Fujitsu FKB4700 Series
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:
|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|
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:
|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.|
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: FKB4725 Series was classified as “High” on the Fujitsu Takamisawa website in 1998. The datasheets at the time gave the following grades:
|ValuePlus||FKB8735-801R, with integrated “ErgoTrac” pointing device|
The specifications in all datasheets for FBK4700, FKB4725 and FKB7426 Series are as follows:
|Operating force||55±25 gf|
|Tactile response||20 gf|
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.
Standard models include:
|FKB4700-601||101||US||AT with PS/2 adapter||Fujitsu||No||WorthPoint|
|FKB4725-651||104||US||AT with PS/2 adapter||Fujitsu||Datasheet|
The FKB4725-651 box describes the product as “The premium Windows 95 keyboard… when you want the best” and cites the following characteristics:
- LEDs in keycaps
- 3 New keys for Windows 95
- Crisp tactile feedback
- Curved steel keyswitch panel
- Click-type full-travel keyswitch
- Full-size layout
- PS/2 adapter included
- Novell Netware YES approved
- SCO approved
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|
|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|
All material was scanned by Bitsavers unless otherwise noted.
- FKB 4700 Series and FKB 4800 Series advertisement, Electronic Engineers Master Catalog 1991–92 Volume B
- Fujitsu Peerless Keyboard FKB4725-651 datasheet (1998; from fujitsufta.com)