User Experience of the Non-Contact Electrostatic Capacitive Keyboard HHKB HYBRID Type-S

Introduction

As a Vim user (using VS Code with a Vim extension), I may have some biases while writing this article. Everyone has different preferences when it comes to keyboards, so please take this into consideration.

Back in February, I spent almost an entire day typing and coding on a mechanical keyboard (FILCO MANILA Air with brown switches) and found my fingers feeling quite fatigued, with a sense of helplessness while typing.

Taking this opportunity, I decided to try out the pinnacle of the keyboard world, which many engineers dream of - the HHKB. After purchasing it and using it for some time, I am very satisfied and would like to share my experience here. In this article, I will not only discuss my thoughts on the HHKB but also introduce the principles behind capacitive keyboards.

Keyboard Classification

First, let’s briefly introduce the different types of keyboards:

Membrane Keyboards

This is the type of keyboard you can buy for a few hundred dollars at a local store. It is the cheapest design among keyboards. When a key is pressed, conductive rubber contacts the circuit board to allow current to flow, enabling the microcontroller in the keyboard to detect changes. While convenient, membrane keyboards lose their elasticity over time, and detecting multiple key presses can easily become inaccurate, making them not the best choice for those who need to use the keyboard for long periods.

Mechanical Keyboards

Mechanical keyboards operate on principles similar to membrane keyboards, where pressing a key closes the circuit to allow the microcontroller to detect the key press. However, the design of mechanical keyboards utilizes springs, metal contacts, and switch axes to enable two metal contacts to touch and complete the circuit when a key is pressed. Depending on the switch type, such as blue, red, brown, or black, each switch provides a different typing feel. The presence of springs also offers a stronger tactile feedback.

Capacitive Keyboards

Now, let’s introduce the star of today’s discussion: the capacitive keyboard.

The principle behind capacitive keyboards is to detect whether a key is pressed through changes in capacitance. Two parallel electrode plates are placed, which can store electrical charges between them. By applying appropriate voltage to the plates, the capacitor can be charged. The capacitance is inversely proportional to the distance between the plates; the closer they are, the greater the capacitance, and thus a higher voltage can be detected.

The microcontroller uses an ADC (Analog to Digital Converter) to monitor voltage changes. When the voltage exceeds a certain threshold, it is determined that a key has been pressed. It is important to emphasize that the microcontroller does not directly monitor changes in capacitance, but rather the changes in voltage.

The biggest difference between capacitive keyboards and other keyboards is that they have no physical contacts; the circuit is always in a conductive state. Because there are no contacts, there is no wear and tear on parts, quieter keystrokes, longer lifespan, and no tactile bumps.

One point worth noting is that the conductive principle itself does not affect the feel of the keyboard; the feel is determined by the design of the springs and silicone. Therefore, even capacitive keyboards can have various tactile experiences depending on the manufacturer’s design.

Why Are Capacitive Keyboards So Expensive?

Let’s discuss why capacitive keyboards are so expensive. I believe there are two main reasons: "the fundamental difference in detection methods" and "the manufacturing process."

Fundamental Difference in Detection Methods

As mentioned earlier, the main reason lies in the principles involved. Traditional keyboards only need to detect whether the circuit is closed, while capacitive keyboards need to monitor continuous voltage changes to determine whether a key is pressed. This makes the entire circuit and firmware design a bit more complex.

Moreover, the capacitance values of the electrode plates in capacitive keyboards are typically around a few pF ($10^{-12}$ farads). Such small capacitance is easily affected by noise, so additional thought must go into eliminating interference to avoid misinterpreting key presses.

Manufacturing Process

The manufacturing process of capacitive keyboards is more complex than that of mechanical or membrane keyboards. It is necessary to ensure that the capacitance values for each key are similar, which requires more effort in circuit board design. You can check the internal structure of the HHKB at the 3:42 mark in the video below.

（As a side note, the feel of the keyboard comes from the springs and rubber inside）

For the reasons mentioned above, there are fewer companies that manufacture capacitive keyboards, and their prices are generally high, which attracts a smaller customer base.

For example, the highest specification model, the HHKB Professional HYBRID Type-S, costs around ¥35,200 (data from 2021, approximately NT$9,000). A good keyboard can last for several years; some colleagues have even used theirs for decades, leading to a yellowing of the keys. From a long-term perspective, this price is not expensive but rather an investment!

Currently, the more famous brands in the keyboard world are Realforce and HHKB, and recently the Chinese brand Niz has also become quite popular, with significantly lower prices.

Although the HHKB has a relatively small market in Taiwan, it is highly recognized in Japan. Just in the company I currently work for, over 100 people use HHKB keyboards daily, not to mention those who have two HHKB keyboards.

