The history of Cherry MX is not clear. It seems that MX was introduced over a year after the patent was filed.
The following occurrences have been discovered to date (not counting more recent switch models):
|1982-08-06||Date of patent application by Cherry Mikroschalter for MX White||German patent 3229465|
|1982-11-05||Date of early (if not the original) MX part number schema (Nummern-System Tastenmodul) covering MX Black, Linear Grey, Lock, White and Click Grey (last revised 1983-09-07)||Cherry drawing TS 00006|
|1983-01-25||Date of single-unit 8 mm keycap drawing (last revised 1987-10-21)||Cherry drawing 1P■11-NNNG3|
|1983-07-12||Filing date of US patent for MX White by Cherry Electrical Products in the US||US patent 4467160|
|1983-10||Introduction of Cherry MX in Japan; according to the former Hirose Electric website, “Started sales of MX series, the Low Profile Key Switch.”||hirose-st.co.jp (Wayback Machine)|
|1983-11-07||Date that Cherry MX was introduced, according to a suspicious image from an unspecified brochure||Deskthority topic|
|1985-07-28||Handwritten date on a German datasheet listing MX Black, Linear Grey, White and Click Grey, but curiously not MX Lock||Cherry MX datasheet|
|1987-04-24||Application date for MX Clear patent from Cherry Mikroschalter||German patent 3713775|
|1988-03-31||Date of a revised MX part number schema which added MX Clear, Tactile Grey, Blue and Green (last revised 1988-08-10)||Cherry drawing TS 00006-2|
|2009||Hirose Cherry MX no longer advertised for sale||Correspondence with Hirose|
|2014||Hirose Cherry MX discontinued||Correspondence with Hirose|
The idea that the return spring descends into the central post, as seen in Lethal Squirrel’s animations, is a myth. The return spring is exactly the same width as the central post; the post only provides additional movement capacity for the slider.