I would like to know is patent "US6323569 B1" still valid? its end date?

2 Answers 2


If you look in http://portal.uspto.gov/external/portal/pair (enter the number without the "US" and "B1") as "Patented case" and the next fee payment window closes on 11/27/2013. The patent is valid. You will also be able to see that it had quite a stormy path to its acceptance which resulted in a certificate of correction.

If the maintenance fee is paid, the patent will expire on 11/3/2019, 20 years after the effective filing date.

  • This answer was close but should have also noted that if the fee payment was missed, then the effective date for expiration would be November 27, 2013.
    – Parker
    Jul 18, 2015 at 15:00

As of November 27, 2013, this patent had lapsed due to a Failure to Pay Maintenance Fee. As of January 14, 2014, US 6,323,569 is expired and is no longer enforceable, with an effective date of November 27, 2013.

Nov 3, 1999 AS  Assignment  

Dec 24, 2002    CC  Certificate of correction   

May 5, 2005 FPAY    Fee payment 
Year of fee payment: 4

Apr 29, 2009    FPAY    Fee payment 
Year of fee payment: 8

Jul 5, 2013 REMI    Maintenance fee reminder mailed 

Nov 27, 2013    LAPS    Lapse for failure to pay maintenance fees   

Jan 14, 2014    FP  Expired due to failure to pay maintenance fee   
Effective date: 20131127

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