Editing Fujitsu Leaf Spring

{{Infobox dswitch
| name              = Fujitsu<br/>Leaf Spring Switch<br/>(1st Gen)
| image name        = FLS-1stGen-SwitchActuation.png
| manufacturer      = [[Fujitsu]]
| inventor          = Seisuke Kamei<br/>Hideo Nabetani<br/>Ryohei Kinoshita
| product code      = 
| switch type       = [[Switch terminology#Linear Switch|Linear]], clicky
| contact mechanism = [[Contact mechanism#Metal leaf|Metal dome]]
| lifetime          = 
| peak force        = 80 g
| patents           = [http://www.google.com/patents/US4370533 US4370533]
}}

{{Infobox dswitch
| name              = Fujitsu<br/>Leaf Spring Switch<br/>(2nd/3rd Gen)
| image name        = FLS-2nd3rdGen-SwitchActuation.png
| manufacturer      = [[Fujitsu]]
| inventor          = Seisuke Kamei<br/>Toshiaki Tanaka<br/>Kazutoshi Hayashi<br/>Akira Tanaka<br/>Ryohei Kinoshita
| product code      = 
| switch type       = [[Switch terminology#Linear Switch|Linear]]<br/>[[Switch terminology#Clicky Switch|Clicky]] (Rare)
| contact mechanism = [[Contact mechanism#Metal leaf|Metal dome]]
| lifetime          = 
| peak force        = 40 g, 45 g
| patents           = [http://www.google.com/patents/US4529849 US4529849]
| force graph       = [[File:FLS-2nd3rdGen-LinearForceCurve.png|200px]]
}}

==History==
The Fujitsu Leaf Spring switch seems to have been developed in the late 1970's as a way to reduce manufacturing costs for contact-based keyboard switch mechanisms (as opposed to sense-based mechanisms such as Hall Effect). The first iteration of the switch design used individual housings, and could be used individually, provided the switch is inserted into a stabilizing plate. The second design still used individual barrels for the switches, but it relied on the plate to suspend them over the leaf spring, similar to how [[IBM]] [[IBM Model F|Model F]] [[Switch terminology#Capacitive Contact Mechanism|capacitive]] [[Buckling Spring|buckling spring]] keyboards were designed. There is one confirmed keyboard that uses a one piece slider assembly, similar to the way the [[IBM]] [[Model M]] keyboard is designed.{{citation needed}}

There is also a known tactile version of the 3rd generation of the Fujitsu Leaf Spring switch. Though due to the design (the mechanism is inside the slider barrel), this newer design could be used in 2nd generation housings. Unfortunately, keyboards with this tactile switch are much more rare than the linear variants.

These switches are most famously used in the [[FM Towns]] line of keyboards as well as the [[Tandy 1000]] keyboards.

==1st Generation==
Individually housed leaf spring with corresponding button spring for actuation in each switch. Could be used individually. It used a cruciform slider with part of the leaf spring mechanism embedded into the slider, going through it and poking of the top of the cross.

The keycap mount dimensions are a fraction of a millimetre too large to fit Cherry keycaps; keycap insertion is very stiff. Testing with a modern Signature Keycaps novelty keycap yielded borderline success, while testing with a 2009 Filco keycap resulted in what appeared to be whitening of the plastic from stretching. Attempting to use Cherry MX mount keycaps is liable to lead to split keycap stems.

===Key feel===
The linear version is extremely smooth (even when dirty). Much heavier than the later generation switches. One of the best examples of well designed linear switches.

===Keycaps===
All known keycaps are [[Spherical keycap|spherical]] [[double-shot]], some nearly solid plastic. It uses a cruciform slider, as do many of the switches from the late 1970's through the 1980's.

