Omron B2R, B2H, B2G and B2A

Contents

• Overview
• Background
• Patents and utility models
• Series
  • B2R
  • B2G
  • B2H
  • B2A
• Keyboards
• Discontinuations
  • PRDN 373
  • PRDN 389
  • PRDN 524
  • PRDN 578
  • PRDN 649
  • PRDN 784
  • PRDN 1220
  • PRDN 1221

Overview

B2H, B2R and B2A were Omron’s high end keyboard and switch series. B2R was a reed switch series, while B2H and B2A switches used Hall sensors. The switches share patents and common design elements. Notably, the 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.

At present, very little has been discovered in the way of documentation on any of these series, and both the keyboards and switches are extremely rare. The only type ever observed in a keyboard is B2R, found normally in FANUC keyboards. All these series are long since discontinued.

B2H and B2R switches accept B2HK keycaps.

Background

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, because 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. (B2C does exist, but it was a foam pad capacitive type.)

Patents and utility models

Utility model JP S5048968 U (“Pushbutton switch”, filed 1973-08-31) depicts a three-terminal magnetically sensed low-profile keyboard switch. The illustrations are crude, but it bears a small resemblance to B2H-F7W.

Utility model JP S5152878 U (“Pushbutton switch”, filed 1974-10-17) depicts some kind of reed arrangement; again, the drawings are too simplistic to understand by themselves. The switch again bears a small resemblance to B2H-F7W.

Patent JP S53136680 A (“Keyboard Switch”, filed 1977-05-04) includes the magnetic click and tactile arrangement, depicted within a lower-profile reed switch.

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 patent depicts a Hall switch identical in shape to B2R (tall, plate-mounted), as well as the design of B2H-F7W (short, cube-shaped and PCB mount only).

Utility model JP S55138721 U (“Keyboard switch”, filed 1979-03-26 ) depicts B2R reed switches.

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.

Series

B2R

All B2R switch types discovered so far are reed switches, using a plastic carrier bearing a reed capsule. They 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.

Keyboards are currently known to use the M and ME subtypes. Subtype G is a larger, non-keyboard variety. There is also a variant of M (tentatively B2R-M-T with flat terminals that support threading wires through and solderless installation.

The following switch models are known:

B2R was discontinued at the end of March, 1993.

B2G

B2G is only known as a keyboard series.

B2H

B2H was a series of Hall effect keyboards and switches.

B2A

B2A is a Hall effect series. No such switches or keyboards have yet been observed. The following subseries are known:

The final digit of the model number seems to correspond with the final digit of the Hall IC.

See PRDN 784 below for specifications.

B2A was discontinued at the end of March, 1993.

Keyboards

B2H and B2R along with B2C keyboard model numbers begin with the same series name as the switches they use. There is also keyboard series B2G for which there are no known switches, and switch series B2A for which there are no known keyboard modesl. The “E” in keyboard model numbers might denote “encoded”, since the only types not to have the “E” are B2H-12-219 and B2H-12-336, which appear to be keypads, and these are often not encoded. The digit after the E would then be the number of encoded levels, from mono-mode E1 to quad-mode E4. This is however only speculation. One keyboard model has “Z” instead of “E”.

Keyboards with B2H and B2R switches are extremely rare, although B2R appeared in a number of FANUC consoles.

• B2R-84E2L-602, 84-key keyboard with B2R reed switches
• FANUC System P Model G (also B2R; keyboard model not known)

Discontinuations

Omron’s discontinuation notices provide most of the known data on these series. Notices covering only B2HK and B2H (and not also other series) are presented on their respective pages.

PRDN 373

All five discontinued models are dedicated products for specific customers.

PRDN 389

PRDN 524

PRDN 578

This document notes that (Matsushita’s) DN6837 Hall IC is discontinued, and thus B2A-□□7 subseries is terminating with it. (形B2A□□7シリーズに内蔵のホールIC形DN6837の生産中止にともない新しく形DN6852を内蔵しましま。) A new B2A subseries of B2A-□□2 was created in order to utilise the replacement Hall IC, DN6852. The dimensions and electrical characteristics remain unchanged. (これにともない形式を新たに形B2A-□□2シリーズとします。外形寸法・電気的特性は同ーです。)

PRDN 649

PRDN 784

PRDN 784 contains a number of specifications about B2A-□□6 and B2A-□□2.

PRDN 1220

PRDN 1221