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Fujitsu FKB4700 series

Contents

Overview

Fujitsu’s FKB4700, FKB4720, FKB4725, FKB4726 and FKB4730 series keyboards make use of their clicky rubber dome switch system. These switches gained the nickname “Peerless” at some stage in the past, which was a misinterpretation of marketing term used by Fujitsu in the 1990s for these keyboards once they became the highest-quality consumer keyboard in their product range.

There are a number of sub-series:

Series Description
FKB4700 Original series
FKB4720 Difference compared to FKB4700 not known
FKB4725 As FKB4720 but with Windows keys
FKB4726 Difference compared to FKB4726 not known; possibly the PS/2 versions
FKB4730 Custom types

Switch

The switch type in these keyboards comprises a coil spring inside a plastic tube that sits over a rubber dome. This arrangement provides a very soft click feedback that is far more suitable for modern office enviroments than traditional clicky keyboards. There appear to be two generations of these switches.

In-key LEDs are provided by pressure connections between the LEDs and the membrane sheets. Some kind of conductive carbon pads carry current from the membranes into the LEDs.

Similar switch types

At least two other manufacturers designed similar switches:

Company Patent Title Filed Published Notes
Focus Electronic Co Ltd US 5442152 A Computer key switch 1994-09-28 1995-08-15 The click sound is attributed to “barbs” within the spring tube hitting some part of the tube within the slider in which it fits.
Silitek Corp US 5938009 A Key switch for a keyboard 1998-08-24 1999-08-17 The sudden extension of the coil spring is said to generate the click sound.

“Peerless”

The term “Peerless” itself is applied to model FKB4725-651 (N860-4725-T651), which is captioned “Peerless Windows 95 Keyboard”. FKB4725 Series is a Windows 95 version of FKB4720 Series; the earlier model FKB4725-601 comes in boxes marked “Model No. FKB4700 Series”/“FKB4720 Series” and these boxes are fairly plain and make no mention of “Peerless”. The FKB4725-651 box (and possibly those of non-US layout models) advertise the keyboard’s characteristics, including the “Crisp tactile feedback” and “Click-type full-travel keyswitch”.

“Peerless” appears to be a marketing term arising from these keyboards becoming the highest quality consumer and office keyboard available from Fujitsu. The datasheets at the time gave the following grades:

Grade Model
Peerless FKB4725-651
Value FKB8725-651
ValuePlus FKB8735-801R, with integrated “ErgoTrac” pointing device

Specifications

The specifications in all datasheets for FBK4700, FKB4725 and FKB7426 Series are as follows:

Travel 3.8±0.5 mm
Operating force 55±25 gf
Tactile response 20 gf
Lifetime 30 million

The force curve is given as follows:

Although the weightings do not match (possibly from rubber stiffening), broadly the official force curve of FKB4726 Series matches up with SPARC’s measurements of N860-4720-T207.

Models

Standard

Standard models include:

Model Keys Layout Connector Logo PC99 RoHS Reference
FKB4700-101 101 US AT None No klikkyklik.wordpress.com
FKB4700-152 102 UK AT None No KCref
FKB4700-601 101 US AT with PS/2 adapter Fujitsu No WorthPoint
FKB4725-101 104 US AT None No Datasheet
FKB4725-201 104 US PS/2 None No Datasheet
FKB4725-601 104 US AT? Fujitsu No Datasheet
FKB4725-651 104 US AT with PS/2 adapter Fujitsu Datasheet
FKB4726-601 104 US PS/2 None Yes No Datasheets
FKB4726-601/20 Yes
FKB4726-651 Fujitsu No
FKB4726-651/20 Yes
FKB4726-602 105 UK None No
FKB4726-603 German
FKB4726-604 French
FKB4726-605 Italian
FKB4726-606 Spanish
FKB4726-607 Swedish
FKB4726-608 Swiss

FKB4725-651

The FKB4725-651 box describes the product as “The premium Windows 95 keyboard… when you want the best” and cites the following characteristics:

Custom

FKB4700 keyboards were also made as fully-custom assemblies for other computer system manufacturers. These are fairly rare. Known models include:

Custom model Fujitsu part Switch type Reference
Data General keyboard N860-4735-T301 Type 1 eBay
ICL 16022/046 Type 1 Lost

Uncertain

Model or part number Notes Reference
N860-4709-T101 The FCC ID label says “MODEL FKB4700 SERIES” as normal, but there is no model number on the paper label. It looks to be a normal FKB4700 with a DIN-5 connector. WorthPoint

Documentation

See also