You are correct that if there are stacked filter sheets that always look red, green, and blue, then no light can be transmitted! So, obviously, the drawing and explanation must be confused and misleading. You can find an example of the kind of LCD shutters I described here:
http://www.colorlink.com/tecpage/tecpage.html
different possible arrangements:
http://www.colorlink.com/tecpage/pdf...olorswitch.pdf
complementary color version I described:
http://www.colorlink.com/tecpage/pdf...0colorquad.pdf
more:
http://www.colorlink.com/tecpage/pdfs/pw97.pdf
what I described:
http://www.colorlink.com/tecpage/pdfs/pw96.pdf