I guess you're referring to the beam splitting prism with three CCDs?
That was the standard method for electronic cameras for a long, long time. From the first color TV camera in 1954, they used that scheme. Three Vidicons, each a B&W with a color filter (R,G,B) in front, behind a light splitting prism.
Later on the Vidicon tubes were replaced with solid state CCDs, of course.
That idea pretty much followed the motion picture film scheme that used the same basic principal, known as Technicolor.
The idea actually works better than Bayer's idea of using colored filters over a single sensor in a pattern, but it costs a lot more (obviously).
Many of the commercial HD video cameras still use that scheme today. I'm talking about those big ones you see at professional sports games, not the smaller shoulder mounted ones. The TV producers love to point those things at each other when nothing else is happening and they're unable to go to a commercial.
There was a similar scheme from Kodak for product-shooting studio DSLR work, where they stuck a box containing three color filters in front of the lens and one took three shots and the wheel rotated automatically between shots. That was for the DCS 4xx series, but one rarely sees the color wheel attachment any longer. I don't think they sold many.
As far as the RD175 goes, I think that was the only DSLR that made use of the 3 CCD scheme.