Here's an image from their d-pad patent:
The thing about patents is they are supposed to be precise. While modern patents can be intentionally vague, in order to seek financial relief from anyone who comes anywhere near a similar concept, it seems that Nintendo was very specific about the description and functionality of their d-pad, leaving the door open for Sega and other companies to make functionally similar but non-infringing controllers.
Nintendo's patent is very specific about the cross-shaped mechanism:
Quote by patent:The character moving switch (8) is formed in the shape of a cross
Is this the loophole used by other companies when they released their own controllers? It seems obvious on some level that Sega, NEC, 3DO and everyone else went with round d-pads for some reason, but was it the patent or did they have other reasons? It's possible, though I think unlikely, that they were trying to be different for the sake of it, or genuinely thought they had a better plan (yeah, right).
Most other d-pads were less player-friendly: Sega's Master System-era pads were terrible, with large square d-pads. They only started to get it right with their 6-button MegaDrive/Genesis pads. NEC had a winner with their round TurboGrafx/PC Engine pad, 3DO totally failed with theirs, but they all seemed to wish they had cross-shaped pads as, square or circular, they all had cross-shaped raised sections to aid the player.
I have another question: Nintendo's patent didn't expire until 2005, according to Wikipedia, which means that the Dreamcast - released in 1999, should have infringed with its cross-shaped d-pad. How did they get away with it, another loophole? It doesn't seem plausible that Nintendo would license the idea to a competitor, and certainly not at rates Sega could afford at the time.
So Nintendo invents the cross d-pad, and everyone else is stuck using discs. Sony, of course, broke their cross into four pieces, side-stepping very nicely the Nintendo patent, and some third parties - notably Hori - either licensed the Nintendo IP or simply operated with some level of impunity or disregard for the patent.
The patent listed several other components as well, though these were effectively ignored, and included in every other pad. Specifically the fulcrum/lever mechanism of the d-pad, the springy rubber pads underneat the d-pad, and the way they contact the electrodes on the PCB. Since every other pad included every other part of this patent but the shape of the d-pad, I have to wonder why. I have three theories:
- a trial reduced the unique component to the cross alone,
- nintendo licensed everything but the cross to prevent going to trial while retaining some unique elements, or
- a gentlemen's agreement to the same end
I doubt I'll ever know the truth for sure.