HHKB (Happy Hacking Keyboard)

The full name of HHKB is Happy Hacking Keyboard, originally designed by Professor Eiichi Wada of the University of Tokyo in collaboration with PFU Limited. The first version was released in 1996, and as of 2021, it marks its 25th anniversary.

One of the most famous quotes about the HHKB comes from Mr. Wada, the creator of HHKB:

"When cowboys in the American West lose their horses, they leave the bodies behind, but no matter how long they walk in the desert, they always carry their saddles. Horses are consumables, but saddles are an interface that fits their bodies. We must not forget that today, computers are consumables, but keyboards are important interfaces that we will use for a lifetime."

PFU also has an interesting paper titled Please Pay Your Attention to the Keyboard Layout, which discusses why the layout of the HHKB differs from that of standard keyboards. I highly recommend reading it!

HHKB Keyboard Layout

The HHKB was initially designed for developers who write code, with many key placements optimized for programming efficiency. However, even if you are not a developer, once you get used to the keyboard layout, you should be able to adapt; developers, however, will likely notice the benefits of this layout even more.

The key design of the HHKB pursues minimalism, removing all unnecessary keys, resulting in a keyboard with only 59 keys. You can also clearly see the differences in layout between the HHKB and other keyboards:

① Tab and Caps Lock in the Same Position

Caps Lock is not commonly used in general development (usually, you can just press Shift to switch to uppercase), yet it occupies a significant position. Therefore, in the HHKB layout, Caps Lock is omitted and placed in the same position as Tab, with pressing Fn + Tab acting as Caps Lock.

For Mac users, this may be inconvenient since they often use Caps Lock to switch input methods, unless they only need to input Chinese during work.

② Position of Ctrl Key

The Ctrl key is positioned to the left of A, which requires some time to get used to. However, once familiar, you’ll find this design quite excellent; your pinky doesn’t have to make large movements, resulting in comfort. For Vim users, navigating with Ctrl + F, Ctrl + B, and Ctrl + W becomes very convenient, as well as using Ctrl + C to close programs in the terminal.

③ No Arrow Keys

The HHKB does not have arrow keys! To use the up, down, left, and right keys, you need to press Fn + the respective arrow key, or remap them using software. If you want to play games that require arrow keys, you’ll need to make additional adjustments to use them. I use my pinky to hold down the Fn key while using the arrow keys, but this also requires some time to adapt.

If you frequently move the cursor using the arrow keys while coding, it might be a bit more challenging since keeping the pinky on Fn can easily lead to fatigue. This was also the reason I started using Vim; now, I mostly navigate using hjkl.

④ DELETE Above Enter

In standard keyboard layouts, the key above Enter is usually a backslash. However, the HHKB replaces this with DELETE (or Backspace). The most noticeable benefit is that when you press Backspace, your finger has to move a shorter distance.

⑤ Position of \ and `

The HHKB places these two keys above DELETE. At first, it may feel a bit awkward, but over time it becomes manageable since these keys aren’t used as frequently.

The biggest advantage of getting accustomed to the HHKB layout is that you can noticeably feel your hands moving less. For those who use the keyboard for extended periods, the most efficient way is to move quickly across the keyboard while minimizing travel distance, leading to less fatigue over time.

Typing Feel

For those used to the feel of mechanical keyboards, the typing experience on a capacitive keyboard may initially feel quite strange, even unacceptable. Due to the lack of physical contacts, capacitive keyboards do not offer as strong a tactile feedback as mechanical keyboards, making the typing feel very different. I recommend borrowing one from a friend or trying it out in person before purchasing, as the typing feel is something you need to experience for yourself.

Advantages

Suitable for Extended Use

Capacitive keyboards typically require less force to press the keys, making them suitable for long periods of typing or coding. I decided to try the HHKB after experiencing significant finger fatigue from using a mechanical keyboard all day.

In terms of typing feel, I still think mechanical keyboards have a slight edge, but the HHKB offers a different sensation that makes you want to type as soon as it's on the desk.

Portable

The current keyboard I use weighs 540g and measures 30cm x 10cm, making it ideal for taking out with a tablet or laptop.

Unique Keyboard Layout

Although it takes some time to get used to, once you become familiar with the HHKB's layout, programming becomes much more comfortable. Additionally, reducing the use of arrow keys has helped me to become more accustomed to using Vim, which is a positive outcome.

Disadvantages

Unique Keycaps

Standard mechanical keyboard keycaps typically use Cherry MX switches, but the HHKB's keycaps are produced by Topre, making them incompatible with each other.

