said it is developing technology to broadcast 8K images carrying four times the data of 4K. NHK plans to start test broadcasting 8K images in 2020.