Originally posted by Asahiflex Maybe it mechanically replaces the ground glass screen with a LCD screen? Although to me that seems to be a little stupid and overengineered...
The patent describes not a replacement for the ground glass, but a supplement (a thin EL layer). The point is to simplify any live-view/overlay mechanism for the viewfinder, where you'd normally have to switch from the viewfinder to the LCD screen. So it's not necessarily over-engineered or stupid, but simply solving a problem (that is, not take your eye away from the finder).
From the patent in question:
Quote: ... an optical image of an object formed on the focusing screen and a live digital image of the same object displayed by the EL display can be selectively viewed through the viewfinder. According to this structure... [it] facilitates the image switching operation and prevents the structure of the camera becoming complicated.
I can see how this would be a simpler approach to handle overlays and live-view compared to the Sony translucent mirror tech in their recent and current SLT models or the Fuji hybrid viewfinder in the XPro1/X100/X100s models.
If the hump is related to this patent, I can see how this would be a different approach that Pentax seems to be proud of in its cryptic interviews.