HHKB Professional Series keyboards

The HHKB Professional is a series of compact keyboards using Topre electrostatic capacitive switches produced by PFU since December 2003, with the layout designed by Japanese computer scientist Eiiti Wada optimized for use with UNIX systems.¹⁾

The HHKB Professional series of keyboards primarily use a modified US ANSI layout, with specified JP models employing a modified JIS layout. The “Professional” name is used to differenciate from other Happy Hacking keyboards in that they use Topre switches.

All keyboards in the Professional line consist of a top and a bottom plastic case. The top handles the integrated Topre plastic plate with switch housings as well as the standoff attached PCB with rubber domes over conical springs. The top and bottom case assemble with 3 black screws on the bottom as well as 3 hidden clips along the front edge of the keyboard.

On the bottom case there are two flip-out feet to adjust the typing angle as well as four anti-slip rubber pads available on the Professional 3 keyboards.

The Happy Hacking Keyboard Professional (PD-KB300XX) released in December 2003 was the first HHKB to use Topre electrostatic capacitive switch technology instead of the prior rubber dome over membrane design. It was available in either white or charcoal colourways with the option of printed or blank keycaps. It features a mini-USB port for plugging in the included cable. It was later discontinued in December 2006.

In March 2006, the HHKB Professional 2 (PD-KB400XX) was released as a successor to the Professional 1 with an integrated 2-port USB hub at the rear of the keyboard to allow for connectivity with a wide range of low-powered USB peripherals such as computer mice.

In 2011, PFU released the HHKB Professional Type-S variant of the Professional 2 with silenced Topre switches. The silenced variant of the Topre switch achieves the dampened sound with a foam and plastic o-ring around the slider to soften the sound on the upstroke. The 0.3mm longer stem is used to counteract the lost travel from the silencing rings.

In 2016, the HHKB Professional BT (PD-KB6XXXX) was released to be the first model with built-in Bluetooth capabilities. The keyboard is wireless only, so the USB port is exclusively used for power transfer. The indicator light on the top of the case is used to communicate the battery and pairing status.

The Professional 2 line is known to be discontinued in late 2019.

In December 2019, PFU released the third-generation models of the HHKB Professional, comprising of the Classic, Hybrid and both of them featuring Type-S variants. The third-generation omits the USB hub but includes USB-C connectivity in place of the outdated mini-USB port. The new case design features sharper bezels and rounded corners to the Professional 2, similar to the Professional BT. The HHKB branding has been relocated from the bottom right to the top of the case. It is available in both white and charcoal colourways and it is known that the white cases have been improved by using UV-resistant AES plastic instead of prior ABS that have been known to yellow significantly. Keycaps also still have the option of printed and blanks but all spacebars are now made of PBT plastic.

The Classic is the direct successor to the Professional 2, but features the new design styling of sharper bezels and rounded corners.

The Hybrid follows similar design as the Professional BT with the battery bump but with the option for both wired and wireless connectivity. A headlining feature is the option to seamlessly connect with up to 4 devices with built-in bluetooth.

In November 2021, as a celebration of the 25th anniversary of the first HHKB concept in 1995 named the 'Aleph keyboard', PFU first released the HHKB Hybrid Type-S Snow which is pure white in colour and includes a special anniversary HHKB25 'Fn' key, with only 250 units being made available in Europe.²⁾ It was later rereleased and the printed keycaps option features a centred Helvetica-style lite typeface.