<gallery widths="250px" heights="187px">
File:1st Generation switch..jpg    | 1st Generation clicky switch; note the tiny metal tip at the top of the stem
File:1st Generation switch top.jpg | 1st Generation clicky switch top; note the letter "F" at the base
File:1st Generation switches.JPG   | 1st Generation clicky switches
File:1st Generation keycaps.JPG    | 1st Generation keycaps
File:1st Generation keycaps..JPG   | 1st Generation keycaps
File:1st Generation keycaps...JPG  | 1st Generation keycaps
File:FLS-1stGen-Keycaps.jpg        | 1st Generation keycaps; the rightmost keycap is actually from a [[Fujitsu]] [[Fujitsu Magnetic Reed#Vertical Reed|vertical reed switch]], the other two could possibly be from a 1st generation or vertical reed switch, as the keycaps are compatible.{{citation needed}}
</gallery>

===Linear switch module===
The following switch is NOS purchased through AliExpress.

<gallery widths="250px" heights="187px">
File:Fujitsu 1GL -- top.jpg                        | Top, with Fujitsu branding
File:Fujitsu 1GL -- bottom.jpg                     | Bottom
File:Fujitsu 1GL -- base.jpg                       | Base, showing interesting cutout pattern in the plastic
File:Fujitsu 1GL -- opened.jpg                     | Opened; unlike the patent image, the contact assembly is a flat discrete module
File:Fujitsu 1GL -- partial disassembly.jpg        | Partial disassembly
File:Fujitsu 1GL -- slider.jpg                     | Slider with moulded-in actuator
File:Fujitsu 1GL -- slider, rear.jpg               | Slider rear
File:Fujitsu 1GL -- slider, metal insert point.jpg | Slider, showing where actuator leaf enters into the stem
</gallery>

==2nd Generation==
Individual barrels attached to a metal plate. Leaf spring and button spring attached to PCB below the plate. The slider is separate from the barrel and the keycap.
It uses rubber gaskets/stoppers at the bottom of keys to slow the keys down in case the user is bottoming out.

===Key feel===
Very smooth linear actuation, with a rubber stopper at the bottom of each key.

===Keycaps===
All known keycaps are [[Spherical keycap|spherical]] [[double-shot]]s, some double shots also have filled engravings. They fit directly onto the slider, similar to how the legends fit onto the two piece IBM [[Buckling Spring|buckling spring]] keycaps. Thick plastic is used. Keycaps are not compatible with the 1st Generation.

<gallery widths="250px" heights="187px">
File:FLS-2ndGen-Keycaps.jpg                 | 2nd Generation [[Spherical keycap|spherical]] doubleshot keycaps.
File:FLS-2ndGen-Stopper_Keycap.jpg          | 2nd Generation stopper, slider/housing, and reverse side of keycap.
File:FLS-2ndGen-LeafSprings-LED.jpg         | 2nd Generation leaf springs, and Caps Lock LED.
File:FLS-2ndGen-HousingSlider-Underside.jpg | 2nd Generation housing/slider underside, attached to metal plate.
</gallery>

==3rd Generation==
Individual barrels attached to a metal plate. Leaf spring and button spring attached to PCB below the plate. The slider is separate from the barrel and the keycap.
It does not use rubber gaskets/stoppers in the switches. Linear and clicky versions of the switch exist; the clicky version uses a mechanism within the slider, while the rest of the switch remains identical to the linear variety. The [[FMV77AV]] keyboard is known to use a single piece housing for all of the sliders, similar to the [[IBM]] [[Model M]] keyboard.

===Key feel===
====Linear====
Very smooth linear actuation.

====Clicky====
Weak tactile event, and a quiet clicking sound.

There is no known patent, a measured force curve is available elsewhere.<ref name="clickcurve" />

===Keycaps===
All known keycaps are [[Cylindrical keycap|cylindrical]] double shots, with a slightly unusual shape bearing no texture on the top. Keycaps are made of thick plastic and they are compatible with the 2nd Generation.

