Cherry solid state capacitive
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| Manufacturer | Cherry |
|---|---|
| Switch type | Linear |
| Sense method | Capacitive |
| Patents |
US 4445164 (1982) US 4466046 (1983) |
Cherry solid state capacitive refers to foam and foil capacitive switches from Cherry. Two distinct families of switch exist. Production of these switches may not have been moved to Germany when Cherry relocated their manufacturing from Illinois, USA to Germany, and no records are believed to remain at Cherry of any form of foam and foil switch.
Families
Cross stem
Based on the data in the 1982 US keyboard catalogue, the switch uses discrete spring/slider assemblies. The switches are not fully discrete as they rely on a dedicated PCB and controller. The earliest catalogue appearance discovered to date is 1979.
US patent 4445164, filed on the 5th of May 5 1982, describes the illuminated version of the switch. A patent for the switch itself has yet to be located.
The keystem is cruciform, and has ridges to grip the keycap.
There are at least two variations of the shell; the most distinct difference is the design of the plate retention clips:
Catalogue KB79-2 image
Catalogue KB79-2R image (May 1982)
The later design looks like it may be easier to remove from the keyboard for replacement. The following construction diagram is from catalogue KB72-2R; the older catalogue has a very similar diagram:
The following images are from a Cherry B4VB-5601 keyboard, which uses the later design:
Switches
Dummy switch used as a stabiliser
Switches with springs removed
Disassembly slider assembly
Slider
Slider with foam visible
Capacitance sense pads on the PCB
Shamrock
There are two variants of this, both found from 1983. The "barred" version has a bar across the slot in the slider, which is fully open in the "open" version. This version is presumably the DIN-compliant redesign.
US patent 4466046 filed in 1983 depicts the new switch shell, but continues to primarily describe and solely depict the coil spring–based design. The possibility of using a foam pad and foil sheet is however mentioned briefly in the patent. US patent 4458293, filed in 1982, shows a switch very similar in shape to the cross stem version but this also uses a metal spring to control the capacitance. At this point, it is not clear whether the metal spring was intended to replace the foam pad, as the only known examples of this entire series are all foam and foil.
Barred vs open sliders
Barred switches in the Cherry KFN3-8358
Underside of the Cherry KFN3-8351
Underside detail
Keyboards
- ADDS Regent 25 (1982)[1]
- Cherry B4VB-5601 (cross stem, newer, 1984)
- Cherry KFN3-8351 (shamrock open, 1983)
- Cherry KFN3-8358 (shamrock barred, 1983)
- Control Data 721
- Crumar GDS keyboard (cross stem)[2]
References
- ↑ Deskthority — Various resto-mods Posted 2021-05-06.
- ↑ Vintage Synth Explorer Forums — The Crumar GDS Restoration Blog... page 6; Posted 2014-09-24. Retrieved 2015-07-25.
