I am new to this patent protected deal and do not understand. I was looking to make some wind spinners like the ones described like this patent. Is this patent 4578291 still protected and valid. It is passed the 20 years from original posting... but does someone else own it or can anyone use this idea to make/sell this kind of thing ? There seems to be assignments and assignees what does this mean and do they still own the patent?
Jun 2, 1998 FP Expired due to failure to pay maintenance fee
Effective date: 19980325
It looks like the patent is public domain now. Now, that doesn't mean that another patent which incorporates some of the parts of patent 4578291 is not in force and still valid. Look up the REFERENCED BY section of 4578291 and see if you find something that matches what you're trying to build.