Software, Hardware, and Capacitive Buttons

Johnny Thai
Jun 26, 2015 · 11 min read

Briefing

Buttons on a smartphone are obviously important. They work in tandem with the user―to either help the user, or to serve the user―and that’s not a bad thing at all.

Without buttons, it becomes entirely impossible for a smartphone, or even any piece of technology for that matter, to function at all, which renders this article as completely useless.

So let’s step back a bit. I’m talking about primary buttons.

Primary buttons, in my own definition, are the main buttons on a smartphone; volume rockers and sleep/wake button exempt.

There are three different kinds of primary buttons* that will be discussed in this article:

  • Hardware Buttons
  • Software Buttons
  • Capacitive Buttons

*trackballs don’t count!

Examples

  • The iPhone’s primary button is the home button―which is a hardware button.
  • The Nexus 6's primary buttons are the back button, home button, and overview button―which are software buttons.
  • The Samsung Galaxy S6's primary buttons are the home button―a hardware button―while the back and overview buttons are capacitive buttons.

While buttons may be overlooked as unimportant and negligible, each type of button has its own strengths and weaknesses, which I will discuss below.


Hardware Buttons

Background and Positives

Hardware buttons are the simplest. The user knows exactly what it is (a button), and at the same time they provide a tactile feedback that tells the user that the button has been pressed.

Plus, they're everywhere!

People naturally push buttons out of curiosity, so it makes sense for a physical button to exist in order to teach the user what the button does.

Typically, hardware buttons require more technology under the hood such as the contact points and the physical home button itself. The most common hardware button used in smartphones are push button switches, and more specifically, use momentary contacts―they only work for as long as they're pressed.

In addition, hardware buttons can also function as a wake button. The iPhone and Samsung Galaxy line, for example, both allow their home buttons to wake the device, while leaving the sleep function exclusively for the sleep/wake button. This function is not available for capacitive or software buttons, as they require power to be used in the first place; a definite positive for momentary contacts.

Nowadays, Apple and Samsung have engineered fingerprint scanners into their home buttons to give them even more function and versatility. They now serve as a way to secure the device, as well as for paying things with a fingerprint.

The result is a reliable, tactile button that will work whenever pressed, but that leaves us with downsides.

Negatives

Since it is a hardware button, it can break.

What good is a button if it doesn’t work?

Pressing buttons too many times can cause the contacts to degrade and eventually stop working entirely. In some circumstances, dust, dirt, or anything else can get under the device and in and around the contacts, causing a disconnection, resulting in the buttons to become mushy, or even worse― get stuck.

In my own experience, my iPhone 4's home button eventually needed more than one press to work, while my iPod Touch’s home button is still working flawlessly. It mainly depends on the usage per person.

From a manufacturing and designing standpoint, the inclusion of a hardware button requires more bezel use on the phone. For instance, the iPhone has a large bottom bezel (known as the chin) footprint to house the home button.

As a result, the top portion of the iPhone (forehead) is also large to keep symmetry on both sides. (Keep in mind that is only with Apple’s design philosophy)
Therefore, a larger bezel on the top or bottom results in an entirely larger phone with a smaller screen size.

To put in perspective, the LG G2 has a 5.2" display with software buttons, which is around the same height as the iPhone 6 with a 4.7" display and home button.

Ironically, many users, whether Android or iPhone users, have come to seek refuge by finding software features to aid them in the degradation of their primary buttons―after all, most people are stuck with their smartphone with a 2 year contract; it would be wise to preserve its life by only using it when necessary.

The iPhone has Assistive Touch, which is a software button that performs almost every hardware-related task, while Samsung has a similar feature.

Even Google has switched to software buttons long ago, but is it more intuitive? I'll touch on that soon.


Capacitive Buttons

PC: Jeffery Akuamoah-Boateng; LG G4

Background and Positives

Capacitive buttons are actually really interesting in the way that they work. The human body contains the ability to hold an electric charge and in practice, acts as a capacitor. Skipping all the engineering voodoo-nonsense, when your finger comes in contact with a capacitive button, it causes an interference with the capacitance. It changes the total capacitance, and the button can be engineered to perform its function when the disturbance occurs.

