Omron B2C, B2H and B2R
B2C, B2H and B2R form a family of Omron keyboard switch series that share patents and common design elements. These switches support centre illumination using a novel method of replacing the return spring with a pair of side-by-side internal springs that carry the LED current. Unlike Alps and Cherry designs where the LED is supported on external springs, here the LED springs are internal and support the plunger. It appears that all the switches offer both upstroke and downstroke damping.
This family uses both Hall sensors and reed capsules.
Some time back in 2016, I came across an unidentifiable Omron switch on AliExpress. The sole photograph was fairly small, and the only identifying mark was the word “OMRON” along the top. At $145 for a lot of ten used switches, they were ridiculously overpriced and I declined to buy them. However, I was extremely intrigued by this unknown Omron switch, and eventually I could not resist temptation any longer, and purchased a lot of ten.
I found out what they were before I received them, as after they were desoldered and shipped domestically within China, another AliExpress seller posted extra photos, where the series name moulded into the switch—B2R—was readable, along with a letter M printed on the side that implied model or part B2R-M. From this I found B2R-G1, a non-keyboard reed switch, and guessed (correctly) that B2R-M was also a reed switch.
Fast forward to June 2018: a patent search on Espacenet for Omron turned up a couple of interesting patents for this family (see under patents below). The patents covered Hall and reed sensing and centre illumination. Since the tall shell is used with both Hall sensors and reed capsules, one could argue that the “R” in “B2R” stands for “reed”. This would suggest that the Hall effect switches would be either B2H (for “Hall”) or B2C (for “contactless”). An Internet search immediately turned up such a switch, for sale over at Yahoo! Japan: B2H-F7W. This switch was in fact the lower-profile, PCB mount–only design also featured in the patents. Blaise Cannon proxied some for me, and I also directed Jacob Alexander to them, and he acquired some and measured one.
Patent JP S57136719 A (“Method of Producing Illumination Keyboard Switch”, filed in 1979 or 1982) covers Omron’s centre illumination system using two parallel return springs to support the plunger and supply power to the LED. The Hall IC version is depicted, but I don’t know if that is mentioned. The patent does detail an extra part that appears to be used (based on a translation of a laborious correction of a lousy OCR attempt at a couple of paragraphs) for both alternate action and tactility. The latter may explain what the triangular slot is in the plunger of some B2R switches, but a proper translation is required to be able to determine this.
Patent JP S55105916 A (“Contactless Keyboard Switch”, filed 1979-02-06) appears to cover the Hall sensing option; again, I cannot translate it, and the drawings are unclear, but this time the Hall sensor is marked. This latter patent introduced a second size and shape of switch: a cuboid shell designed only for PCB mounting.
Patent JP S53136680 A (“Keyboard Switch”, filed 1977-05-04) includes the magnetic click and tactile arrangement, depicted within a lower-profile reed switch.
All B2R types discovered so far are reed switches, using a plastic carrier bearing a reed capsule. The following codes have been found on B2R switches; the series names moulded into the switch have been joined with the part-specific characters, but these may not be complete or actual model or part numbers:
- B2R-M (momentary)
- B2R-M1 (momentary)
- B2R-ME (momentary, LED illuminated)
- B2R-ME1 (momentary, LED illuminated)
- B2R-G1 (momentary; tall, non-keyboard)
B2R switches found so far are all fairly tall, with a shell around 15.5 mm tall not including standoffs. The shell and plunger support both tactility and alternate action, but it remains unclear quite how this works, as the patent drawings differ from production B2R switches.
Only one B2H switch has been found to date:
This is a Hall effect switch, smaller at only 12 mm tall. There is presently no evidence to indicate whether these smaller switches support either tactility or alternate action.
No B2C switches have yet to be observed; the existence of the series is derived from discontinued part numbers.
The part numbers of discontinued types are much more complex than the model numbers seen, and the series appears to be quite extensive.
|Date of notice:||1987-12-01|
|Date of discontinuation:||1988-02-29|