If you want to replace the keycaps with your favorites, you may need to spend time searching for vendors, and the selection will be relatively limited. If you have a 3D printer at home, you might be able to print a few to try, but the quality may vary.

Expensive

A keyboard at such a high price point is not easy to justify. Not only is the keyboard itself costly, but various accessories are also pricey. When I received my keyboard, I discovered that it did not come with a cover, and I had to spend ¥4,400 to buy the official cover. While you might find cheaper options on Amazon, the official wooden palm rest is also ¥4,400. Buying the keyboard and all accessories will definitely strain your wallet.

Battery Replacement

I tend to leave my keyboard on, which may be why the battery drains faster. Under daily use of about 8 to 10 hours, I find myself needing to replace the battery roughly once a month.

Keyboard Layout

Once you get used to the HHKB layout, switching to another person's keyboard can feel cumbersome and time-consuming to adjust. Additionally, the HHKB does not have dedicated F1 to F12 keys; Fn must be pressed to access them, which can be a significant pain point for users who frequently use F1 to F12 as shortcuts. I enjoy compact keyboards, so this isn’t a major issue for me.

Hard to Purchase in Taiwan

There are virtually no physical channels in Taiwan to purchase HHKB keyboards directly; you can only obtain them through third-party purchases or on sites like amazon.jp (I heard they no longer ship to Taiwan?), which leads to less discussion around the HHKB in Taiwan. The most convenient and economical way to obtain one is to buy it while traveling to Japan. However, HHKB keyboards are rarely sold in regular retail stores. If you want to try one in person, you can refer to the official HHKB website, which has stores in Tokyo, Osaka, and Nagoya.

HHKB Model Introduction

There are currently three main models in the HHKB series: HHKB Professional HYBRID Type-S, HHKB Professional HYBRID, and HHKB Professional Classic. Each model comes in black and white colors, with versions that have and do not have key markings. Here’s a brief introduction to each model.

Classic

The wired version of the HHKB keyboard, which is also the most affordable model in the HHKB lineup.

HYBRID

HYBRID indicates that the keyboard offers both Bluetooth and wired functionality.

The HHKB Professional HYBRID Type-S that I currently use can switch between wireless and wired modes. This keyboard can pair with up to four Bluetooth devices, making it ideal for multi-device switching. For instance, you can use it with a PC in the office, connect it to a laptop while working outside, and then connect it to your personal computer at home. Simply press Fn + Ctrl + number keys to switch; it’s very convenient.

However, the keyboard requires AA batteries and does not have a rechargeable feature. While you can use rechargeable batteries as a substitute, it can be a bit cumbersome for users, and I find the battery consumption to be relatively fast, needing a change roughly once a month. This may also be due to my habit of not turning off the power.

HYBRID Type-S

Type-S refers to the silent version; in addition to the Bluetooth and wired functions mentioned in the HYBRID, the key sounds are quieter compared to the HYBRID version, though they are not completely silent. You can refer to the sound difference in this YouTube video (at 10:12).

If you decide to purchase from PFU, remember to select the English layout for the keyboard — do not select the Japanese version! The layouts are quite different.

Conclusion

In conclusion, I want to emphasize that typing feel is a highly subjective matter. While I really enjoy the feel of the HHKB, there will undoubtedly be others who find it unfamiliar. Especially for those who have used mechanical keyboards, the absence of tactile feedback can lead to a more significant difference in typing feel than one might expect. Therefore, I still recommend that everyone try it out for themselves before making a decision. With the recent drop in the yen exchange rate, now might be the best time to purchase one.

I hope everyone can find their ideal keyboard amidst the chaos of the keyboard wars.

Additional Resources

• [Twitter Share] The HHKB, featured in a Japanese drama, and the ATM keyboards in Japan are also capacitive?! This article mentions that the keyboard used in the drama "I Want to Leave Work on Time" is the HHKB. The ATM keyboard at Japan's 7-11 is also a capacitive keyboard.
• HHKB Pro2 Keyboard Review A rare Chinese review of the HHKB, although it is an older model.

You can find other Chinese articles in the PTT Key_Mou_Pad forum.

There are many more Japanese resources available:

• Official HHKB Website Articles HHKB regularly interviews prominent users and publishes the interviews as articles on their website.
• The Story of HHKB's Birth
• Sanpai TV - HHKB HYBRID Type-S Review
• Tobalog Comparison of HHKB HYBRID Type-S with Previous Models

Additionally, I think HHKB does a great job with their Twitter account, which interacts with other HHKB users almost daily, increasing user engagement with the brand and effectively leveraging trending topics to bring attention to HHKB.