IMS International was a US computer manufacturer. The initialism “IMS” stood for “Industrial Micro Systems”. Little is known about the organisation, but some details are on Herb Johnson’s Industrial Micro Systems/IMS International page.
Only one IMS keyboard model is presently known: the keyboard from the 5000 IS “desktop mainframe” system, which can be seen more clearly in eBay listing IMS International Mainframe Desktop 5000 IS CPM Model 5I8-2QH/60 …. The sole example is or was in MouseFan’s possession. This keyboard a moving-ferrite ferrite core implementation, marked as though it were manufactured by IMS in-house in the US. There is no model label on the keyboard, and presently no suggestion that it was patented. The copyright date on the PCB is 1982, while the encoder or controller chip is dated week 13 1983.
Indications are the keyboard OEM was in fact Elco Corporation’s Keytek division.