In terms of when Paiste patented the flat ride in the USA:
Paiste Flat Ride: United States Patent 3,546,994 Issue Date: December 15, 1970 filed Jan 22, 1969
That leaves a bit of a timing window between the SpaceSound and the patent being issued for a flat ride (if it was advertised in 1964). From my memory (I'm no patent attorney) you create a problem if you advertise and begin to sell something before you submit the patent.
During the period between Jan 22, 1969 and the issue date December 15, 1970 Paiste started printing "Pat. Pending" in ink on the bottom of the flat rides. I've got one and I've seen several others. Then over time more countries were listed on the underside as Patented. I've recorded some flat rides with: switzerland, canada, usa, and some with longer lists.
In my sales database I've recorded two spacesound sales, on 18" and one 20".
fo602 20 flat spacesound 2300 good preserial ebay 11-Nov-08 $300.00 BIN logos faded
fo602 18 flat spacesound good preserial ebay australia 11-Mar-13 $245.00 BIN logos faint > cymbalista
I didn't record that they had any ink underneath showing anything about patents. Since they are so rare I would have if I knew about it at the time.