Hi Jdaasoc; The patent you referenced is in the process of being invalidated by the judge in the Infineon case. The reason is prior art. The prior art is SDRAM itself. Note that that patent was only granted in 1999, long after SDRAM was invented.
The patent tries to avoid prior art by using an effective filing date of 1990. The problem with that is that the filing of 1990 did not include the claim included in the 1999 patent. Consequently, the later patent does not get the advantage of the earlier filing date. Because of the lack of that advantage, SDRAM itself is prior art.
Rambus' 1990 patent is hard to find. The 1992 patent is all over the web (and I posted links to it on this thread) and it is very similar to the 1990 filing, which conclusion you will come to if you read the Markman briefs by Rambus and Infineon. The problem for Rambus is that the 1992 filing only includes inventions that include a Rambus style multiplexed address/control/data bus, as well as a big pile of other Rambus specific stuff. Later patents can't claim more patent "property" than was claimed in the original filing (or to the extent that they do claim more property, they lose the advantage against prior art, of the earlier filing date).
I hope this explains why it is pointless for me to look for prior art to that patent. At the time the patent was filed, November 20, 1998, the invention was already well known.
I'll try repeating this argument, maybe I've been obtuse. Since the 1998 patent (the one you link to) covers more patent "territory" than the 1992 patent (which as I have shown above specifically excludes SDRAM), it may not receive the advantage of the earlier filing date, even though it is a continuation of the 1992 patent. Consequently, I only have to find art prior to 1998, not 1990. But SDRAM was already publicly specified long before then. Therefore, SDRAM itself is prior art to the patent. Consequently, the legal ruling will be that the patent is infringed, but is invalid.
The reason for this rule (that you can't expand patents without losing the advantage of the earlier filing date as far as prior art goes) is obvious. Patents in addition to telling people what you invented, must also inform them of exactly what you didn't invent. In other words, patent owners must so completely describe their invention that the public can be sure of when they are infringing the patent and when they are not. You can sometimes expand patents you have already filed, but you cannot expand the territory they stake out, unless that territory is still unused. Since SDRAM was invented in between when Rambus came up with their original patent and when Rambus came up with the extension that covers SDRAM, that means that SDRAM got there first, and SDRAM itself is prior art to the patent. If Rambus had filed the continuation for the above patent in 1992 instead of 1998, SDRAM would not be prior art to it, and the whole Markman thing would have gone differently.
One more time I'll try and explain this principle. Patents are like beach towels. An inventor shows up at the beach, and puts out his towels. Those towels show everybody exactly where the inventor's patent property is, and if they walk on it, they have to give the inventor money. Now if the inventor suddenly realizes that he could have spread his towels wider. He can do this, but he has to do it before someone else sits in that spot. You can't put your beach towel on top of where someone else is already sunning themselves. Even if you could have put your beach towel there before they arrived, by the time they're sitting there, it's too late. You have to specify the full extent of your patent coverage up front, at the time of filing (or within 2 years, if my memory serves me correct).
What happened with Rambus was that Rambus put out rather narrow beach towels, and SDRAM came by and sat down next to Rambus. Then Rambus got the patent office to extend its beach towel over the place where SDRAM was already sitting. But the court gives priority to those who were first, and that is SDRAM, not Rambus' patent. The Markman briefing was a case of the court saying "No!", "Down!", Bad dog!" to Rambus for doing this.
Rambus is an IP company and should have known better.
-- Carl |
