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Re: [ARSCLIST] Ampex & Sticky Shed Syndrome
From: Patent Tactics, George Brock-Nannestad
at some stage "patent assistance" was called for, but as usual in the
attorney world, we don't move unless someone foots the bill (James Lindner
likes to be paid, too!). Otherwise it is called "pro bono", and that is what
First of all, the Medeiros patent, US 5,236,790 assigned to Ampex, was indeed
published on 17 August 1993, and it is presently up for renewal: if USD 3,800
is not paid to the USPTO before 17 August 2005, the patent lapses. A
corresponding application in Europe was allowed to lapse in 1994, possibly
because one of the documents of prior art, the first Japanese text identified
on the front page of the US patent, was regarded as being a bar to patenting.
However, this patent relates to heating the tape by means of a heating
tonehead that the tape passes.
There is quite an uncommon Declaration in the "Other [prior art]
publications" section: the inventors declare that there is knowledge and use
outside the US of heat treatment. However, if that information cannot be
proven to have existed in printed form in the US at least one year before the
filing date 31 March 1989, it does not matter. I can't at present find the
material that was distributed by AGFA on their baking process, but it could
well be that information the declaration relates to.
The fundamental paper by Bertram and Cuddihy need not be cited in the
application, because at the bottom of p. 998 they state: "Since reversibility
of the hydrolysis process entails rejuvenation of hydrolyzed binders, it is
important to emphasize that rejuvenation times are in general impractically
long." And on p. 999: "As a practical matter, it has been shown that 1-3 days
storage in room environment followed by perhaps a tissue wipe is sufficient
to return the tape to a playable low error rate state." So this was the state
of the art, and the method defined in the patent claims constitute the
It is worth noting that the claims only protect the method used on recorded
tape, not on unrecorded tape. So it is entirely free to use the method to
rejuvenate unrecorded tape, and it need not be discarded before moving from
one location to another.
Anybody using the method commercially is infringing, if no licence agreement
has been concluded. However, private use is regarded as non-infringing.
Advertising a special oven commercially as being particularly good for tape
restoration would constitute contributory infringement, but obviously private
good advice would not.
Now for the next patent, but unfortunately my "good deed" time has just run