The biggest exhibition of consumer electronics, CES 2014 in Las Vegas, has just finished, and it gave everyone a chance to look at the innovations coming our way this year. But here’s the thing: The big TV manufacturers are scared that people are not going to buy new sets because they don’t have a reason to upgrade.

Some of the TVs on display this year could arguably be described as the best ever produced. Innovations designed to capture the imagination of consumers include:

“4K Ultra HD” resolutions

120 inch screens (that’s bigger than some of my walls!)

Curved screens

Voice and gesture control

OLED screen technology

Internet video streaming integration

However, this trend of adding new features has accelerated over the past few years, because its becoming harder and harder to convince people to buy a new TV. Now that the majority of people have an HDTV, whether its 32 – 42 inches, most people find that their current set is sufficient for their needs. Over all, in the year that ended in November, TV makers sold $15.5 billion worth of sets in the United States in 2013, down about 4 percent from the same period in 2012, according to NPD. Worldwide, manufacturers shipped 155.4 million television sets in the first three quarters of 2013, down about 3.6 percent from the same period in 2012, according to NPD DisplaySearch.

In fact, there is a limit to how much resolution the human eye is able to recognise depending on how big a screen is and how far away it is. For most appartments that cannot fit a 50+ inch screen, you wouldn’t actually be able to tell the difference between an HDTV and a new 4K TV. The chart below shows the preferable screen resolutions and sizes.