<gallery widths="250px" heights="187px">
File:FLS-3rdGen-SliderCasing.jpg                 | 3rd Generation slider and housing attached to metal plate.
File:FLS-3rdGen-LeafSpring.jpg                   | 3rd Generation leaf springs attached to PCB and LED.
File:FLS-3rdGen-Keycaps.jpg                      | 3rd Generation [[Cylindrical keycap|cylindrical]] keycaps with and without snap-in slider.
File:Fujitsuten_14-FLS3-3rdGen-Dismantled.jpg    | 3rd Generation switch, dismantled.<ref name="linear3rd" />
File:FLS-3rdGen-HousingSlider-Underside.jpg      | 3rd Generation switch underside, separate housing and plate construction, linear slider.
File:Oakb406_121-FLS3-3rdGen-Click_vs_Linear.jpg | 3rd Generation switches dismantled, linear (top) vs. clicky (bottom).<ref name="clicky3rd" />
<!--File:Fm77av-FLS-3rdGenVar-SinglePieceHousing.jpg | A variant of the 3rd Generation switch with single piece housing for all of the switches.<ref name="singlepiecehousing" />-->
</gallery>

==Keyboards==
It is believed that production of keyboards with these switches stopped in the late 1990s or perhaps early 2000s. Fujitsu later pushed its [[Fujitsu Peerless|Peerless]] switch.

===1st Generation Keyboards===
*DK'tronics ZX81/ZX Spectrum keyboard Mk1 <ref name="eden@home"/><ref name="world"/>
*Olympia People keyboard (Linear) <ref name="Deskthority"/>
*Sanyo MBC-2000/3000 keyboard (Clicky)<ref name="Deskthority1"/>

===3rd Generation Keyboards===
*[[Data General 6246]]-A (Clicky)
*Data General 6348-A Terminal Keyboard (Clicky)
*Epson Q503A<ref name="GH_Q503A" />
*[[HP 46010A|HP 46010A (Clicky)]]
*HP 46020 (Clicky)
*[[Tandy 1000]] (Linear)
*Tandy 3000 (Linear)

==References==
<references>
<ref name="clickcurve">Atelier Silencium — [http://www5f.biglobe.ne.jp/~silencium/keyboard/html/fujitsu.html Force curves for various 3rd Generation keyboards] Last updated 2010-02-20. Retrieved 2015-07-25.</ref>
<ref name="linear3rd">MouseFan — [http://mousefan.telcontar.net/image/fujitsuten.htm FUJITSU　テンキーボード　FMR30KB501 JAPAN] — Uses 3rd Generation switches. Retrieved 2015-07-25.</ref>
<ref name="clicky3rd">MouseFan — [http://mousefan.telcontar.net/image/oakb406.htm FUJITSU　オアシス　OAKB-406　JAPAN] — Uses 3rd Generation switches, click variant. Retrieved 2015-07-25.</ref>
<ref name="GH_Q503A">Geekhack — [http://geekhack.org/index.php?topic=52110.0 Espson Q503A Keyboard] Posted 2013-12-09. Retrieved 2015-07-25.</ref>
<ref name="Deskthority">Deskthority — [https://deskthority.net/keyboards-f2/olympia-people-microcomputer-keyboard-t13251.html Olympia People Microcomputer keyboard]</ref>
<ref name="Deskthority1">Deskthority — [https://deskthority.net/keyboards-f2/fujitsu-limited-keyboard-t9801.html Sanyo MBC-2000 / 3000 keyboard]</ref>
<ref name="eden@home">k1.spdns.de — [https://k1.spdns.de/Vintage/Sinclair/80/Peripherals/Keyboards/dk%27tronics%20Keyboard/ dK'tronics Keyboard for the ZX81]</ref>
<ref name="world">World of Spectrum — [http://www.worldofspectrum.org/infoseekid.cgi?id=1000123 DK'Tronics Keyboard]</ref>
</references>

[[Category:Fujitsu switches]]
[[Category:Clicky switches]]
[[Category:Linear switches]]
[[Category:Metal contact switches]]
[[Category:List of all keyboard switches]]