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Hirose Cherry Precision

Hirose Cherry Precision Co., Ltd. (“Hirose Cherry”) was a joint venture between Hirose Electric Co., Ltd. (at that time the exclusive Cherry distributor in Japan) and Cherry Electrical Products. The Company Profile (会社概要) page on the former Hirose Cherry website stated that the company was founded (“創業”) on the 15th of August 1968, and established (“設立”) on the 6th of March 1973. The あゆみ (chronology or milestones) page gave the joint venture as being concluded in March 1973, and the company as being established in May 1973.

Over their lifetime, Hirose Cherry appear to have both imported German switches and manufactured their own switches.

Hirose provided me with a number of old datasheets. These give fascinating insights into their product range, but only cover a portion of the products that we have discovered to date. It appears that no documents at their office that offer a detailed view of each series. Sadly I am not permitted to publish these datasheets here, even though there is nothing technical given in any of them that we do not already know from other Cherry literature, and despite repeated warnings from Hirose that they are no longer sold. Attempting to convince them otherwise was met with complete silence.

Keystem

Hirose MX and M8 switches are notable for sharing a keycap mount that is different to those of their Western counterparts. The following diagram shows the various 6 mm and 8 mm keystems; you can see that the Hirose switches share a common mount that is different from the 6 and 8 mm mounts used in the USA and Germany:

US and German keycaps will fit on Hirose switches, but Hirose keycaps will not fit on US and German switches.

No mention is made in the 1988 part number schema for the Hirose keystem. However, the Hirose MX datasheet uses stem type N, and switch type 0.

Types

M8, MD, MJ

Hirose manufactured their own variant of M8 series. They also introduced three more variants; two of these (MD and MJ series) were mentioned on the chronology/milestones page of the former Hirose Cherry website, which is why I returned to Hirose for answers:

Original text Translation
昭和58年4月 低背形キースイッチ(MDシリーズ)発売。 April 1983 Low-profile keyswitch (MD series) was released.
昭和58年4月 低背形キースイッチ(MJシリーズ)発売。 April 1983 Low-profile keyswitch (MJ series) was released.

The datasheet that covers M8, MD and MJ is not clear. All three types are shown with the Hirose M8 slider planform, but the M8 drawing appears to show a regular MX-style keystem. MD and MJ are shown with Hirose keystems. The keystem details are not clarified for any variant, but all types are shown with the shorter 3.5 mm keystem.

In summary, the types are as follows:

Series Travel Shell height
M83A 2.5 mm 6.7 mm
M83S 1.5 mm 6.7 mm
MD 3 mm 7.3 mm
MJ 4 mm 7.7 mm

Shell height includes the stand-off nubs, i.e. it is the distance from the top of the shell to the top of the PCB.

It turns out that Epson PX-8 used MD switches, with M83S used for the top row (Esc through PF5); I received some switches from this keyboard from UncleFan and I was able to match them with the types shown in the datasheet.

Switches with the Hirose planform but with German M81/M82–style contacts have been found in the German-made Basis 108 microcomputer keyboard, used for the unstabilised wider keycaps. The keystem however is German-style, suggesting that these special switches were moulded afresh in Germany. This type is not given in the M8 brochure.

The switch contacts in Hirose M8 are trapezoidal rather than the triangular and cylindrical designs of US and German switches. The small size of the parts makes determination of the exact design difficult, but the front faces of the contacts must have a slight curve or ridge.

M85

M85 does not appear to be a computer keyboard switch. This appears to be a Hirose product, using again keystem type N (defined this time as “キートップ?合 / 先端形状”, with a kanji that remains resolutely illegible). This type was also listed in the Hirose chronology:

Original text 昭和62年4月 センターLED式照光式押釦スイッチ(M85シリーズ)発売。
Translation April 1987 LED-type illuminated pushbutton switch (M85 series) released.

This type was at one stage appended to the German M8 brochure, but the relationship with M8 remains a mystery, as M8 and M85 bear no resemblance to one another.

MX

It was suggested somewhere that Japan got MX switches first; Hirose themselves told me that “Originally, German MX switch was based on Japan version.” This would account for the Hirose datasheet using switch type 0 (MX Black is type 1), but why would a Japanese type still use keystem N? MD and MJ series use keystem 1, but Hirose MX uses keystem 0. The keystem is again shown as German-style but 3.5 mm tall.

The MX patent lists the inventors as Gunter Murmann and Gunter Bauer, and it is not clear whether they designed the switch, or whether they adapted a Japanese design to provide movement differential. What we do know is that early Hirose MX switches were branded “HCP”, instead of “Cherry”.

ML

Cherry ML was listed on the Hirose Cherry website. It is likely that these were imported from Germany. The only listed “MLシリーズキースイッチ” (ML series key switch) and “G84-4100シリーズ超薄形コンパクトキーボード” (G84-4100 Series Ultra Thin Compact Keyboard). The pictures were never archived.

Capacitive

Hirose Cherry were granted patent JPS59828A in January 1984 for capacitive keyboards. Nothing is known about Hirose capacitive keyboards, although Cherry in the US had introduced foam-and-foil capacitive keyboards by 1979.