Olivetti dome with slider

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Template icon--Illustration.png This article requires additional photographic illustration — full disassembly, showing the helical spring and intermediate peg
Olivetti dome with slider
Olivetti dome with slider.jpg
Manufacturer Olivetti
Switch type Tactile
Sense method Conductive dome over PCB
Keycap mount Proprietary
Switch mount Plate mount
Patents EP0104956B1 (1983)

Olivetti dome with slider is a provisional name for a series of spring over dome switches from Olivetti using conductive domes over a PCB. It is a cost-reduced development of the similar-looking Olivetti snap action switch.

Description

The switch appears in a patent application by 'Ing. C. Olivetti & C., S.p.A.', filed in September 1983. The patent references the 1974 patent related to the Alps plate spring switch.

The rubber domes are discrete, and are held in place under the main switch housing by four pegs that insert into the corners of the dome. Each switch module is also discrete and removable: the ability to easily pull out a switch module from the top of the keyboard for replacement is cited as a design goal in the patent.

The design is similar to that of Fujitsu Peerless in that there is a helical spring between the slider and the dome. Instead of a plastic tube to keep the spring captive, a peg is placed inside the spring instead.[1] The patent describes in detail the interaction between the helical spring and rubber dome, illustrated with force graphs; while not specified explicitly, it is clear from the explanation and diagrams that this design allows for both overtravel and hysteresis. When the dome collapses, the spring extends to fill the gap, leading to an overtravel period where the only force is from the spring. When releasing the key, the dome does not spring back until the force from the helical spring has been sufficiently reduced.

Red and white sliders are known to exist. The significance of the slider colour is not yet understood.

Keyboards

  • AT&T PC6300 keyboard (KBD 302) (red sliders)[2]
  • Logabax Persona 1600 Keyboard (appears to be a re-brand of ANK 2462) (red sliders)[3]
  • Olivetti Keyboard 1 (red sliders)
  • Olivetti Keyboard 2 (red sliders)[1]
  • Olivetti Keyboard 2 (ANK 2462) (white sliders)[4]
  • Olivetti M20HD keyboard (white sliders)[5]
  • Olivetti M21 keyboard (red)[6]
  • Xerox 6060 Keyboard (appears to be a re-brand of the ANK 2463) (white sliders)[7]

Gallery

The following images are of an Olivetti Keyboard 2.

References

  1. 1.0 1.1 Geekhack — Olivetti Personal Computer Keyboard 2 Posted 2013-06-07. Retrieved 2015-07-31.
  2. Imgur — AT&T PC6300 KBD 302 Dated 2013-12-31. Retrieved 2015-07-31.
  3. System.cfg — Logabax Restauration Persona 1600 Dated 2010-07-25. Retrieved 2015-07-31.
  4. Deskthority — Olivetti Keyboard 2 Rubberdome
  5. z80ne.com — Antonio Busi's M20 BC and ST Retrieved 2015-07-31.
  6. Nightfall Blog — Repairing a defective Olivetti M21 (page 4) Dated 2014-02-23. Retrieved 2015-07-31.
  7. reddit — An old Xerox keyboard with a switch I don't recognize... Dated 2013-12-30. Retrieved 2015-07-31.