I doubt you will find a patent, as you can build a DCC system by reading the standards and implementing the protocol. If there were patents involved, usually you would have to get a licence first before they would tell you anything, or allow you to use their trademarks.
The whole point of the NMRA DCC Standard was to eliminate the possiblity that someone would use patents or licencing as leverage over other manufacturers.
https://dccwiki.com/DCC_History
uspto.gov
It has been a while but there was a bit of a tussle over certain patents that Bob Grubba >Broadway Limited< and Mike Wolf, >MTH Trains< were squabbling over:
https://thedailyrecord.com/2009/10/19/model-train-maker-mikes-train-house-sues-longtime-rival/
There may be some insight over certain proprietary/intellectual design patents here.
https://www.courtlistener.com/opinion/2541745/mikes-train-house-inc-v-broadway-ltd-imports/
You could use some of the information garnered from those links to further Google patents related to the case.
Good Luck, Ed
I'm no expert but have enjoyed doing a bit of searching (and learning). Perhaps someone can direct you to a digital control patent, such as an early Lenz one, but that some of theirs may not be (NMRA standard compliant) "DCC". So it depends on precisely what you need:
1. The History & Protocols in the following link describes how the NMRA DCC standards were derived from the (German) Lenz systems of around 1989 vintage. It says that a Lenz/Marklin system was submitted to NMRA and the NMRA licensed the protocol from Lenz (and extended it). So any early Lenz digital control patents of early systems might be of interest, but are not NMRA Standard DCC. Not sure how to find a specific type.
https://en.wikipedia.org/wiki/Digital_Command_Control
2. If you are interested in more recent NMRA Standards compliant "DCC" systems, note that the NMRA Standards are not the Lenz protocol per se, but rather the Standards build upon that. You can read (scroll to Development / DCC Working Group / DCC Proposal / etc.) about how the submitted Lenz protocol served as a base for the NMRA Standards, which go beyond the Lenz protocol itself.
https://dccwiki.com/DCC_History#The_Early_Systems
So, not sure what you need exactly; e.g., an early Lenz digital system patent, the NMRA DCC Standards, or perhaps a patent of a current manufacturer's (even Lenz) NMRA Stabdards compliant "DCC" system, which may be patented re: their specific hardware / software implementing the NMRA Standards.
The NMRA Standards (and any related Recommended Practices) can be found here:
https://www.nmra.org/dcc-working-group
3. I randomly came across a patent application, which references other earlier patents. This one seems to be from about 2006, filed by 5 guys, related to (at the time?) Lionel LLC. Perhaps the patent application relates to some obscure design specifics of a particular application, under the umbrella of the NMRA Standards. It may serve as your example, perhaps, if you just need a DCC related patent.
https://patents.google.com/patent/US7656110
4. Perhaps someone more familiar with the history can clarify. Did not Lenz market a system in North America until recently? If a NMRA compliant system (vs. a proprietary system lacking some NMRA technology specifics), that could be the ideal case if a DCC "Patent" is needed. EDIT: I note in the following that the later Lenz "Digital Plus" product line is (was, if no longer available) a NRMA DCC complaint set of equipment:
https://dccwiki.com/Manufacturer:Lenz#Lenz_Digital_Plus_Product_Line
http://www.dcctrain.com/shop/category.aspx?catid=25
I hope the above is not confusing. I'm a 2012 NCE DCC learner, so I missed the evolution of DCC in the 1990's. Please let us know if we have helped with what you need.
5. EDIT (AGAIN):
Maybe a "bingo". Used the following google patent search site, searching for "all the words": DCC railroad Lenz
https://books.google.com/advanced_patent_search
The 1st thing on the search list is this Lenz patent application. Look at the "events" list and you will see the patent was granted 11/21/2006. Not sure what this "invention" allows a patent under what I assume is the NMRA standard "DCC" umbrella, as opposed to a non-NMRA compliant, proprietary Lenz other type digital system. I did not read much, so please peruse to ensure it relates to the NMRA DCC standard, if that is what you need.
https://patents.google.com/patent/US7137600?oq=dcc+railroad+lenz
That's all...the Penn State game is starting.
Paul
Modeling HO with a transition era UP bent
this is from DCCWiki (click link)
Since the NMRA cannot endorse or standardize a proprietary product, a potential standard cannot contain copyrighted, proprietary or patented components, Lenz GmbH agreed to the NMRA request to release all their rights to the technology for sale outside of Germany. This would allow other companies to enter the DCC market freely, without the requirement of seeking a licence from a competitor. It also allowed everyone to be on the same footing with respect to features. The DCC WG further improved the DCC Standards so that no infringement would take place if the product were to be sold inside Germany.
greg - Philadelphia & Reading / Reading
I am working on a paper as a class assignment. Does anyone have a link to the DCC patent they can share with me? I need to include it as part of my assignment. Thank you.