Paper Display mode is a new feature of Yoga series notebook computers. When enabled it dims the display slightly and adjusts the shade of the white background to become warmer. This feature is intended to simulate the characteristics of paper, making it easier on the eyes to read books, PDFs and similar material.
You can toggle Paper Display mode on Yoga models that support this feature by pressing Fn+Esc. An on-screen message temporarily confirms the status of this mode.