Wonder why it took Samsung 2 1/2yrs to get this QD

Wonder why it took Samsung 2 1/2yrs to get this QD-display patent approved ?

Wavelength conversion member, backlight assembly, and display device including the same
Patent number: 9519161
Abstract: A wavelength conversion member, a backlight assembly, and a display device including the same are provided. In one aspect, there is provided a wavelength conversion member comprising a first substrate, a second substrate, a wavelength conversion layer, and a spacer. The second substrate is positioned on the first substrate. The wavelength conversion layer is interposed between the first substrate and the second substrate. The spacer is interposed between the first substrate and the second substrate to constantly keep a distance between the first substrate and the second substrate.
Type: Grant
Filed: June 4, 2014
Date of Patent: December 13, 2016
Assignee: SAMSUNG DISPLAY CO., LTD.
Inventors: Yeong Bae Lee, Seok Hyun Nam, Seung Hwan Baek, Sang Won Lee
http://patents.justia.com/inventor/seok-won-lee