Target doesn't seem to be some Patent holding company

Han Nee invented the unique material and process in the 90's , doesn't really matter when he filed the patent

Apparently others have been paying for the material or licencing it under non-disclosure agreement

problem with a patent, is that you do need to disclose the invention, once you've done that, especially in the case of a chemical process, competitors can often figure out how to change your process enough to file a new patent, and you're screwwed because you filed

If Sony is essentially duplicating Target's formula's and processes, it's likely due to intentional back engineering or someone in the industry violating a NDA

I can certainly see the problem with software patents, but an inventor of something so useful and profitable by all as a cheaper way to make DVDs, certainly should be rewarded a few pennies per unit for several years