In smartphones, there is almost always more than one capacitive button because the workload is divided between 2 or more instances.
In the past, there used to be the menu button, search button, home button, and back button. The HTC Nexus One even went as far as having all of these buttons with a trackball* on top of that! In fact, the trackball was also the notification light.
*still not counting it as a button, sorry.

The upside to having capacitive buttons is flexibility, but within a confined box.
Capacitive buttons may be weirder than hardware buttons for first-time users. To emulate a physical button’s feedback, they vibrate when touched (but can be disabled) and light up to tell the user which button they had pressed.

They may be more practical by offering the user more options at a time, but they are mainly limited to Android.
The back button and home button are the most used capacitive buttons, with the menu button coming close.

In recent times, Google simplified the buttons to back, home, and recents.
Capacitive buttons rarely break because there’s really nothing to break in the first place, except the sensors.

They're highly responsive and require less effort to press than a physical button. In some circumstances, it may be more practical to tap the capacitive buttons because pressing down takes more energy, which is why some manufacturers still use capacitive buttons to this day.

Some manufacturers and custom ROMs mimic the ability that physical buttons have to add gestures to capacitive buttons. OnePlus and Cyanogenmod are well known to allow capacitive buttons to be double-tapped to activate recents, or even enabling the flashlight.

Negatives

Capacitive buttons and physical buttons share the same fate: they take up space in the bezel, but that’s not the only thing.

There was never a rule as to how capacitive buttons should be laid out on a smartphone. As a result, manufacturers put the capacitive buttons in any order they saw fit, which wreaks havoc to consumers when changing phones.

Furthermore, the icon for the capacitive buttons also vary between manufacturers. This adds on to the exclusivity of a manufacturer while causing fragmentation among Android phones.

Most notably, Samsung and LG’s capacitive buttons were exact opposites. Samsung put their back button on the right side, and menu/recents on the left side, while LG put their back button on the left side and menu/recents on the right side.

Samsung began using a combination of hardware buttons and capacitive buttons with the home button flanked as a hardware button and the back/recents as capacitive after the Samsung Galaxy SII.

LG stuck with capacitive buttons until they moved straight to software buttons after the LG Optimus G.

Finally, capacitive buttons may be more accidentally pressed than a physical button because of the recessed effort it takes to press. In landscape, phones with capacitive buttons also have less space to grab on the sides. On phones with physical buttons such as the iPhone, users can easily rest their thumb on an empty space when in landscape. If phones have too many capacitive buttons, there are no spaces at all to rest thumbs on in landscape.

Google eventually got rid of the idea of a menu button and completely replaced it with the recents/overview button we all know today. The menu button now lives within software.

With the debut of the Galaxy Nexus, software buttons were born, and with a specific layout: back, home, and recents in their respective order.


Software Buttons

Software buttons, on-screen buttons, navbar, navigation buttons―you name it!

Background and Positives

Google set a precedent when they started using software buttons over hardware/capacitive buttons on the Galaxy Nexus.
Software buttons are exact replicas of capacitive buttons, mirrored onto the screen itself. They even vibrate, if you want them to. The result?
Customization, larger screens, smaller bezels, and sleeker phones―at least in theory.

In practice, that’s pretty accurate!

With root, you can customize the look of the buttons. LG’s skin, as well as custom ROMs allow the ability to add and rearrange buttons to the user’s liking.
Phones like the Nexus 6 have a very small chin bezel thanks to software buttons. What’s living on the bezel? Front facing speakers! It is proof that phones can have minimal bezel without buttons.

Without buttons, phones look aesthetically more pleasing because they are cleaner. No distracting bells and whistles―just a big, fat screen and the typical front facing camera and speaker grille(s) on the front.

People may think that software buttons take up precious screen estate, but since they're software buttons and not physical hardware, they can be hidden in apps to create a more immersive experience. Google allows the navbar and statusbar to be hidden with Immersive Mode in 4.4 KitKat.

In Lollipop, Google simplified their design to simple geometric shapes―a triangle, circle, and square―reminiscent of a certain game console’s controller.

Multi-tasking and using a smartphone or tablet with software buttons may be the fastest of them all, too. They require less effort to press than a physical button or capacitive button because they are as natural as a tap on the screen.

Gestures also help create more utility to the buttons. Google introduced a swipe-up to Google Search/Google Now, which ties into the ecosystem without unusual breaks or disconnects. Now, users can do a quick Google-search from anywhere with a simple swipe-up gesture.

