Q: Is patent 6782558 expired, and can I use the design?

A: Patent 6782558 appears to have been issued on August 31, 2004. While my search did not reveal the exact filing date, I can analyze the expiration status based on patent law principles.

For patents issued from applications filed after June 8, 1995, the term is 20 years from the earliest U.S. filing date of the application. As the USPTO states, "for applications filed after June 7, 1995 that the term of a patent begins on the date that the patent issues and ends on the date that is twenty years from the date on which the application was filed in the U.S."

If we assume this patent was filed after June 8, 1995, it would have expired 20 years from its filing date, which would likely be sometime in 2024 (if filed in 2004) or earlier (if filed before 2004). However, the actual expiration date depends on several factors.

The expiration status also depends on whether maintenance fees have been paid. Maintenance fees are due at 3.5, 7.5, and 11.5 years from the patent grant date. If these fees were not paid, the patent would have expired prematurely.

To determine with complete accuracy whether this patent is still in force, you would need to check the USPTO's Public PAIR system to verify if all maintenance fees have been paid and if there were any patent term adjustments or extensions.

Regarding using the design associated with the patent, it's important to note that once a patent expires, the invention enters the public domain and can generally be used without infringing the patent. However, this does not mean other aspects of the design might not be protected by other intellectual property rights.

You may wish to consult with a patent attorney who can conduct a comprehensive review of this specific patent's status and advise you on potential legal implications before proceeding with using the design.