Mitsumi miniature mechanical
|This article requires photographic illustration|
|Switch type||Linear, tactile, clicky|
|Sense method||Metal leaf|
|Keycap mount||Mitsumi mount, Cherry MX mount, Alps mount|
|Switch mount||Plate mount/PCB mount|
Mitsumi miniature mechanical switches are not only low-profile, but also very shallow front-to-back. The total size (not including legs or slider) is approximately 15.6 mm wide by 9.5 mm deep and 9.2 mm tall. Height above the plate is around 5.4 mm without the slider, and the total height including slider is around 13.5 mm. Total travel appears to be 4.3 to 4.5 mm. The switch has a metal top that is secured on either side by ramps on the outside of the shell and on the inside of the plate retention clips, making the switch extremely hard to open. The metal top bears either the old ("ミツミ": mi-tsu-mi) or new Mitsumi logo stamped into the side. The slider can be Mitsumi mount, Cherry MX mount or, in rare cases, Alps mount.
The switches are designed to be plate-mounted, but with six legs, they appear to be designed to support PCB mounting also, especially considering their form factor. In many cases, these switches were indeed PCB mounted. The front left and back left legs are electrically connected, as are the front right and back right legs. The switch contacts connect the left side legs to the right side legs. The left and right centre legs are part of the metal lid and are therefore connected to each other, forming a circuit jumper.
The design of the contacts varies, but all switches examined to date follow the same overall design. A vertical plastic frame holds a thin sheet of metal on one side which bears a raised, gold-plated prism. A flexible copper strip is mounted into the opposite side, which reaches across the space within the frame. The copper strip is held away from the slider by either folds in the metal or a small plastic follower inserted through the strip. When the slider is depressed, the follower or extended section of the strip are released into a recess in the slider, and fingers at the end of this strip touch the stationary contact.
The return spring can be mounted either vertically (as with typical switches) or slung horizontally under the slider. The latter design provides tactility using only a single spring; the base nub in these switches (that normally locates a vertical spring) is modified with a lateral groove for the spring to slide over. As the slider in a tactile switch is depressed, the lateral spring is stretched over the base nub; as the force on the spring rises, it will suddenly give, generating tactility.
A batch of yellow tactile switches purchased by Devlin have been confirmed to be highly tactile, while most people report the switches to be only lightly tactile.[Citation needed]
The construction of the linear and tactile versions are well documented; a clicky version also exists, but thus far, the internals are not known.
The switch case is reported to break sometimes if a keycap is removed without due care.[Citation needed]
Examination of Mitsumi model numbers and late 90s and early 2000s catalogue pages suggests that linear and tactile switches are placed into separate series. Devlin purchased switches with part number KLT-11 from Mitsumi in the past, before switching to Cherry MX; these switches are tactile and use Cherry MX mount. Numeric keypads with linear switches with Mitsumi mount fall under KLM Type, suggesting at least two series of miniature mechanical switches: KLM Type (linear) and KLT Type (tactile). The reported existence of clicky switches in this family suggests potentially a third series may exist.
Although Mitsumi use structured part numbers, the derivation of "KLT-11" is not known. Whether a single type (e.g. KLT) covers multiple keycap mounts remains unconfirmed.
One curious characteristic of the design is that the aperture in the metal top is the precise size required to accommodate an Alps mount slider, with gaps left at the each side between the top and all other sliders. This suggests that the Alps mount version came first, or that it was always intended to be possible without any modification to the stamped metal parts.
- Burton J31KB001 numeric keypad (green, linear)
- Epson PCLTP2 (white, tactile)
- Toshiba PA7354E (green, linear)
- Toshiba J31TP001 (green, linear)
Cherry MX mount
- Some Chicony KB-5161A (yellow)
- Chicony KB-5170 (white, tactile)
- Some Chicony KB-5191/5192 in both green and yellow (both tactile)
- Dataware KB-6251EM (yellow, tactile)
- Some Monterey K101 (yellow)
- NTC KB-6252CH (yellow, tactile)
- Quantel keypad (peach, clicky)
- Quantel keypad (yellow)
- Some Zenith ZKB-2 (white, linear)
- Some Zenith ZKB-2R (white; sometimes with and green for space bar)
Yellow tactile Cherry MX mount
Comparison with Cherry MX
A comparison of the yellow tactile switch with its nearest Cherry MX equivalent, Cherry MX Clear:
- Google+ — Quantel (Old) Dated 2012-02-17. Retrieved 2015-07-29.
- MouseFan — BURTON J31KB001 (Japanese only) Dated 2003-08-31. Retrieved 2015-07-29.
- MouseFan — EPSON テンキーパッド PCLTP2 (Japanese only) Dated 2003-08-03. Retrieved 2015-07-29.
- Deskthority — Toshiba Numeric Keypad
- ちゃたりたいね — 東芝 J31TP001 テンキーパッド MITSUMI 井型 緑軸 リニア
- Deskthority — Chicony KB-5170 - The TK that could
- Google+ — Chicony KB-5192 (Mitsumi-Cherry Hybrid Switches) Dated 2011-11-26. Retrieved 2015-07-29.
- ちゃたりたいね — Chicony KB-5191 E8H5IKKB-5191 MITSUMI十字 黄軸 タクタイル (Japanese only) Dated 2014-02-08. Retrieved 2015-07-29.
Imgur — Keyboards(DEAD!)
- Google+ — Quantel (New, more complete) Dated 2012-02-17. Retrieved 2015-07-29.
- Sandy — zkb-2
- ちゃたりたいね — ZENITH ZKB-2R MITSUMI ALPSマウント 白軸 リニア