Software buttons have proven themselves so much that some manufacturers have stopped using capacitive and physical buttons completely.

Examples:

  • The HTC One M7 has capacitive buttons. Now every HTC flagship has software buttons.
  • The LG Optimus G has capacitive buttons. Now every LG flagship has software buttons.
  • The Moto X flagships started with software buttons.
  • The Sony Xperia line started with software buttons.

Manufacturers that adopt Google’s software buttons in the “correct” order means that consumers are able to pick up just about any flagship today and are able to use them without a new learning curve.

Even Microsoft has adopted software buttons. I think that speaks volumes when I say that software buttons are the future.

Negatives

Although Google released the API for Immersive Mode, not many apps are utilizing it. Reading related apps such as Google Play Books were one of the first to support Immersive Mode, but even games at the top of the chain do not utilize it. The result is wasted screen space and increase likelihood of exiting the game while playing.

Since the elements are bled into the screen rather than onto the bezel, it could take more time to adjust. In my own experience, I adapted to it within the first minute. I thought it was ingenious.

Users that switch to a device with on-screen buttons may have accidentally pressed home or back rather than the space bar while typing with a keyboard. No such accidental happenings occur with physical buttons.
Software buttons also do not exist until the screen is on.

Consequently, the only option to wake the device is with the sleep/wake button or with software features.
Google as well as other manufacturers such as LG and HTC resort to workarounds to wake the device.

With LG’s inclusion of rear keys, they created Knock On, which is double-tap the screen to wake the device. HTC followed suit one year later on the M8.

Google’s ambient-mode follows Motorola’s Active Display, which wakes the device when picked up and breathes notifications when on a desk.
Motorola one-upped everyone with the use of infrared lasers to wake up the device on the latest Moto X 2014.

While these new software features may be cooler and more flashy, sometimes a physical button just proves to work every single time. Luckily, all these funky methods of waking a device can be disabled, and anyone can still use the physical sleep/wake buttons on every device.

In some cases, software buttons have a small delay when pressed, but it depends solely on the manufacturer software that the phone is wielding, such as the OnePlus One or LG G3. Luckily, software fixes can solve the issues―which they did.

All in all, software buttons can either be your best friend or biggest nightmare. Learn how to adapt to them to avoid input errors.

I never accidentally press my software buttons because I've adapted. I can pick up any device with software buttons and do the same.

One last issue that only occurs for AMOLED screens: screen burn-in.

If elements on a screen are not “refreshing” enough, they can burn into the screen. Since on-screen buttons are practically there until you’re in an app that can hide them, they get stuck there. It’s almost never noticeable until you actually look for it with a grey background, but it happens.

It’s happened with my Nexus 6. The solution: either hide your navbar or invert your screen every once in a while to even out the burn. They work. I’ve used them.


Final Thoughts

After using all three of these buttons on my smartphones, I have to admit that software buttons are my personal favorite. I don't want to deal with a broken home button or fear that it will break, nor do I enjoy using blinding capacitive buttons in the dark (you can disable them, but phones like the S6 require an entire app to do so).

Software buttons have always been more reliable than any other type of button, and for good reason. They offer small features such as swiping to Google Now in an instant, more screen estate when hidden, and are much faster and responsive than ever before.

Taps are just more natural than presses, too. If I were to rank them, it would definitely go like this:

  1. Software Buttons
  2. Capacitive Buttons
  3. Physical/Hardware Buttons
  4. Physical and Capacitive Buttons (I’m looking at you, Samsung!)

However, I also like choice. I have to give props to OnePlus and Cyanogenmod 11 for giving the option between Capacitive and Software buttons with their OnePlus One―even though the capacitive buttons had an outdated menu button rather than an overview/recents button.

Thank you for reading, and as always, I will see you in the next post.


Originally published at johnnythai.blogspot.com on June 23, 2015.

Creative Idea: Product, UI,Graphic Design

What is your design idea? UI Design, Graphic Design, Web Design etc are all welcome. This collection is managed by @tkwyoung and @aptnumber2.

Johnny Thai

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Creative Idea: Product, UI,Graphic Design

What is your design idea? UI Design, Graphic Design, Web Design etc are all welcome. This collection is managed by @tkwyoung and @aptnumber2.

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