The recent threads about patents and the "multigrade" thread got me thinking. How about a thread about patents. You just list the patent number, it's title or a short description, and maybe a couple words about why you found this patent interesting. And if possible, a link to it to make it easy to access.
Most important, let's not get side-tracked with discussions about the content of the patent or it's usefulness, let's just build up a repository of patents that others can use to research and learn about photography.
So no words - at least in the sense of a discussion. Just a simple listing of interesting patents.
So here's the ones Ryuji listed in the multigrade thread, "Check out U.S. Patents 2,202,026 (Renwick), 2,280,300 (Potter et al), and, for your reference for the conceptual father of this technology, British Patent 15,054 of 1912 (Fischer)."
Photography patents are very interesting, sometimes what appears to have been left out - but you assume happens can make a huge difference.
I'll give you an example; Make a fairly standard B&W emulsion, spray it on a surface, expose a neg to the emulsion via an enlarger, process normally. Is that new, no say the Patent Office
But the process was granted a patent . . . . . Why ? Because the gelatin emulsion was not dried, it was only allowed to set, so used like a "Wet Plate" emulsion.
I agree with Ian, and I can add that often your assumptions are wrong due to much of the patent material being on new ground. OTOH, the patent can be misleading by what is left out. It will work, but that is not the way it is done in manufacturing and it may take someone years to figure that out. After all, a patent need not disclose trade secrets.
PE
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It's interesting reading older Patents, they are full of irrelevance. I read a lot a month or so ago and it was only hindsight that allowed me to realise the deliberate false tracks.
I have almost 2 boxes full of patents here at home that were sent to me about items of interest to my R&D work. Not one of them helped. Our own internal work was much more significant. I can mention the patents on organic bleaching agents for sliver and the Cupric salt bleaches. Neither worked at all as advertized and a whole group of us failed to get them to work beyond simple examples. In fact, I've mentioed BP 911,412 (IIRC) that seemed to have patented just about every Ferric EDTA blix in existance, but in fact was wide open and didn't work in some of the examples due to formation of insoluable Ferric and Ferrous salts in the coating, just as the Copper did from the Copper blix patents. The list is long and sad.
Of course, emulsion work is even more obfuscating.
I'm a bit reluctant to read patents at the moment. The last patents I read were rather recent ones seemingly on chromogenic films. I got NO idea beyond that what the authors were talking about, as if they had been written in a alien language...
Yes, I know the idea behind some patents applications and that keeps the fun off it.
Though, if you can present some really intriguing ones...
So here's the ones Ryuji listed in the multigrade thread, "Check out U.S. Patents 2,202,026 (Renwick), 2,280,300 (Potter et al), and, for your reference for the conceptual father of this technology, British Patent 15,054 of 1912 (Fischer)."
You might note that the Renwick patent uses 2 different emulsions of ordinary type, one pure Chloride and the other ChloroBromide.
In addition, he mentions use of a dye that is tightly adsorbed to the grain.
So, you see that you can mix halides and you do use strong dyes.
The second patent to Potter et. al. describes the use of sensitizing dyes that decrease contrast. It is well known that many dyes both spectrally sensitize and antifog (reducing contrast) at the same time.
Both of these patents have been used in one incarnation or another.
Photo Patents - No Words 
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