Omron B3K series

Omron B3K series
Manufacturer	Omron
Inventor	Yasuhiro Tanoue, Mamiko Naka, Kazuhira Izawa, Masayuki Shinohara
Product name	Logitech Romer-G,; Das Keyboard Gamma Zulu,; Creative Labs PRES
Introduced	2014
Switch type	Tactile, Linear
Sense method	Metal contact
Rated lifetime	70 - 100M
Actuation force	45 g
Pretravel	1.5 mm
Total travel	3.0, 3.2 or 3.5 mm
Switch mount	Plate mount
Patents	US20150043192 (2014); (also as CN104347295A, CN204011170U, EP2835808A1)

Omron B3K is a series are mechanical keyboard switches designed for backlighting. Switches have been released in branded variants as Romer-G for Logitech, Gamma Zulu for Das Keyboard and PRES for Creative Labs.

Description

B3K switches facilitate LED backlighting via a light pipe leading to a surface-mounted LED. The design is said to focus the light more evenly through the legends on the keycap and minimise light leakage^[1]. The patents describe various approaches to achieving the illumination, illustrated with light intensity plots.

The slider has four corner posts. Two of these each holds a sliding ramp, each holding one pair of metal contacts apart. The slider is supported by a large spring, which sits around the centre light guide. The switch provides redundant sensing in an SPST arrangement by using a pair of identical terminals, each bearing a stationary contact and a movable contact. The two lateral ends of each terminals are at 90° to each other, and collectively the terminals occupy all four sides within the switch, with the movable contact at one end of each terminal meeting the stationary contact at the opposite end of the other terminal.

Similar to Cherry MX, tactile variants have a bump on the sliding ramps. The patent depicts the tactile "pressing rib" design but does not explain the shape or mention tactility. The tactile variants have been compared in feel to the Cherry MX Brown switch by those who have tried it.^[2]^[3]

Variants

Romer-G

Logitech Romer-G exist in both tactile damped (B3K-T13L), tactile ((B3K-T13L2) and a linear variant (B3K-L13L). The top housing bears the Logitech "G" logo on two opposite sides, and the Omron logo on a third side. The bottom housing bears the part number.

The earliest variant was the tactile damped B3K-T13L, which can also be identified by having a blue housing whereas the others are black. Damping is on both the down-stroke and up-stroke, by having a pair of plastic prongs on the slider (called "elastic touch piece" in the patent). These collide with features of the base (downstroke) and lid (upstroke) to absorb impacts. Specifically, the prong hits a raised area in the base on the way down, and ridges in the lid on the way up. The patent describes the product as a "silent type switch having small operation sound and return sound". The key travel for the damped switches is rated at 3.0 mm, but has been measured to between 3.06 and 3.17 mm in reality.

The Romer-G variants with black top housing (B3K-T13L2, B3K-L13L) lack the damping prongs, and have instead more key travel: rated at 3.2 mm.

Logitech had applied for the "ROMER G" trademark on 23rd June 2014.^[4]

Das Keyboard Gamma-Zulu

The Das Keyboard Gamma-Zulu (B3K-T135M) are tactile and undamped with 3.5 mm key travel. The top housing is black, carrying the Omron logo and the Das Keyboard symbol on different sides.

They were manufactured by Omron for Das Keyboard (Metadot), starting with the Das Keyboard 5Q which was announced on a Kickstarter page in July 2016 with estimated delivery in Dec 2016.^[5] When announced, the estimated lifetime of the switch has also been upped to 100 million actuations, compared to 70 million for the first Romer-G.

Creative Labs PRES

Creative PRES switches (Perceive-React-Execute Switches) were introduced with the Sound BlasterX Vanguard K08 keyboard.

Observed variants

All variants have officially a pre-travel of 1.5 mm.

Brand Name	Part #	Colour (Top/Slider)	Type	Total Travel	Actuation force	Tactile force	Total force	Rated lifetime
Logitech Romer-G	B3K-T13L	Blue/Clear	Tactile Damped	3.0 mm	45 gf			70 M
	B3K-T13L2	Black/Clear	Tactile	3.2 mm		55 gf
	B3K-L13L	Black/Grey	Linear	3.2 mm
Das Keyboard Gamma-Zulu	B3K-T135M	Black/Clear	Tactile	3.5 mm	45 gf	55 gf	80 gf	100 M
Creative Labs PRES		Transp/Clear	Tactile	3.5 mm				70M

Gallery

Branding comparison: black has a revised Logitech logo

Blue Logitech Romer-G (B3K-T13L)

Top; the Logitech "G" logo is just about visible
Bottom, showing the base of the light guide
SMD LED chamber between the light guide and the PCB
Switch angled towards the light to catch a reflection of the branding
Demonstration of the SMD LED light guide
Omron part number (B3K-T13L) and what is presumably the batch number (217 5C4) on the side of the switch
Opened
Spring removed; the upstroke damping stop can be seen on the inside of the lid
Redundant contacts
Two identical terminals which achieve redundant sensing using two pairs of contacts, one movable and one stationary per terminal
Slider; the elastic touch piece and tactile ramp on one side can be seen
Opposite corner contact actuator ramps are different shapes
Disassembled, top views of components
Disassembled, bottom views of components