Matsushita, now Panasonic, is a Japanese manufacturer. They supplied the Hall ICs for Omron B2x switches. They also produced keyboards of their own, including for some models of Acorn Archimedes computers.
Matsushita and Panasonic keyboards are poorly documented; the photos that do or did exist were often of poor quality or have since been lost. All known examples at present are membrane-based. Matsushita keyboards can be identified by a Matsushita logo on the sticker affixed to the metal backplate or printed onto the membrane sheets.
Spring over membrane
A single example of a more traditional spring over membrane keyboard is known, found in an Ericsson Portable PC. As with Alps and SMK designs, each plunger is housed in a removable module that appears to contain two springs: one for the return force and one for membrane actuation pressure.The plunger module composition is not confirmed, however. The matrix appears to be two membrane sheets over a PCB, and the assembly appears to provide N-key rollover judging by the lines of diodes positioned in between the rows of keys. The PCB was designed for both through-hole (components mounted on the bottom) and surface-mount (components mounted on the top), with surface mount having been chosen in the instance above. The keyboard module is part ESU-2176, serial 2972. There is no date information readable in any of the photographs, but the Portable PC itself was introduced in 1985. The old triangle logo is used on the product label.
Prong over membrane
Most Matsushita and Panasonic keyboads are “prong over membrane”: full travel uses a large coil spring, but the membrane pressure is applied using a moulded-in plastic prong. The known examples are all integrated mount: there is no separate plunger. Keyboards of this design are commonly found in Amstrad keyboards, and their origin is a mystery. Disassembly photos show that Matsushita and Mitsumi were both keyboard suppliers to Amstrad, but many Amstrad keyboards of this general design are Amstrad-branded, and it is unclear to what extent Matsushita were involved. It does appear that Amstrad had their own production facilities, and they could have produced these keyboards under licence, rather than subcontract production to Matsushita. Jacob Alexander possesses an Amstrad prong-over-membrane keyboard that bears Matsushita’s diamond logo on the membranes, but photos of this keyboard can no longer be found, and such markings are typically absent.
Known examples include:
- Acorn BBC A3000 keyboard (the Matsushita logo is visible, but not the label with the part number)
- Acorn A3010 (and possibly also the A3020) — a label can be seen that matches that of the unknown Panasonic keyboard, and the site owner has confirmed that it bears a Matsushita logo
- Panasonic FW-TK101 keypad, with a part number that appears to read ESU44LN032CB, serial 690.