It's a blurry line between ideas and implementations. For example, Edison wouldn't have been able to patent the "idea" of a bulb that produces light, but he was able to patent the "implementation" of using a metal filament in an evacuated bulb, etc. But that's just an idea too, and you could say that the specific implementation would involve the exact size of the filament and metal composition, etc -- but that's more specific than his patent.
My point being: The term implementation in software tends to mean something much more specific than a patent is intended to protect. In software an implementation typically refers to the specific code. The lightbulb analogy would be the specific shape of the glass, the specific composition of the filament, the size, the way it's mounted, etc. Patents are *broader* than that, but not so broad that you can just cover some arbitrary idea like "an electronic device that produces light".