That is, the ratio of the front display part to the front area. General users think that the larger the screen ratio, the better it looks. That's why full screen is popular now.
For the Home button with the same function, the waist circle will be smaller than the size of the circle in the upper and lower width. In this way, you can try to make the chin of the mobile phone smaller and make the screen ratio bigger.
Compare the width of the circular home button on the chin and the circular home button on the waist.
With such a direct comparison, we can still see a little difference.
Of course, it is also possible that this round home button has applied for a patent. In order to avoid patent infringement, changing the appearance of the key is also a reason.