(in Japanese, Google translation to English Here)
The phenomenon of ghost images that are caused by the light reflection between the sensor surface and the surface of the rear glass element of the lens is illustrated as follows:-
Pentax' patent works against these reflections with "irregular" micro-lenses put onto the surface/top of the sensor:-
The patent is claimed to be more useful to help reducing ghosts for old film lenses when they are used on digital camera bodies.
Nevertheless, whilst the ghost image effect is reduced, will this measure affect also the final Image Quality? I really doubt it.. It is simply because an irregular sensor surface will probably create unwanted irregularities throughout the image frame, too, at the same time.