Mitsumi hybrid switch
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This article requires additional photographic illustration — some sort of infobox photo, if that is at all possible |
| Manufacturer | Mitsumi |
|---|---|
| Switch type | Tactile; linear |
| Keycap mount | Various |
Mitsumi hybrid is a loose term that covers a number of related switch designs.
Contents
Description
"Hybrid" switches all use a central shaft that is supported by an external return spring or buckling rubber sleeve under the keycap. At the bottom of this shaft is some device which closes the electric circuit; this can either be conductive, or supply pressure. The device that closes the circuit provides a small amount of overtravel by allowing the conductive or pressure element to flex upwards.
The keycap mount varies between designs. The conductive rubber disc version has been found with the cylindrical Japanese mount. The pressure pad version has been found with a cruciform mount of unconfirmed dimensions. The conductive foot version is found with the hollow square "Mitsumi mount".
Variants
The total number of variants manufactured is not known. Listed below are the variants discovered to date.
Conductive rubber disc
Found in the Commodore 8032-SK and related machines, this has a small conductive rubber disc at the bottom of the slider. This has been found in an effectively linear form with a helical spring, and the circuit pathways are on a PCB. The following images are from an 8032-SK:
Top assembly, top view
Top assembly, bottom view
Hollow keycap and mount adapter
Front view of the switch
PCB
Slider with keycap attached; the spring does not normally extend that far down
Movable parts, including keycaps; the sliders use the old toothed cylindrical mount, and the keycap uses an adapter
Movable parts, including keycaps
Side view of slider
Bottom view of slider
Wide foot
These versions use a tall keystem with a laterally suspended pad. The pressure type (KSD Type) such as that found in the Atari 800 (pictured below) appears to use a pair of membranes over a PCB. These are pressure actuated using small rubber pads, attached to a rubber arc that flexes to provide the overtravel. KSR type covers the version with conductive pads over a plain PCB.
Rear view showing underside of PCB
PCB with two membrane layers
PCB removed, revealing the sliders
Slider plate
Switch components; note the external return springs and cruciform sliders
Conductive foot over membrane
This version provides a wide conductive rubber foot, attached to a similar rubber arc as in the pressure version. KPQ Type covers tactile switches and KPR Type covers linear switches; both types use a single membrane layer for the keyboard matrix.
Mitsumi-made Apple Keyboard II
Switch components from a KPQ-E99ZC
Conductive foot over PCB
KKQ and KKR types are externally visibly identical to KPQ and KPR types, but internally they use a PCB instead of a membrane sheet for the keyboard matrix.
Commodore CDTV keyboard seen from below, showing PCB
Commodore CDTV space bar arrangement
Commodore CDTV caps lock spring
Keyboards
Keyboards listed below cover switch types that do not yet have their own page, or where the switch type is unable to be determined from existing data.
- Some Magnavox VideoWriter keyboards (KKQ or KPQ, unconfirmed which)
